Abstract
Methods and devices for processing of RF signals according to different gain modes are presented. According to one aspect, an active amplification mode is provided by switchable active paths coupled to respective input RF signals and a passive attenuation mode is provided by switchable passive paths coupled to the respective RF signals. According to another aspect, a common switchable feedback path coupled to the switchable active paths is used to provide an active attenuation mode. Coupling of the common switchable feedback path to the switchable active path is provided by switches of the switchable passive paths, including for coupling both ends of the common switchable feedback path or just one end.
Claims
1. A multi-input multi-gain radio frequency (RF) processing circuit, comprising: a plurality of switchable active paths, each switchable active path of the plurality of switchable active paths coupled between a respective input RF node and an output RF node of the multi-input multi-gain RF processing circuit; a plurality of switchable passive paths associated to the plurality of switchable active paths, each switchable passive path of the plurality of switchable passive paths coupled between the respective input RF node and the output RF node; and a switchable feedback path, wherein the each switchable active path comprises: an amplifier comprising an amplifier input coupled to the respective input RF node, and an amplifier output coupled to a first common node that is common to the plurality of switchable active paths, and the each switchable passive path comprises: an input switch comprising an input terminal coupled to the respective input RF node, and an output terminal coupled to a second common node that is common to the plurality of switchable passive paths and to the switchable feedback path.
2. The multi-input multi-gain radio frequency (RF) processing circuit of claim 1, wherein: the plurality of switchable active paths comprises a first common switchable path segment coupled between the first common node and the output RF node, the first common switchable path segment comprising a common output switch of the plurality of switchable active paths that is coupled to the output RF node.
3. The multi-input multi-gain radio frequency (RF) processing circuit of claim 2, wherein: the first common switchable path segment further comprises at least one attenuator arranged between the first common node and the common output switch of the plurality of switchable active paths.
4. The multi-input multi-gain radio frequency (RF) processing circuit of claim 2, wherein: the first common switchable path segment further comprises an impedance match circuit coupled between the first common node and the at least one attenuator.
5. The multi-input multi-gain radio frequency (RF) processing circuit of claim 2, wherein: the common output switch of the plurality of switchable active paths is a single-pole single-throw switch.
6. The multi-input multi-gain radio frequency (RF) processing circuit of claim 2, wherein: the plurality of switchable passive paths comprises a second common switchable path segment coupled between the second common node and the output RF node, the second common switchable path segment comprising a common output switch of the plurality of switchable passive paths that is coupled to the output RF node.
7. The multi-input multi-gain radio frequency (RF) processing circuit of claim 6, wherein: the second common switchable path segment further comprises at least one attenuator arranged between the second common node and the common output switch of the plurality of switchable passive paths.
8. The multi-input multi-gain radio frequency (RF) processing circuit of claim 6, wherein: the common output switch of the plurality of switchable passive paths is a single-pole single-throw switch.
9. The multi-input multi-gain radio frequency (RF) processing circuit of claim 6, wherein: the switchable feedback path is coupled between the second common node and a node that couples the at least one attenuator to the common output switch of the plurality of switchable passive paths.
10. The multi-input multi-gain radio frequency (RF) processing circuit of claim 9, wherein: the switchable feedback path comprises a switch, a resistor and a capacitor in series connection.
11. The multi-input multi-gain radio frequency (RF) processing circuit of claim 9, wherein: a) operation according to an active amplification mode of the multi-input multi-gain RF processing circuit comprises: activating an amplifier of a switchable active path of the plurality of switchable active paths for amplification of an RF signal coupled to the respective input RF node; closing the common output switch of the plurality of switchable active paths; opening the input switch of the each switchable passive path; and opening the common output switch of the plurality of switchable passive paths, b) operation according to an active attenuation mode of the multi-input multi-gain RF processing circuit comprises: activating an amplifier of a switchable active path of the plurality of switchable active paths for amplification of an RF signal coupled to the respective input RF node; closing the common output switch of the plurality of switchable active paths; closing the input switch of the switchable passive path coupled to the respective input RF node; closing a switch of the switchable feedback path; and closing the common output switch of the plurality of switchable passive paths, and c) operation according to a passive attenuation mode of the multi-input multi-gain RF processing circuit comprises: closing an input switch of a switchable passive path of the plurality of switchable passive paths for attenuation of an RF signal coupled to the respective input RF node; closing the common output switch of the plurality of switchable passive paths; deactivating the amplifier of the each switchable active path of the plurality of switchable active paths; and opening the common output switch of the plurality of switchable active paths.
12. The multi-input multi-gain radio frequency (RF) processing circuit of claim 6, wherein: the switchable feedback path is coupled between the second common node and the first common node.
13. The multi-input multi-gain radio frequency (RF) processing circuit of claim 12, wherein: the switchable feedback path comprises a switch, a resistor and a capacitor in series connection.
