Circuits, devices and methods related to amplification with active gain bypass
10951173 ยท 2021-03-16
Assignee
Inventors
Cpc classification
H03F2203/21112
ELECTRICITY
H03F1/0277
ELECTRICITY
H03F2203/21103
ELECTRICITY
H03F2203/21109
ELECTRICITY
H03F2200/249
ELECTRICITY
H03F2200/222
ELECTRICITY
H03F1/56
ELECTRICITY
H03F2203/7236
ELECTRICITY
H03F2203/7215
ELECTRICITY
International classification
H03F1/22
ELECTRICITY
H03F3/72
ELECTRICITY
H03F1/02
ELECTRICITY
Abstract
Circuits, devices and methods related to amplification with active gain bypass. In some embodiments, an amplifier can include a first amplification path implemented to amplify a signal, and having a cascode arrangement of a first input transistor and a cascode transistor to provide a first gain for the signal when in a first mode. The amplifier can further include a second amplification path implemented to provide a second gain for the signal while bypassing at least a portion of the first amplification path when in a second mode. The second amplification path can include a cascode arrangement of a second input transistor and the cascode transistor shared with the first amplification path. The amplifier can further include a switch configured to allow routing of the signal through the first amplification path in the first mode or the second amplification path in the second mode.
Claims
1. A radio-frequency amplifier comprising: a first amplification path implemented to receive and amplify a signal with a first gain, and including a cascode arrangement of a first input transistor and a cascode transistor; a second amplification path implemented to receive and amplify a signal with a second gain, and including a cascode arrangement of a second input transistor and the cascode transistor shared with the first amplification path, the first and second amplification paths having separate input nodes, the signal received by the first amplification path through the respective input node substantially the same as the signal received by the second amplification path through the respective input node; and a control circuit configured to allow operation of the first amplification path when in a first mode and to allow operation of the second amplification path when in a second mode.
2. The radio-frequency amplifier of claim 1 further comprising one or more switches implemented for either or both of the first and second amplification paths, the one or more switches configured to support the operation of the first amplification path when in the first mode and to support the operation of the second amplification path when in the second mode.
3. The radio-frequency amplifier of claim 2 wherein the control circuit is configured to control the one or more switches.
4. The radio-frequency amplifier of claim 3 wherein the control circuit is further configured to control operation of the some or all of the first input transistor, the second input transistor and the cascode transistor.
5. The radio-frequency amplifier of claim 4 wherein the control circuit is configured to disable the second input transistor when in the first mode, and to disable the first input transistor when in the second mode.
6. The radio-frequency amplifier of claim 3 wherein the one or more switches includes a switch implemented along an input path to the second input transistor.
7. The radio-frequency amplifier of claim 6 wherein the switch along the input path to the second input transistor is configured to be open when in the first mode, and to be closed when in the second mode.
8. The radio-frequency amplifier of claim 6 wherein the one or more switches further includes a switch implemented between the first input transistor and the cascode transistor, and a switch implemented between the second input transistor and the cascode transistor.
9. The radio-frequency amplifier of claim 8 wherein the switch between the first input transistor and the cascode transistor is configured to be closed when in the first mode, and to be open when in the second mode, and the switch between the second input transistor and the cascode transistor is configured to be open when in the first mode, and to be closed when in the second mode.
10. The radio-frequency amplifier of claim 6 wherein the second amplification path further includes an attenuator implemented along the input path to the second input transistor.
11. The radio-frequency amplifier of claim 6 wherein the second amplification path further includes a matching network implemented along the input path to the second input transistor.
12. A radio-frequency module comprising: a packaging substrate configured to receive a plurality of components; and an amplifier implemented on the packaging substrate, the amplifier including a first amplification path implemented to receive and amplify a signal with a first gain, and including a cascode arrangement of a first input transistor and a cascode transistor, the amplifier further including a second amplification path implemented to receive and amplify a signal with a second gain, and including a cascode arrangement of a second input transistor and the cascode transistor shared with the first amplification path, the first and second amplification paths having separate input nodes, the signal received by the first amplification path through the respective input node substantially the same as the signal received by the second amplification path through the respective input node, the amplifier further including a control circuit configured to allow operation of the first amplification path when in a first mode and to allow operation of the second amplification path when in a second mode.
13. The radio-frequency module of claim 12 wherein the amplifier is implemented on a semiconductor die that is mounted on the packaging substrate.
