Low-Power RF Integrated Circuit Design Techniques for Short-Range Wireless Connectivity

Transcription

1 Low-Power RF Integrated Circuit Design Techniques for Short-Range Wireless Connectivity Marvin Onabajo Assistant Professor Analog and Mixed-Signal Integrated Circuits (AMSIC) Research Laboratory Dept. of Electrical and Computer Engineering Northeastern University, Boston, USA Website: ES2 Northeastern University Planning Grant Meeting November 30, 207

2 Introduction Outline Motivation for low-power RF CMOS circuit design Technical challenges Linearity improvement method for subthreshold low-noise amplifiers Theory and simulation Measurement results Integrated RF front-end chip Low-noise amplifier and mixer Measurement results Conclusions 2

3 Health Monitoring Application Example: Wireless Body Area Network (WBAN) Circuit design challenges (in addition to performance, size, reliability, cost) Reduction of power consumption to extend battery lifetime Resilience to interference signals 3

4 Subthreshold RF Design Considerations Power efficiency Higher transconductance-to-drain current (g m /I D ) ratio than in the strong inversion region Suitable for low supply voltages Lower transition frequency (ω T g m /C gg ) Capacitance C gs does not dominate in the subthreshold region Other parasitic capacitances (C gd and C gb ) should be carefully taken into account 4

5 Subthreshold RF Design Considerations (cont.) For a weakly nonlinear transconductance amplification stage: i d g v g v g v 2 3 gs 2 gs 3 gs where: g = g m (linear transconductance gain) g 2 and g 3 are the 2 nd -order and 3 rd -order nonlinearity coefficients g I V D GS, g I V D 2, g I D 3 GS V GS Subthreshold linearity characteristics Sign change of g 3 /g High g 3 /g ratio (signal distortion) 5

6 Linearized Subthreshold Low-Noise Amplifier (LNA) 3 3 rd -order nonlinearity (distortion) cancellation Without active components minimization of power consumption No cross-coupling is required permits the use of a single-ended architecture C.-H. Chang and M. Onabajo, Linearization of subthreshold low-noise amplifiers, in Proc. IEEE Intl. Symp. on Circuits and Systems (ISCAS), pp , May

7 3 3rd-Order Intermodulation Intercept Point (IIP3) where: Analysis result: ),2 ( ) ( ) ( A H R IIP s g g ob 3 ),2 ( ) (2 ) ( g g g g g g ob ) ( ) ( ) ( ) ( ) ( ) ( 3 x x gs gd C j C j g ] [ C j gd x 7

8 IIP3 Evaluation with Various L g2 and C gd2_ext Values 8

9 Chip Micrographs of Fabricated Linearized Subthreshold LNAs AMSIC Research Lab (a) Work (b) Work 2 (a) Dongbu 0.μm CMOS technology C.-H. Chang and M. Onabajo, Low-power low-noise amplifier IIP3 improvement under consideration of the cascode stage, in Proc. IEEE Intl. Symp. on Circuits and Systems (ISCAS), May 207. (b) IBM 0.3μm CMOS technology 9

10 LNA Printed Circuit Board with IIP3 Tuning Functionality 0

11 Comparison with Other Subthreshold LNAs Reference Work + Work 2 + [] + [2] + [3] # [4] $ [5] f c [GHz] S 2 [db] NF [db] IIP3 [dbm] P db [dbm] P DC [μw] Tech. [μm] Layout [mm 2 ] (# of Ind.) (3) 0.24 (3) 0.77 () 2.0 (4) (3) 0.63 (2) () FOM measured in package (cascode topology) # probe measurements (single-transistor topology) $ measured in package (self-biased inverter topology) measured in package (inductive feedback topology) FOM Gain[ abs] IIP3[ mw ] f [ GHz] 0 log ( NF[ abs] ) PD[ mw ]

