Devices and methods related to electrostatic discharge-protected CMOS switches
09692120 ยท 2017-06-27
Assignee
Inventors
Cpc classification
H10D89/601
ELECTRICITY
H02H9/046
ELECTRICITY
H01L2223/6677
ELECTRICITY
H02H9/045
ELECTRICITY
H01Q1/50
ELECTRICITY
International classification
H01Q1/52
ELECTRICITY
H01Q1/50
ELECTRICITY
H01L23/498
ELECTRICITY
H01L27/02
ELECTRICITY
H01L27/088
ELECTRICITY
Abstract
Disclosed are devices and methods related to a CMOS switch for radio-frequency (RF) applications. In some embodiments, the switch can be configured to include a resistive body-floating circuit to provide improved power handling capability. The switch can further include an electrostatic discharge (ESD) protection circuit disposed relative to the switch to provide ESD protection for the switch. Such a switch can be implemented for different switching applications in wireless devices such as cell phones, including band-selection switching and transmit/receive switching.
Claims
1. A radio-frequency switching apparatus comprising: a switch implemented in a Complementary Metal-Oxide-Semiconductor technology; an electrostatic discharge protection circuit configured to provide electrostatic discharge protection for the switch; and a controller configured to control the switch, the controller including a bandgap reference, a low dropout voltage regulator, and digital logic.
2. The radio-frequency switching apparatus of claim 1 wherein the controller is integrated with the switch.
3. The radio-frequency switching apparatus of claim 1 wherein the controller is configured to generate a bias voltage for the switch.
4. The radio-frequency switching apparatus of claim 1 wherein the switch includes a transistor connected to an unsilicided poly gate resistor.
5. The radio-frequency switching apparatus of claim 4 wherein the resistance of the unsilicided poly gate resistor is approximately 40 kilo-ohms.
6. The radio-frequency switching apparatus of claim 1 wherein the switch includes a resistive body-floating circuit.
7. The radio-frequency switching apparatus of claim 6 wherein the switch is implemented in a bulk Complementary Metal-Oxide-Semiconductor technology.
8. The radio-frequency switching apparatus of claim 7 wherein a source-to-bulk voltage and a drain-to-bulk voltage are reverse-biased through the resistive body-floating circuit.
9. The radio-frequency switching apparatus of claim 8 wherein, when the radio-frequency switching apparatus is in an off state, the source-to-bulk voltage and the drain-to-bulk voltage are reversed-biased at a voltage level between a gate-to-drain voltage level applied when the switch is on and a voltage level corresponding to a gate oxide breakdown voltage.
10. The radio-frequency switching apparatus of claim 9 wherein the source-to-bulk voltage and the drain-to-bulk voltage are approximately 1 volt.
11. A radio-frequency module comprising: a packaging substrate; and a radio-frequency switching apparatus mounted on the packaging substrate, the radio-frequency switching apparatus including a switch, an electrostatic discharge protection circuit and a controller, the switch implemented in a Complementary Metal-Oxide-Semiconductor technology, the electrostatic discharge protection circuit configured to provide electrostatic discharge protection for the switch, and the controller configured to control the switch, the controller including a bandgap reference, a low dropout voltage regulator, and digital logic.
12. The radio-frequency module of claim 11 wherein the radio-frequency module is a part of a multi-chip-module.
13. The radio-frequency module of claim 12 wherein the multi-chip-module is a laminated multi-chip-module.
14. The radio-frequency module of claim 13 wherein the laminated multi-chip-module includes a laminate substrate with land grid array type perimeter pads.
15. The radio-frequency module of claim 11 wherein the electrostatic discharge protection circuit includes one or more diodes.
16. The radio-frequency module of claim 11 wherein the electrostatic discharge protection circuit is electrically connected to a port of the switch.
17. The radio-frequency module of claim 16 wherein the port is an antenna port of the switch.
18. A wireless device comprising: an antenna configured to facilitate transmission and reception of radio-frequency signals; and a radio-frequency module in communication with the antenna, the radio-frequency module including a switch implemented in a Complementary Metal-Oxide-Semiconductor technology, an electrostatic discharge protection circuit configured to provide electrostatic discharge protection for the switch, and a controller configured to control the switch, the controller including a bandgap reference, a low dropout voltage regulator, and digital logic.
19. The wireless device of claim 18 wherein the electrostatic discharge protection circuit is implemented at an antenna port of the switch.
20. The wireless device of claim 18 wherein the electrostatic discharge protection circuit includes one or more diodes.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION OF SOME EMBODIMENTS
(14) The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the claimed invention.