14. A wireless device comprising: an antenna; an amplifier in communication with the antenna and including a first amplification path implemented to receive and amplify a signal with a first gain, and including a cascode arrangement of a first input transistor and a cascode transistor, the amplifier further including a second amplification path implemented to receive and amplify a signal with a second gain, and including a cascode arrangement of a second input transistor and the cascode transistor shared with the first amplification path, the first and second amplification paths having separate input nodes, the signal received by the first amplification path through the respective input node substantially the same as the signal received by the second amplification path through the respective input node, the amplifier further including a control circuit configured to allow operation of the first amplification path when in a first mode and to allow operation of the second amplification path when in a second mode; and a transceiver configured to process an amplified signal generated by the amplifier.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION OF SOME EMBODIMENTS
(19) The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the claimed invention.
(20) In many wireless applications, receivers typically require large dynamic ranges, and such a requirement can be achieved through multiple gain states with varying levels of gain, noise figure, and linearity. For example, a smaller signal may require a gain state with a higher gain, a lower noise figure, and a reasonable but not extremely high linearity performance. A higher signal level may require a lower gain, a significantly relaxed noise figure, and a high linearity to amplify the signal with good fidelity. These gain states may also have some requirement to maintain a similar phase shift as changes are made from one gain state to another.
(21) It is noted that in wireless designs, a high gain state with a low noise figure typically cannot tolerate insertion loss placed in series with a low-noise amplifier (LNA). It is also noted that a low gain state with a relaxed noise figure typically requires a series switch and potentially an attenuator to achieve high linearity levels. It is further noted that an LNA can be entirely bypassed; however, phase shift can be difficult to maintain as one switches from an active gain mode to a full passive bypass mode.
(22) Described herein are architectures, circuits, devices and methods related to, among others, a radio-frequency (RF) amplifier having an active gain bypass circuit.
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(24) In some embodiments, an LNA can include a second amplification path configured to selectively divert a signal away from a primary input transistor (e.g., the first transistor M.sub.1 in
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(26) In the example of
(27) In the example of
(28) In some embodiments, the second amplification path 104 can further include a capacitance C.sub.2 and a matching network N.sub.2 (112) in series with the switch S.sub.2. For example, the capacitance C.sub.2 and the matching network N.sub.2 can be implemented in series between the switch S.sub.2 and the attenuator 114. In some embodiments, the matching network N.sub.2 can be configured to provide matching of an input impedance approximately the same as the input impedance for a first-gain operation involving the first amplification path involving the cascode arrangement of M.sub.1 and M.sub.CAS. The matching network N.sub.2 can also be configured to provide a phase shift that is approximately the same as the phase shift associated with the first amplification path.
(29) In some embodiments, the switch S.sub.2 can be configured to provide a low parasitic effect (e.g., low parasitic capacitance). Thus, when S.sub.2 is OFF during operation of the first amplification path (through M.sub.1), S.sub.2 provides a minimal or reduced parasitic impact to such a first amplification path. Accordingly, when the LNA 100 is in the first gain mode (G.sub.0 mode), an optimum or desired combination of gain and noise figure (NF) can be achieved. It is noted that in the first amplification path involving the cascode arrangement of M.sub.1 and M.sub.CAS, the foregoing G.sub.0 mode can be achieved by an absence of losses associated with a series switch (such as S.sub.2 in the second amplification path 104) and a series attenuator (such as the attenuator 114 in the second amplification path 104). In such a configuration, linearity may not be ideal; however, an optimum or desired combination of gain and noise figure can be achieved.
(30) In some embodiments, the foregoing first gain mode (G.sub.0 mode) can be a high gain mode; and such a gain mode can be utilized, for example, when the received signal is relatively weak. As described herein, the second amplification path 104 can be configured (e.g., with a low parasitic switch S.sub.2) so as to allow the first amplification path to achieve such a high gain for the weak signal.
(31) In some embodiments, the LNA 100 of
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(34) Such gain modes can be achieved by operating the first input transistor M.sub.1, the second input transistor M.sub.2, and the switch S.sub.2 as listed in Table 1.