14. The multi-input multi-gain radio frequency (RF) processing circuit of claim 12, wherein: a) operation according to an active amplification mode of the multi-input multi-gain RF processing circuit comprises: activating an amplifier of a switchable active path of the plurality of switchable active paths for amplification of an RF signal coupled to the respective input RF node; closing the common output switch of the plurality of switchable active paths; opening the input switch of the each switchable passive path; and opening the common output switch of the plurality of switchable passive paths, b) operation according to an active attenuation mode of the multi-input multi-gain RF processing circuit comprises: activating an amplifier of a switchable active path of the plurality of switchable active paths for amplification of an RF signal coupled to the respective input RF node; closing the common output switch of the plurality of switchable active paths; closing the input switch of the switchable passive path coupled to the respective input RF node; closing a switch of the switchable feedback path; and opening the common output switch of the plurality of switchable passive paths, and c) operation according to a passive attenuation mode of the multi-input multi-gain RF processing circuit comprises: closing an input switch of a switchable passive path of the plurality of switchable passive paths for attenuation of an RF signal coupled to the respective input RF node; closing the common output switch of the plurality of switchable passive paths; opening the switch of the switchable feedback path; deactivating the amplifier of the each switchable active path of the plurality of switchable active paths; and opening the common output switch of the plurality of switchable active paths.
15. The multi-input multi-gain radio frequency (RF) processing circuit of claim 1, wherein: the amplifier of the each switchable active path is a low noise amplifier (LNA).
16. The multi-input multi-gain radio frequency (RF) processing circuit of claim 15, wherein: the LNA comprises metal-oxide-semiconductor (MOS) field effect transistors (FETs), or complementary metal-oxide-semiconductor (CMOS) field effect transistors (FETs).
17. The multi-input multi-gain radio frequency (RF) processing circuit of claim 16, wherein: said transistors are fabricated using one of: a) silicon-on-insulator (SOI) technology, and b) silicon-on-sapphire technology (SOS).
18. An electronic module comprising the multi-input multi-gain radio frequency (RF) processing circuit of claim 1.
19. A method, comprising using the electronic module of claim 18 in one or more electronic systems comprising: a) a television, b) a cellular telephone, c) a personal computer, d) a workstation, e) a radio, f) a video player, g) an audio player, h) a vehicle, i) a medical device, and j) other electronic systems.
20. A multi-input multi-gain radio frequency (RF) processing circuit, comprising: a plurality of switchable active paths comprising respective one or more switches, each switchable active path of the plurality of switchable active paths coupled between a respective input RF node of a plurality of input RF nodes and an output RF node of the multi-input multi-gain RF processing circuit; a plurality of switchable passive paths comprising respective one or more switches, each switchable passive path of the plurality of switchable passive paths coupled between a respective input RF node of the plurality of input RF nodes and the output RF node; and a switchable feedback path, wherein during a passive attenuation mode of operation of the multi-input multi-gain RF processing circuit, the respective one or more switches of a switchable active path of the plurality of switchable active paths are configured to provide a conduction path of an RF signal coupled to the respective input RF node to the output RF node through said switchable active path, the conduction path comprising an amplifier, and the respective one or more switches of a switchable passive path of the plurality of switchable passive paths are configured to couple the switchable feedback path to said conduction path to provide a feedback conduction path between an output and an input of the amplifier.
21. The multi-input multi-gain radio frequency (RF) processing circuit of claim 20, wherein: during an active amplification mode of operation of the multi-input multi-gain RF processing circuit, the respective one or more switches of the switchable active path are configured to provide the conduction path of the RF signal through said switchable active path, and the respective one or more switches of the plurality of switchable passive paths are configured to decouple the RF signal from respective conduction paths of the plurality of switchable passive paths, and during a passive attenuation mode of operation of the multi-input multi-gain RF processing circuit, the respective one or more switches of the switchable passive path are configured to provide a conduction path of the RF signal through said switchable passive path, the conduction path comprising an attenuator, and the respective one or more switches of the plurality of switchable active paths and deactivated states of respective amplifiers of the plurality of switchable active paths are configured to decouple the RF signal from respective conduction paths of the plurality of switchable active paths.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more embodiments of the present disclosure and, together with the description of example embodiments, serve to explain the principles and implementations of the disclosure.
(2) FIG. 1 shows a simplified schematic of another multi-input and multi-gain RF processing circuit comprising a switchable active path that is separate from a switchable passive path.
(3) FIG. 2 shows a simplified schematic of a multi-input and multi-gain RF processing circuit comprising a switchable active path and a switchable passive path.
(4) FIG. 3A shows a simplified schematic of a multi-input and multi-gain RF processing circuit according to an embodiment of the present disclosure comprising dedicated switchable active paths that may be selectively coupled to respective switchable feedback paths, and dedicated switchable passive paths.
(5) FIG. 3B shows processing of an input RF signal through a dedicated switchable active path of the configuration shown in FIG. 3A.
(6) FIG. 3C shows processing of an input RF signal through a dedicated switchable active path that is coupled to a respective switchable feedback path of the configuration shown in FIG. 3A.
(7) FIG. 3D shows processing of an input RF signal through the switchable passive path of the configuration shown in FIG. 3A.
(8) FIG. 4A shows a simplified schematic of a multi-input and multi-gain RF processing circuit according to an embodiment of the present disclosure comprising dedicated switchable active paths that may be selectively coupled to a common switchable feedback path, and dedicated switchable passive paths.
(9) FIG. 4B shows processing of an input RF signal through a dedicated switchable active path of the configuration shown in FIG. 4A.
(10) FIG. 4C shows processing of an input RF signal through a dedicated switchable passive path that is coupled to the switchable feedback path of the configuration shown in FIG. 4A.