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(16) In some embodiments, the switching apparatus 100 of
(17) Disclosed herein are example configurations of a switching apparatus that can provide advantageous features such as low cost, small size, desirable performance, and ESD-protection capability. By way of an example, an MCM-packaged and ESD-protected RF single-pole-double-throw (SPDT) switch can be fabricated in an example 0.18 m bulk CMOS technology. A switch controller having a bandgap reference, low dropout voltage regulators (LDO), and level shifters can also be integrated, and such a configuration is shown to consume about 40 A from a 3.4 V supply.
(18) In some embodiments, the foregoing example switch can be based upon resistive body-floating technique. In the context of an example triple-well MOSFETs, such a switch can achieve an insertion loss of approximately 0.55/0.69/0.81 dB at approximately 0.9/1.95/2.45 GHz, respectively. TX-to-RX isolation of >28 dB and return loss of >14 dB can be achieved at these frequencies. The measured input 1 dB compression point (IP.sub.1dB) of approximately 21.5/21.1/20.8 dBm and input 3.sup.rd order intercept point (IIP.sub.3) of approximately 38.5/37.8/36.9 dBm can be accomplished at approximately 0.9/1.95/2.45 GHz, respectively. The example core switch size is approximately 0.02 mm.sup.2. At 2.45 GHz, the example switch shows a worst-case insertion loss of approximately 0.9 dB at 85 C. The example switch achieves an RF electrostatic discharge (ESD) rating of >4 kv for the 2 kV human body model (HBM) and >500 V for the 200 V machine model (MM).
(19) In some embodiments, desirable features such as the foregoing example performance features can be implemented in low-cost silicon bulk CMOS technologies for wireless communication systems. In such wireless systems, high power amplifier and double or multi-throw switch are two important front-end components that can be integrated to realize a more complete system-on-chip (SOC) for wireless transceivers. Switches with low insertion loss (IL), high linearity, and moderate to high power handling capability that were once implemented in III-V compound semiconductors such as GaAs pHEMT can be implemented in silicon bulk CMOS and silicon-on-insulator (SOI).
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(22) In some embodiments, the switching apparatus 100 can be part of a PA module. For example, a dual-band WCDMA PA module can include the foregoing high band (e.g., B1 at 1920-1980 MHz, B2 at 1850-1910 MHz, B4 at 1710-1785 MHz) and low band (e.g., B5 at 824-849 MHz, B8 at 880-915 MHz). The switch 102 can function as an input band select switch for switching between the high and low bands.
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(24) Referring to
(25) In both of the foregoing examples, insertion loss (IL), isolation, and linearity can be important performance parameters. For high power applications such as GSM, a requirement for power handling capability (IP.sub.1dB) can be even more stringent. Design for low IL on silicon can typically be achieved by selecting an optimal device size (especially on conductive silicon substrate) for a given technology, low substrate resistance (R.sub.sub), and high R.sub.sub. Depending on the target applications, design techniques for enhancing the power handling capability such as using high R.sub.sub, impedance transformation, LC tuned substrate biasing in a twin well process, and resistive body-floating can be utilized. For even higher power applications, multiple stacked devices with feed-forward capacitors and body-floating techniques can also be implemented.
(26) In some embodiments, an RF ESD-protected and area-efficient switch (e.g., an SPDT switch) with an integrated switch controller can be implemented in a laminated multi-chip-module (MCM-L). MCM-L package, featuring a laminate substrate with land grid array (LGA)-type perimeter pads, can provide advantageous features including high-density interconnect to achieve small package footprint, low ground RF inductance, and effective heat dissipation. MCM-L can also facilitate integration with other front-end components such as GaAs HBT PA and GaAs pHEMT LNA more conveniently.
(27) Although described in the context of SPDT configuration, one or more features of the present disclosure can also be implemented in other switch configurations. For example a switch can include more than one pole and/or a number of throws different than two.
(28) Example SPDT Switch Design
(29) An SPDT switch and integrated switch controller were implemented in TowerJazz standard 0.18 m bulk CMOS technology. This low-cost CMOS process includes four metal layers, deep n-well devices, and has a relatively low P.sup. substrate resistivity (.sub.si) of approximately 3 -cm.
(30) Schematic diagrams of the switch 102 and switch controller 106 are shown in
(31) In some implementations, the biasing of the switch 102 can be internally generated by an integrated switch controller 106 of
(32) In
(33) In some embodiments, at least some of the FETs of
(34) In the ON-state, V.sub.SB/V.sub.DB can be set to approximately 0 V for best IL (no bulk effect) for a given V.sub.G. High value unsilicided poly gate resistors (R.sub.G=approximately 40 k) can be used to further improve IL and mitigate the degradation in power handling capability at high input power.