(35) TABLE-US-00001 TABLE 1 Gain mode Gain achieved M1 state M2 state S2 state G0 High ON OFF OFF G2 Low OFF ON ON
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(45) TABLE-US-00002 TABLE 2 Gain Gain Switch Switch mode achieved M1 state M2 state S2 state 160 state 162 state G0 High ON OFF OFF ON OFF G2 Low OFF ON ON OFF ON
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(47) As described in reference to
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(49) In the various examples described herein, LNAs are shown to have amplifying transistors and switches implemented as field-effect transistors (FETs). It will be understood that one or more features of the present disclosure can also be implemented utilizing other types of transistors. For example, amplifying transistors and switches can be implemented as bipolar-junction transistors (BJTs), FETs, or any combination thereof.
(50) In some embodiments, an LNA having one or more features as described herein can utilize a second amplification path (also referred to herein as an active gain bypass circuit) to achieve a second gain mode operation, also as described herein. Such a second gain mode of operation can provide, for example, a second gain (G.sub.2) having a third-order input intercept point (IIP3) that is greater than 10 dBm, with minimal or reduced impact to an optimal gain and noise figure combination of a first (e.g., primary) gain mode (G.sub.0).
(51) In some embodiments, and as described herein, the foregoing active gain bypass circuit can be implemented to allow the LNA to maintain a substantially same phase in both of the first and second gain modes. Such same-phase feature is typically important for, for example, receiver error vector magnitude (EVM) performance.
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(54) In some embodiments, the semiconductor die 100 of
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(59) The DRx module 300 includes a number of paths between the input and the output of the DRx module 300. The DRx module 300 includes a bypass path between the input and the output activated by a bypass switch 519 controlled by the DRx controller 502. Although
(60) The DRx module 300 includes a number of multiplexer paths including a first multiplexer 511 and a second multiplexer 512. The multiplexer paths include a number of on-module paths that include the first multiplexer 511, a bandpass filter 613a-613d implemented on the packaging substrate 501, an amplifier 100a-100d implemented on the packaging substrate 501, and the second multiplexer 512. The multiplexer paths include one or more off-module paths that include the first multiplexer 511, a bandpass filter 513 implemented off the packaging substrate 501, an amplifier 100e, and the second multiplexer 512. The amplifier 514 may be a wide-band amplifier implemented on the packaging substrate 501 or may also be implemented off the packaging substrate 501. In some embodiments, the amplifiers 100a-100d, 100e may be variable-gain amplifiers and/or variable-current amplifiers.
(61) A DRx controller 502 is configured to selectively activate one or more of the plurality of paths between the input and the output. In some implementations, the DRx controller 502 is configured to selectively activate one or more of the plurality of paths based on a band select signal received by the DRx controller 502 (e.g., from a communications controller). The DRx controller 502 may selectively activate the paths by, for example, opening or closing the bypass switch 519, enabling or disabling the amplifiers 100a-100d, 100e, controlling the multiplexers 511, 512, or through other mechanisms. For example, the DRx controller 502 may open or close switches along the paths (e.g., between the filters 613a-613d, 513 and the amplifiers 100a-100d, 100e) or by setting the gain of the amplifiers 100a-100d, 100e to substantially zero.
(62) In the example DRx module 300 of
(63) In some implementations, an architecture, device and/or circuit having one or more features described herein can be included in an RF device such as a wireless device. Such an architecture, device and/or circuit can be implemented directly in the wireless device, in one or more modular forms as described herein, or in some combination thereof. In some embodiments, such a wireless device can include, for example, a cellular phone, a smart-phone, a hand-held wireless device with or without phone functionality, a wireless tablet, a wireless router, a wireless access point, a wireless base station, etc. Although described in the context of wireless devices, it will be understood that one or more features of the present disclosure can also be implemented in other RF systems such as base stations.
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(66) The baseband sub-system 708 is shown to be connected to a user interface 702 to facilitate various input and output of voice and/or data provided to and received from the user. The baseband sub-system 708 can also be connected to a memory 504 that is configured to store data and/or instructions to facilitate the operation of the wireless device, and/or to provide storage of information for the user.
(67) In the example of
(68) In the example of
(69) A number of other wireless device configurations can utilize one or more features described herein. For example, a wireless device does not need to be a multi-band device. In another example, a wireless device can include additional antennas such as diversity antenna, and additional connectivity features such as Wi-Fi, Bluetooth, and GPS.
(70) Unless the context clearly requires otherwise, throughout the description and the claims, the words comprise, comprising, and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of including, but not limited to. The word coupled, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words herein, above, below, and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word or in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.
(71) The above detailed description of embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed above. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. For example, while processes or blocks are presented in a given order, alternative embodiments may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times.
(72) The teachings of the invention provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments.
(73) While some embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.