(11) FIG. 4D shows processing of an input RF signal through the switchable passive path of the configuration shown in FIG. 4A.
(12) FIG. 5A shows a simplified schematic of a multi-input and multi-gain RF processing circuit according to another embodiment of the present disclosure comprising dedicated switchable active paths that may be selectively coupled to a switchable feedback path, and a switchable passive path.
(13) FIG. 5B shows processing of an input RF signal through a dedicated switchable active path of the configuration shown in FIG. 5A.
(14) FIG. 5C shows processing of an input RF signal through a dedicated switchable passive path that is coupled to the switchable feedback path of the configuration shown in FIG. 5A.
(15) FIG. 5D shows processing of an input RF signal through the switchable passive path of the configuration shown in FIG. 5A.
(16) FIG. 6 is a process chart showing various steps of a method according to the present disclosure for processing a plurality of input RF signals according to multiple gain modes.
(17) Like reference numbers and designations in the various drawings indicate like elements.
DETAILED DESCRIPTION
(18) As used herein, the expressions “a switchable RF processing path”, “a switchable RF path”, or simply “a switchable path”, are synonymous and may refer to an RF signal conduction path that may include active and/or passive elements and at least one switch that is configured to selectively couple/decouple the conduction path to/from a node of a circuit used to receive, process, or output, an RF signal.
(19) As used herein, the expression “a switchable active path” may refer to a switchable path that includes at least on active device, such as, for example, an amplifier or a transistor.
(20) As used herein, the expression “a switchable passive path” may refer to a switchable path that is devoid of any active device.
(21) As used herein, the expression “active amplification” may refer to any processing of an RF signal via an active path, including a switchable active path, to obtain a processed RF signal with a gain that is positive (gain≥0 dB).
(22) As used herein, the expression “active attenuation” may refer to any processing of an RF signal via an active path, including a switchable active path, to obtain a processed RF signal with a gain that is negative (gain≤0 dB).
(23) As used herein, the expression “passive attenuation” may refer to any processing of an RF signal via a passive path, including a switchable passive path, to obtain a processed RF signal with a gain that is negative (gain≤0 dB).
(24) FIG. 2 shows a simplified schematic of a multi-input and multi-gain RF processing circuit (200) comprising a switchable active path (L.sub.SER, 110, 121, 122, SW.sub.OA) and a switchable passive path (131, 132, SW.sub.AP, 141, SW.sub.OP). A person skilled in the art will clearly identify similarities and differences of such configuration (200) with respect to the configuration (100) described above with reference to FIG. 1. In particular, the switchable passive path (131, 132, SW.sub.AP, 141, SW.sub.OP) includes a first switchable path segment (131, 132, SW.sub.AP) that may be selectively coupled via the switch SW.sub.AP to either the switchable active path (L.sub.SER, 110, 121, 122, SW.sub.OA) or to a second switchable path segment (141, SW.sub.OP) of the switchable passive path (131, 132, SW.sub.AP, 141, SW.sub.OP).
(25) With continued reference to FIG. 2, during a passive attenuation mode (gain≤0 dB), the switchable passive path (131, 132, SW.sub.AP, 141, SW.sub.OP) is enabled/activated by configuring the switch SW.sub.AP to couple the first switchable path segment (131, 132, SW.sub.IP) to the second switchable path segment (141, SW.sub.OP). Accordingly, a selected RF signal, RF.sub.S2, of the plurality of input RF signals (e.g., RF.sub.IN1, RF.sub.IN2, RF.sub.IN3, etc.) via the input switch MSW.sub.IN may be processed/attenuated by the two attenuators (131, 132) of the first switchable path segment (131, 132, SW.sub.AP) and by the attenuator (141) of the second switchable path segment (141, SW.sub.OP), and output as the RF.sub.OUT signal through the switch SW.sub.OP.
(26) The configuration (200) of FIG. 2 includes an active attenuation mode provided by coupling of the first switchable path segment (131, 132, SW.sub.AP) to the switchable active path (L.sub.SER, 110, 121, 122, SW.sub.OA). Accordingly, a selected RF signal, RF.sub.S2, of the plurality of input RF signals (e.g., RF.sub.IN1, RF.sub.IN2, RF.sub.IN3, etc.) via the input switch MSW.sub.IN may be processed/attenuated by the two attenuators (131, 132) of the first switchable path segment (131, 132, SW.sub.AP) and further processed/attenuated through the elements (110, 121, 122) of the switchable active path. Differently from the configuration (100) of FIG. 1, the configuration (200) allows for attenuation (e.g., via 131, 132) prior to amplification (e.g., via 110), and therefore for a reduced attenuation post amplification when compared to the configuration (100). Accordingly, for a same attenuation mode (e.g., gain setting, level of attenuation), the configuration (200) of FIG. 2 may provide an improved linearity/distortion performance when compared to the configuration (100) of FIG. 1.
(27) With continued reference to FIG. 2, RF signal amplification may be provided through the switchable active path (L.sub.SER, 110, 121, 122, SW.sub.OA). Operation during such (active) amplification mode is similar to one described above with reference to FIG. 1. In other words, a selected RF signal, RF.sub.S1, of the plurality of input RF signals (e.g., RF.sub.IN1, RF.sub.IN2, RF.sub.IN3, etc.) via the input switch MSW.sub.IN may be processed/amplified via elements (110, 121, 122), and output as the RF.sub.OUT signal through the switch SW.sub.OA.