(35) In some embodiments, a body-floating resistor (R.sub.BF) (e.g., R.sub.BF=approximately 25 k) can be introduced to ensure or increase the likelihood that the bulk terminal swings in accordance with the source/drain. Such a configuration can also allow the source/drain-to-bulk to be reversed-biased to achieve good linearity and avoid excessive capacitive coupling to the substrate. In some implementations, the latter can be important for attaining a low IL especially when operating at high frequencies.
(36) In the OFF-state, V.sub.SB/V.sub.DB can be biased at approximately 1 V in order to delay the turn-on of the junction diodes (C.sub.SB/C.sub.DB), thus improving the power handling capability. Consequently, the gate control voltage can be approximately 2.8 V for ON-state and approximately 0 V for OFF-state while the source and drain voltages can be biased at approximately 1 V (e.g., compromise between turn-on of V.sub.GD/V.sub.GS and gate oxide breakdown for the OFF devices).
(37) The nwell voltage (V.sub.nwell) can be biased at V.sub.DD (e.g., approximately 3.4 V, highest possible without using a voltage multiplier or charge pump) to keep C.sub.pwell-nwell and C.sub.nwell-psub reversed-biased while improving the compression characteristics at high power levels. The example switch design is based on the thin-gate 1.8 V devices. By adopting the resistive body-floating technique and proposed biasing strategy, the peak voltages at across gate oxide can stay below the TDDB breakdown voltage (3.2 V) of the 1.8 V devices.
(38) In some embodiments, and as shown in the example of
(39) In some implementations, the area of the example SPDT switch core 250 can be reduced by positioning at least some of the input (C.sub.in) and output blocking (C.sub.B) capacitors (e.g., see
(40) In some embodiments, the example SPDT switch can be implemented on a die utilizing CMOS technology.
(41) Example Experimental Results
(42) The example MCM-packaged switch 100 as described herein was mounted on an evaluation board 260 as shown in
(43) Between approximately 900 MHz and approximately 3 GHz, the switch achieves an input (TX port) return loss (RL) and output (Ant port) RL of >14 dB and >15 dB, respectively, from approximately 20 C. to approximately 85 C. (shown in
(44) As shown in
(45) As shown in
(46) The power handling capability (IP.sub.1dB) of the switch was conducted with an external broadband power amplifier module (Mini-Circuits ZHL-4240W). As shown in
(47) The ESD test was demonstrated using a handheld mini-zapper (KeyTek TPC-2A) with both HBM and MM inserts. The switch has successfully survived a RF ESD rating of >4 kV and >500 V (for both positive and negative ESD strikes) for the target 2 kV HBM and 500 V MM, respectively.
(48) Table 1 summarizes and compares the performance of prior published CMOS RF SPDT switches. Various values listed in Table 1 are approximate values.
(49) TABLE-US-00001 TABLE 1 Core Freq. RL IP.sub.1 dB IIP.sub.3 Area Ref. Process Technique (GHz) IL (dB) Iso (dB) (dB) (dBm) (dBm) (mm.sup.2) ESD Package This 0.18 m Resistive 0.9 0.55 TX: 28 14 21.5 38.5 0.02 >4 KV MCM-L work CMOS body-floating 1.95 0.69 TX: 31 17 21.1 37.8 (HBM) 2.45 0.81 TX: 33 21 20.8 36.9 >500 V (MM) A 0.5 m Low R.sub.sub 0.9 0.73 41.8 N.A 18.9 38.2 0.1 No SOIC CMOS B 0.18 m Impedance 0.9 0.97 35.4 14 26.3 37.7 0.1 No SOIC CMOS transformation 2.4 1.1 20.6 16 22.7 29.8 C 0.18 m LC-tuned 2.4 TX: 1.5 TX: 32 >12 28.5 N.A. 0.56 4 KV On- CMOS substrate RX: 1.6 RX: 17 (overall wafer biasing chip size) D 0.18 m Resistive body- 2.4 0.7 35 >19 21.3 30.3 0.03 No On- CMOS floating wafer E 0.18 m Body-floating 1.8 TX: 0.75 TX: 35 >14 33 N.A. 0.4 No COB CMOS and stacked RX: 1.1 RX: 20 device with feed-forward caps F 0.13 m Body-floating 0.9 TX: 0.5 TX: 37 20 31.3 42 0.11 No On- CMOS and feed- RX: 1.0 RX: 29 wafer forward caps
(50) In Table 1, the listed references A-F are as follows: A: F.-J. Huang and K. K. O, A 0.5-m CMOS T/R switch for 900-MHz wireless applications, IEEE J. Solid-State Circuits, vol. 36, no. 3, pp. 486-492, March 2001. B: F.-J. Huang and K. K. O, Single-pole double-throw CMOS switches for 900-MHz and 2.4-GHz applications on P-silicon substrates, IEEE J. Solid-State Circuits, vol. 39, no. 1, pp. 35-41, January 2004. C: N. Talwalkar, C. Yue, H. Guan, and S. Wong, Integrated CMOS transmit-receive switch using LC-tuned substrate bias for 2.4 GHz and 5.2 GHz applications, IEEE J. Solid-State Circuits, vol. 39, no. 6, pp. 863-870, June 2004. D: M.-C. Yeh, Z.-M. Tsai, R.-C. Liu, K.-Y. Lin, Y.-T. Chang, and H. Wang, Design and analysis for a miniature CMOS SPDT switch using body-floating technique to improve power performance, IEEE Trans. Microw. Theory Tech., vol. 54, no. 1, pp. 31-39, January 2006. E: M. Ahn, H.-W. Kim, C.-H. Lee, and J. Laskar, A 1.8-GHz 33-dBm P0.1-dB CMOS T/R switch using stacked FETs with feed-forward capacitors in a floated well structure, IEEE Trans. Microw. Theory Tech., vol. 57, no. 11, pp. 2661-2670, November 2009. F: H. Xu and K. K. O, A 31.3-dBm bulk CMOS T/R switch using stacked transistors with sub-design-rule channel length in floated p-wells, IEEE J. Solid-State Circuits, vol. 42, no. 11, pp. 577-584, November 2007.