(28) Similar to the configuration (100) of FIG. 1, the configuration (200) of FIG. 2 includes two switches MSW.sub.IN and SW.sub.AP coupled to the input of the amplifier (110). However, such switches are complex switches (e.g., multi-pole multi-throw MPMT) which may include added parasitic capacitance when compared to the simpler switches SW.sub.IN and SW.sub.IP of FIG. 1 (e.g., single-pole single-throw). For example, as shown in the detail A of FIG. 2, the switch MSW.sub.IN may be equivalent to two switches SW.sub.IN of FIG. 1 having respective throws coupled to the input RF signals (e.g., RF.sub.IN1, RF.sub.IN2, RF.sub.IN3, etc.) for provision of selected RF signals RF.sub.S1 and RF.sub.S2 at respective poles of the two switches. Such added parasitic capacitance coupled to the input of the amplifier (110) may in turn adversely affect noise figure.
(29) Although the configuration (200) of FIG. 2 may provide an improved linearity/distortion performance during the active attenuation mode when compared to the configuration (100) of FIG. 1, such improved performance is obtained at a cost of a degraded noise figure performance due to the added capacitive loading of the (complex) switches.
(30) FIG. 3A shows a simplified schematic of a multi-input and multi-gain RF processing circuit (300A) which is devoid of an input switch (e.g., SW.sub.IN of FIG. 1, MSW.sub.IN of FIG. 2) for selecting of an input RF signal of the plurality of RF signals (e.g., RF.sub.IN1, RF.sub.IN2, RF.sub.IN3, etc.). Instead, the configuration (300A) includes redundant elements that are dedicated for processing of respective input RF signals. Such redundant elements include, for example, a) switches (SW.sub.IP1, SW.sub.IP2, SW.sub.IP3) for provision of respective switchable passive paths (SW.sub.IPn, 141, SW.sub.OP), for n=1, 2, 3, etc.; b) amplifiers (111, 112, 113) for provision of respective switchable active paths (11n, 121, 122, SW.sub.OA) for n=1, 2, 3, etc.; and c) switches (SW.sub.FB1, SW.sub.FB2, SW.sub.FB3) for provision of respective switchable (passive) feedback paths (SW.sub.FBn, R.sub.FBn, C.sub.FBn), for n=1, 2, 3, etc., such switchable feedback paths selectively coupled to respective amplifiers (e.g., 111, 112, 113) for control of gain, including for active amplification mode (i.e., gain≥0 dB) and active attenuation mode (i.e., gain≤0 dB). Further redundancy may include series connected inductors (e.g., L.sub.SER1, L.sub.SER2, L.sub.SER3, etc.) dedicated to each input RF signal (e.g., RF.sub.IN1, RF.sub.IN2, RF.sub.IN3, etc.)
(31) With continued reference to FIG. 3A, the configuration (300A) may allow active attenuation mode via a switchable feedback path (SW.sub.FBn, R.sub.FBn, C.sub.FBn) coupled between input and output of a respective amplifier (11n, n=1, 2, 3, etc.). As known to a person skilled in the art, such feedback may allow reducing a gain of an amplifier via selection of the resistance R.sub.FBn, while the capacitance C.sub.FBn may be used to decouple DC components between input and output of the amplifier. Accordingly, the active attenuation mode (with feedback) provided by the configuration (300A) may include a reduced number of attenuators when compared to the configuration (100) of FIG. 1. Furthermore, in contrast to the configuration (200) of FIG. 2, the active attenuation mode of the configuration (300A) may be provided without any attenuator at the input side of (prior to) the amplifier (e.g., 111, 112, 113). Finally, capacitive loading due to the (simple SPST) switches (e.g., SW.sub.FBn, SW.sub.IPn, n=1, 2, 3, etc.) at the input of the amplifier (e.g., 11n, n=1, 2, 3, etc.) may be reduced compared to the configuration (200) of FIG. 2 (e.g., that includes complex MPMT switch MSW.sub.IN) as well as the configuration (100) of FIG. 1 (e.g., that includes a complex single-pole multi-throw SPMT switch SW.sub.IN).
(32) With further reference to FIG. 3A, it should be noted that the configuration (300A) may not be limited to any number of input RF signals (e.g., RF.sub.IN1, RF.sub.IN2, RF.sub.IN3, etc.), and therefore can be implemented for a single input configuration (n=1) or a configuration having any number of inputs (n=N, with N>1).
(33) As shown in FIG. 3A, the amplifiers (11n, n=1, 2, 3, etc.) of the switchable active paths (11n, 121, 122, SW.sub.OA, n=1, 2, 3, etc.) include outputs that are coupled to a common node, N.sub.CA. Furthermore, the switchable (passive) feedback paths (SW.sub.FBn, R.sub.FBn, C.sub.FBn, n=1, 2, 3, etc.) are coupled at one end to the common node, N.sub.CA, and at the other end to respective inputs of the amplifiers (11n, n=1, 2, 3, etc.), thereby providing respective (output to input) feedbacks to each of the amplifiers. Accordingly, the switchable active paths (11n, 121, 122, SW.sub.OA, n=1, 2, 3, etc.) include a common switchable path segment (121, 122, SW.sub.OA) coupled between the common node, N.sub.CA, and the output node (e.g., RF.sub.OUT). In other words, RF processing through the switchable active paths (11n, 121, 122, SW.sub.OA, n=1, 2, 3, etc.) include conduction through a common path defined by the elements (121, 122, SW.sub.OA).
(34) With continued reference to FIG. 3A, (input) switches (SW.sub.IPn, n=1, 2, 3, etc.) selectively couple (and decouple) respective input RF signals (RF.sub.INn, n=1, 2, 3, etc.) to a common switchable path segment (141, SW.sub.OP) of the switchable passive paths (SW.sub.IPn, 141, SW.sub.OP, n=1, 2, 3, etc.). In other words, each of the switches (SW.sub.IPn, n=1, 2, 3, etc.) is coupled between a respective input RF signals (RF.sub.INn, n=1, 2, 3, etc.) and a common node, N.sub.CP. It follows that the common switchable path segment (141, SW.sub.OP) is coupled between the common node, N.sub.CP, of the switchable passive paths (SW.sub.IPn, 141, SW.sub.OP, n=1, 2, 3, etc.) and the output node (e.g., RF.sub.OUT), and RF processing through the switchable passive paths (SW.sub.IPn, 141, SW.sub.OP, n=1, 2, 3, etc.) includes conduction through a common (conduction) path defined by the elements (141, SW.sub.OA).
(35) Activation of an active amplification mode for a selected input RF signal, RF.sub.INk, k=1, 2, 3, etc., of the configuration (300A) may include: enabling/activating of the amplifier (11k); disabling of all other amplifiers (11n, n≠k); enabling (i.e., turning ON, closing) of the switch SW.sub.OA; disabling (i.e., turning OFF, opening) of the switch SW.sub.OP; and turning OFF of all other switches (SW.sub.FBn, SW.sub.IPn, n=1, 2, 3, etc.). Activation of an active attenuation mode for the selected input RF signal, RF.sub.INk, of the configuration (300A) may include all of the steps described above for activation of the active amplification mode, at the exception of the switch SW.sub.FBk that should be turned ON in order to enable feedback for the amplifier (11k). Activation of a passive attenuation mode for the selected input RF signal, RF.sub.INk, of the configuration (300A) may include: enabling (i.e., turning ON, closing) of the switches SW.sub.IPk and SW.sub.OP; disabling/deactivating of all of the amplifiers (11n, n=1, 2, 3, etc.); and disabling of all other switches (SW.sub.FBn, n=1, 2, 3, etc.), (SW.sub.IPn, n≠k) and SW.sub.OA.
(36) FIG. 3B shows a configuration (300B) of the multi-input multi-gain RF processing circuit of FIG. 3A for processing of an input RF signal, RF.sub.IN1, through a dedicated switchable active path (Ilk, 121, 122, SW.sub.OA, k=1). In other words, the configuration (300B) shows a processing path of a selected RF signal, RF.sub.INk, k=1, for the active amplification mode. As described above, provision of such configuration includes enabling/activating of the amplifier (111); disabling of all other amplifiers (e.g., 112, 113); enabling (i.e., turning ON, closing) of the switch SW.sub.OA; disabling (i.e., turning OFF, opening) of the switch SW.sub.OP; and turning OFF of all other switches (SW.sub.FBn, SW.sub.IPn, n=1, 2, 3, etc.).
(37) FIG. 3C shows a configuration (300C) of the multi-input multi-gain RF processing circuit of FIG. 3A for processing of an input RF signal, RF.sub.IN1, through a dedicated switchable active path (11k, 121, 122, SW.sub.OA, k=1) coupled to a respective switchable feedback path (SW.sub.FB1, R.sub.FB1, C.sub.FB1). In other words, the configuration (300C) shows a processing path of a selected RF signal, RF.sub.INk, k=1, for the active attenuation mode. As described above, provision of such configuration includes enabling/activating of the amplifier (111); disabling of all other amplifiers (e.g., 112, 113); enabling (i.e., turning ON, closing) of the switch SW.sub.OA; disabling (i.e., turning OFF, opening) of the switch SW.sub.OP; turning ON of the switch SW.sub.FB1; and turning OFF of switches (SW.sub.FB2, SW.sub.FB3) and (SW.sub.IPn, n=1, 2, 3, etc.).
(38) FIG. 3D shows a configuration (300D) of the multi-input multi-gain RF processing circuit of FIG. 3A for processing of an input RF signal, RF.sub.IN1, through a dedicated switchable passive path (SW.sub.IPk, 141, SW.sub.OP, k=1). In other words, the configuration (300D) shows a processing path of a selected RF signal, RF.sub.INk, k=1, for the passive amplification mode. As described above, provision of such configuration includes enabling of the switches SW.sub.IP1 and SW.sub.OP; disabling/deactivating of all of the amplifiers (11n, n=1, 2, 3, etc.); and disabling of all other switches (SW.sub.FBn, n=1, 2, 3, etc.), (SW.sub.IP2, SW.sub.IP3) and SW.sub.OA.