CONCLUSION
(51) As described herein, a miniature CMOS RF SPDT switch (approximately 0.02 mm.sup.2) with MCM package and ESD protection can be provided. A biasing strategy generated by the integrated switch controller can also be implemented. By utilizing resistive body-floating technique in CMOS technology (e.g., a standard 0.18 m bulk CMOS technology), the power handling capability (IP.sub.1dB) of approximately 21.5/21.1/20.8 dBm can be achieved at approximately 0.9/1.95/2.45 GHz without resorting to voltage doubler, negative voltage generator (NVG), or stacked devices. The worst-case IL and isolation (TX mode) at 85 C. are <0.9 dB and >28 dB, respectively, from approximately 900 MHz up to approximately 2.45 GHz. The integrated switch controller consumes only 40 A from a 3.4 V supply. The switch has successfully passed the RF ESD rating of 2 kV human body model and 500 V MM, respectively.
(52) Example Applications
(53) As described herein, one or more features associated with the present disclosure can be implemented as a switch circuit. In some embodiments, the switch circuit can include one or more switches having one or more features as described herein. The switch circuit can also include a switch controller having one or more features described herein.
(54) As described herein, the foregoing switch circuit can be implemented on one or more semiconductor die.
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(56) The module 100 can further include one or more packaging structures 124 that can provide, for example, protection for the switch circuit 102. The module 100 can further include connection features 122 configured to provide electrical connections to and from the switch circuit 100.
(57) In some implementations, a device and/or a circuit having one or more features described herein can be included in an RF device such as a wireless device. Such a device and/or a circuit can be implemented directly in the wireless device, in a modular form 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, etc.
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(59) In the example wireless device 300 of
(60) In the example shown, the receiver 322 can be provided with the received (Rx) signal originating from an antenna 336 and routed through a switch 102 and a duplexer 332. Such a received signal can be amplified by an LNA (not shown) before being provided to the receiver 322.
(61) In the example shown, the transmitter 326 can generate the RF signal to be transmitted, and such an RF signal can be amplified by the power amplifier (PA) 328. Such an amplified RF signal can be routed to the antenna 336 through the duplexer 332 and the switch 102.
(62) As described herein, the switch 102 can include one or more CMOS devices, and be configured as described herein (e.g., resistive body-floating). The switch 102 can be a part of a module 100 that can also include an ESD protection circuit 104. In some embodiments, the module 100 can also include an integrated switch controller.
(63) The transmitter 326 and the receiver 322 are shown to interact with the baseband sub-system 308 through the RF interface 310. The baseband sub-system 308 can be configured to provide conversion between data and/or voice signals suitable for a user and RF signals associated with the transmitter 326 and the receiver 322. The RF interface 310 is also shown to be connected to a power management component 306 that is configured to manage power for the operation of the wireless device 300. Such power management can also control operations of the baseband sub-system 308 and other components or sub-systems.
(64) The baseband sub-system 308 is shown to be connected to a user interface 302 to facilitate various input and output of voice and/or data provided to and received from the user. The baseband sub-system 308 can also be connected to a memory 304 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.
(65) 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.
(66) 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.
(67) 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.
(68) 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.
(69) 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.