(39) FIG. 4A shows a simplified schematic of a multi-input and multi-gain RF processing circuit (400A) according to an embodiment of the present disclosure comprising dedicated switchable active paths (11n, 121, 122, SW.sub.OA, n=1, 2, 3, etc.) that may be selectively coupled to a common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB), and dedicated switchable passive paths (SW.sub.IPn, 141, SW.sub.OP, n=1, 2, 3, etc.). In particular, the configuration (400A) of FIG. 4A is based on the configuration (300A) of FIG. 3A wherein elements of the switchable passive paths (SW.sub.IPn, 141, SW.sub.OP, n=1, 2, 3, etc.) are reused for selective coupling of the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB) to the switchable active paths (11n, 121, 122, SW.sub.OA, n=1, 2, 3, etc.). This includes reuse of the input switches (SW.sub.IPn, n=1, 2, 3, etc.) and the output switch SW.sub.OP of the switchable passive paths (SW.sub.IPn, 141, SW.sub.OP, n=1, 2, 3, etc.).
(40) The configuration (400A) of FIG. 4A may provide all of the benefits of the configuration (300A) described above with reference to FIG. 3A, with added benefits provided by a reduction of (parasitic) capacitive loading to inputs of the amplifiers (11n, n=1, 2, 3, etc.) due to a lesser number of switches (i.e., removal of all but one of the switches SW.sub.FBn, n=1, 2, 3, etc.) coupled to such inputs, as well as a reduction in number of elements, and therefore cost and physical area, of the circuit.
(41) With further reference to FIG. 4A, during an active amplification mode, one of the amplifiers (11n, n=1, 2, 3, etc.) may be activated (e.g., turned ON, enabled) while the other amplifiers are deactivated, and the switch SW.sub.OA may be turned ON to couple the amplified RF signal to the output node (e.g., RF.sub.OUT). Furthermore, switches (SW.sub.IPn, n=1, 2, 3, etc.) and SW.sub.OP may be turn OFF to avoid conduction through the attenuator (141) and the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB). An exemplary processing path (400B) of the input RF signal, RF.sub.N1, for the active amplification mode provided by the configuration (400A) of FIG. 4A is shown in FIG. 4B.
(42) Active attenuation mode of the configuration (400A) shown in FIG. 4A may be provided by further coupling of the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB) to a conduction path provided by the active amplification mode (e.g., conduction path shown in FIG. 4B). This includes closing of a corresponding (input) switch (SW.sub.IPn, n=1, 2, 3, etc.) to couple one end of the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB) that is coupled to the common node, N.sub.CP, to an input of an activated amplifier (11n, n=1, 2, 3, etc.), and closing of the switch SW.sub.OP to couple the output node (e.g., RF.sub.OUT) to the other end of the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB). According to one embodiment of the present disclosure, a provided feedback path may be limited to conduction through elements (C.sub.FB, R.sub.FB) by configuring the attenuator (141) for isolation mode (e.g., high series impedance) while turning ON the switch SW.sub.FB. According to another embodiment of the present disclosure, a provided feedback path may further include conduction through the attenuator (141) by configuring such attenuator for an impedance appropriate for conduction (e.g., different from high series impedance) while switch SW.sub.FB remains ON. An exemplary processing path (400C) of the input RF signal, RF.sub.N1, for the active attenuation mode provided by the configuration (400A) of FIG. 4A is shown in FIG. 4C. In FIG. 4C, a conduction path of the RF signal for further attenuation/feedback control through the attenuator (141) is shown with a different dashed/dotted line.
(43) With further reference to FIG. 4A, during a passive attenuation mode, one of the switches (SW.sub.IPn, n=1, 2, 3, etc.) may be turned ON to selectively couple an input RF signal (e.g., RF.sub.INk, k=1, 2, 3, etc.) for processing through the attenuator (141) that is coupled between the common node, N.sub.CP and the switch SW.sub.OP, and the switch SW.sub.OP may be turned ON to selectively couple the attenuated RF signal to the output node (e.g., RF.sub.OUT). Furthermore, in order to avoid conduction through the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB), the switch SW.sub.FB, may be turned OFF during the passive attenuation mode. In some embodiment of the present disclosure, the switch SW.sub.FB, may be turned ON in order to provide further control of the attenuation during the passive attenuation mode. Such further control of the attenuation is based on conduction through parallel conduction paths/segments provided by the attenuator (141) and the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB). Amplifiers (11n, n=1, 2, 3, etc.) may be deactivated and the switch SW.sub.OA may be turned OFF during the passive attenuation mode. An exemplary processing path (400D) of the input RF signal, RF.sub.N1, for the passive attenuation mode provided by the configuration (400A) of FIG. 4A is shown in FIG. 4D. In FIG. 4D, a conduction path of the RF signal for further attenuation control through the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB) is shown with a different dashed/dotted line.
(44) In the configuration (400A) of FIG. 4A, element (450) refers to a match circuit that is configured to provide impedance matching between the output of the amplifier (e.g., 11n, n=1, 2, 3, etc.) and the attenuator (121). As known to a person skilled in the art, the various elements of the multi-input and multi-gain RF processing circuit (400A) of FIG. 4A, including attenuators (121, 122) and inductors (L.sub.SERn, n=1, 2, 3, etc.) may be designed in view of a desired characteristic impedance of the circuit (at a frequency of operation of the circuit), traditionally of a (nonlimiting) value that is equal to 50 Ohms. This means that impedance seen at the input (e.g., nodes carrying RF.sub.INn, n=1, 2, 3, etc.) and output nodes (e.g., node carrying RF.sub.OUT) of the circuit (400A) may be equal to 50 Ohms. Accordingly, during the active attenuation mode feedback is provided by coupling the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB) to the relatively low impedance output node (e.g., RF.sub.OUT at 50 Ohms) as shown in FIG. 4A. However, coupling to a higher impedance node may provide some advantages, including for example, higher voltage swings and thus higher feedback resistor values (e.g., R.sub.FB) in the feedback path for a larger open loop gain which is advantageous in a feedback system. Furthermore, as known to a person skilled in the art, an output impedance of the amplifier (e.g., 11n, n=1, 2, 3, etc.) may be a function of a size of transistors used in the amplifier which in turn may be a function of a power (e.g., bias current) of the amplifier. Accordingly, a low noise amplifier (LNA) that is configured to operate at low power may have an output impedance that is substantially higher than a power amplifier (PA) that is configured to operate at substantially higher power. For example, the output impedance of an LNA may be substantially higher than 50 Ohms, and the output impedance of a PA may be substantially lower than 50 Ohms. Teachings according to the present disclosure take advantage of the output impedance of the amplifier (e.g., 11n, n=1, 2, 3, etc.) to provide a feedback path coupled to a higher impedance node. This is shown in the embodiment represented by FIG. 5A.
(45) FIG. 5A shows a simplified schematic of a multi-input and multi-gain RF processing circuit (500A) according to an embodiment of the present disclosure comprising dedicated switchable active paths (11n, 121, 122, SW.sub.OA, n=1, 2, 3, etc.) that may be selectively coupled to a common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB), and dedicated switchable passive paths (SW.sub.IPn, 141, SW.sub.OP, n=1, 2, 3, etc.). In particular, the configuration (500A) is based on the configuration (400A) wherein the switches (SW.sub.IPn, n=1, 2, 3, etc.) of the switchable passive paths (SW.sub.IPn, 141, SW.sub.OP, n=1, 2, 3, etc.) are reused for selective coupling of one end (coupled to common node N.sub.CP) of the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB) to inputs of respective amplifiers (11n, n=1, 2, 3, etc.) of the switchable active paths (11n, 121, 122, SW.sub.OA, n=1, 2, 3, etc.), while the other end of the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB) is coupled (e.g., connected) to the common node, N.sub.CA. Accordingly, for an exemplary case where the multi-input and multi-gain RF processing circuit (500A) is used in a receive side of an RF frontend module, an impedance at the common node, N.sub.CA, may be provided by an output impedance of the LNA (11n, n=1, 2, 3, etc.), and therefore at a value that may be substantially higher than the impedance at the output node (e.g., RF.sub.OUT). It should be noted that in order to take advantage of the higher output impedance of the LNA, the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB) may be coupled directly to the output of the LNA (11n, n=1, 2, 3, etc.) and before the match circuit (450).
(46) An exemplary processing path (500B) of the input RF signal, RF.sub.N1, for the active amplification mode provided by the configuration (500A) of FIG. 5A is shown in FIG. 5B. In such mode of operation, only one of the amplifiers (e.g., 111) is activated while the other (e.g., 112, 113) are deactivated. Furthermore, as shown in FIG. 5B, the switch SW.sub.OA may be turned ON (i.e., closed) to couple the amplified RF signal trough the amplifier (111) to the output node (e.g., RF.sub.OUT). As described above with reference to other figures, the attenuators (e.g., 121, 122) may be configured to provide a desired level of amplification through the processing path (e.g., 111, 450, 121, 122). All other switches, including (SW.sub.IPn, n=1, 2, 3, etc.), SW.sub.FB and SW.sub.OP may be turned OFF as shown in FIG. 5B.
(47) An exemplary processing path (500C) of the input RF signal, RF.sub.N1, for the active attenuation mode provided by the configuration (500A) of FIG. 5A is shown in FIG. 5C. Such mode of operation may be provided by coupling of the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB) to a conduction path provided by the active amplification mode (e.g., conduction path shown in FIG. 5B). This includes closing of a corresponding (input) switch (e.g., SW.sub.IP1 as shown in FIG. 1C) to couple one end of the common switchable feedback path (SW.sub.FB, R.sub.FB, C.sub.FB) to an input of an activated amplifier (e.g., 111 as shown in FIG. 5C).
(48) An exemplary processing path (500D) of the input RF signal, RF.sub.N1, for the passive attenuation mode provided by the configuration (500A) of FIG. 5A is shown in FIG. 5D. In such mode of operation, the switch SW.sub.IP1 may be turned ON to couple the input RF signal RF.sub.IN1 for processing through the attenuator (141), and the switch SW.sub.OP may be turned ON to couple the attenuated RF signal to the output node (e.g., RF.sub.OUT). All other switches, including SW.sub.IP2, SW.sub.IP3, SWFS and SW.sub.OA, may be turned OFF as shown in FIG. 5D. Furthermore, amplifiers (112, 113) may be deactivated.
(49) FIG. 6 is a process chart (600) showing various steps of a method according to the present disclosure for processing a plurality of input RF signals according to multiple gain modes. As shown in FIG. 6 such steps comprise: coupling a plurality of switchable active paths between respective input RF nodes of a plurality of input RF nodes and an output RF node, per step (610); coupling a plurality of switchable passive paths between respective input RF nodes of the plurality of input RF nodes and the output RF node, per step (620); coupling an input RF signal of the plurality of input RF signals to an input RF node of the plurality of input RF nodes, per step (630); for operation according to an active amplification mode, configuring a switchable active path of the plurality of switchable active paths that is coupled to the input RF node for conduction of the input RF signal through an amplifier of the switchable active path, thereby obtaining an amplified RF signal at the output RF node, per step (640); for operation according to an active attenuation mode, configuring the switchable active path for conduction of the input RF signal through the amplifier of the switchable active path, and configuring a switchable passive path of the plurality of switchable passive paths that is coupled to the input RF node for coupling of a switchable feedback path between an input and an output of the amplifier of the switchable active path, thereby obtaining an attenuated RF signal at the output RF node, per step (650); and for operation according to a passive attenuation mode, configuring the switchable passive path for conduction of the input RF signal through an attenuator of the switchable passive path, thereby obtaining an attenuated RF signal at the output RF node, per step (660).
(50) The term “MOSFET”, as used in this disclosure, includes any field effect transistor (FET) having an insulated gate whose voltage determines the conductivity of the transistor, and encompasses insulated gates having a metal or metal-like, insulator, and/or semiconductor structure. The terms “metal” or “metal-like” include at least one electrically conductive material (such as aluminum, copper, or other metal, or highly doped polysilicon, graphene, or other electrical conductor), “insulator” includes at least one insulating material (such as silicon oxide or other dielectric material), and “semiconductor” includes at least one semiconductor material.
(51) As used in this disclosure, the term “radio frequency” (RF) refers to a rate of oscillation in the range of about 3 kHz to about 300 GHz. This term also includes the frequencies used in wireless communication systems. An RF frequency may be the frequency of an electromagnetic wave or of an alternating voltage or current in a circuit.
(52) Various embodiments of the invention can be implemented to meet a wide variety of specifications. Unless otherwise noted above, selection of suitable component values is a matter of design choice. Various embodiments of the invention may be implemented in any suitable integrated circuit (IC) technology (including but not limited to MOSFET structures), or in hybrid or discrete circuit forms. Integrated circuit embodiments may be fabricated using any suitable substrates and processes, including but not limited to standard bulk silicon, high-resistivity bulk CMOS, silicon-on-insulator (SOI), and silicon-on-sapphire (SOS). Unless otherwise noted above, embodiments of the invention may be implemented in other transistor technologies such as bipolar, BiCMOS, LDMOS, BCD, GaAs HBT, GaN HEMT, GaAs pHEMT, and MESFET technologies. However, embodiments of the invention are particularly useful when fabricated using an SOI or SOS based process, or when fabricated with processes having similar characteristics. Fabrication in CMOS using SOI or SOS processes enables circuits with low power consumption, the ability to withstand high power signals during operation due to FET stacking, good linearity, and high frequency operation (i.e., radio frequencies up to and exceeding 300 GHz). Monolithic IC implementation is particularly useful since parasitic capacitances generally can be kept low (or at a minimum, kept uniform across all units, permitting them to be compensated) by careful design.
(53) Voltage levels may be adjusted, and/or voltage and/or logic signal polarities reversed, depending on a particular specification and/or implementing technology (e.g., NMOS, PMOS, or CMOS, and enhancement mode or depletion mode transistor devices). Component voltage, current, and power handling capabilities may be adapted as needed, for example, by adjusting device sizes, serially “stacking” components (particularly FETs) to withstand greater voltages, and/or using multiple components in parallel to handle greater currents. Additional circuit components may be added to enhance the capabilities of the disclosed circuits and/or to provide additional functionality without significantly altering the functionality of the disclosed circuits.
(54) Circuits and devices in accordance with the present invention may be used alone or in combination with other components, circuits, and devices. Embodiments of the present invention may be fabricated as integrated circuits (ICs), which may be encased in IC packages and/or in modules for ease of handling, manufacture, and/or improved performance. In particular, IC embodiments of this invention are often used in modules in which one or more of such ICs are combined with other circuit blocks (e.g., filters, amplifiers, passive components, and possibly additional ICs) into one package. The ICs and/or modules are then typically combined with other components, often on a printed circuit board, to form part of an end product such as a cellular telephone, laptop computer, or electronic tablet, or to form a higher-level module which may be used in a wide variety of products, such as vehicles, test equipment, medical devices, etc. Through various configurations of modules and assemblies, such ICs typically enable a mode of communication, often wireless communication.
(55) A number of embodiments of the invention have been described. It is to be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, some of the steps described above may be order independent, and thus can be performed in an order different from that described. Further, some of the steps described above may be optional. Various activities described with respect to the methods identified above can be executed in repetitive, serial, and/or parallel fashion.
(56) It is to be understood that the foregoing description is intended to illustrate and not to limit the scope of the invention, which is defined by the scope of the following claims, and that other embodiments are within the scope of the claims. In particular, the scope of the invention includes any and all feasible combinations of one or more of the processes, machines, manufactures, or compositions of matter set forth in the claims below. (Note that the parenthetical labels for claim elements are for ease of referring to such elements, and do not in themselves indicate a particular required ordering or enumeration of elements; further, such labels may be reused in dependent claims as references to additional elements without being regarded as starting a conflicting labeling sequence).