12 References [] A. V. Do, C. C. Boon, M. A. Do, K. S. Yeo, and A. Cabuk, A subthreshold low-noise amplifier optimized for ultra-low-power applications in the ISM band, IEEE Transactions on Microwave Theory and Techniques, vol. 56, no. 2, pp , Feb [2] H. Lee and S. Mohammadi, A 3GHz subthreshold CMOS low noise amplifier, in Proc. Radio Frequency Integrated Circuits (RFIC) Symp., June [3] B. G. Perumana, S. Chakraborty, C.-H. Lee, J. and Laskar, A fully monolithic 260- μw, -GHz subthreshold low noise amplifier, IEEE Microwave Theory and Wireless Component Letters, vol. 5, no. 6, pp , June [4] T. Taris, J. Begueret, and Y. Deval, A 60μW LNA for 2.4 GHz wireless sensors network applications, in Proc. Radio Frequency Integrated Circuits (RFIC) Symp., June 20. [5] A. Shameli and P. Heydari, A novel ultra low power low noise amplifier using differential inductor feedback, IEEE European Solid State Circuit Conference (ESSCIRC), Sep. 2006, pp

13 Low-Power RF Front-End Combined LNA & mixer to demonstrate the compatibility of the linearization techniques Proof-of-concept measurements L. Xu, C.-H. Chang, and M. Onabajo, A 0.77mW 2.4GHz RF front-end with -4.5dBm in-band IIP3 through inherent filtering, IEEE Microwave and Wireless Components Letters (MWCL), vol. 26, no. 5, pp , May

14 Die Micrograph of the RF Front-End (0.3μm CMOS Technology) 4

15 Measurement Setup Measured voltages at the intermediate frequency (IF) outputs Simulated voltages at the IF outputs 5

16 Performance Summary and Comparison 6

17 References [6] A. Selvakumar, M. argham, and A. Liscidini, Sub-mW Current Re-Use Receiver Front- End for Wireless Sensor Network Applications, IEEE J. Solid-State Circuits, vol. 50, no. 2, Dec [7]. Lin, P.-I. Mak, and R. P. Martins, A 0.4-mm 2.4-mW 59.4-dB-SFDR 2.4 GHz igbee/wpan Receiver Exploiting a Split-LNTA + 50% LO topology in 65-nm CMOS, IEEE Trans. on Microwave Theory and Techniques, vol. 62, no. 7, pp , Jul [8]. Lin, P.-I. Mak and R. P. Martins, A 2.4-GHz igbee Receiver Exploiting an RF-to-BB- Current-Reuse Blixer + Hybrid Filter Topology in 65-nm CMOS, IEEE J. of Solid-State Circuits, vol. 49, pp , June 204. [9] F. hang, K. Wang, J. Koo, Y. Miyahara, and B. Otis, A.6mW 300mV-Supply 2.4GHz Receiver with -94dBm Sensitivity for Energy-Harvesting Applications, in Int. Solid-State Circuits Conf. Tech. Dig., pp , Feb [0] B. W. Cook, A. D. Berny, A. Molnar, S. Lanzisera, and K. S. J. Pister, Low-power 2.4- GHz Transceiver With Passive RX Front-End and 400-mV Supply, IEEE J. Solid-State Circuits, vol. 4, no. 2, pp , Dec

18 Conclusion Subthreshold LNA linearization method to enable low-power design Extra inductor and capacitor for nonlinearity cancellation Negligible impact on power, noise and gain design tradeoffs IIP3 improvement: db -db compression point improvement: db Linearization techniques for low-power RF front-ends in short-range wireless communication devices Adaptation of the linearization technique for low-power active mixers Demonstrated with a low-power linearized RF front-end The design methods do not require an auxiliary amplifier circuit Suitable for low-power applications 8

19 Thank You. Questions are Welcome. Marvin Onabajo Analog and Mixed-Signal Integrated Circuits (AMSIC) Research Laboratory Dept. of Electrical and Computer Engineering Northeastern University, Boston, USA Website: The projects were supported in part by the National Science Foundation under awards # and #4523.

20 Appendix

21 Examples of Low-Power Wireless Communication Standards AMSIC Research Lab Wireless Personal Area Network (WPAN) Wireless Body Area Network (WBAN) Bluetooth Low Energy (BLE) IEEE (igbee) IEEE Frequency Range GHz 2.4 GHz, 868 MHz, 95 MHz, GHz, GHz(US), (400/868/95/950 MHz) Data Rate Mbps 20 Kbps 250 Kbps 75.9 Kbps 97.4 Kbps Network Size undefined up to devices up to 256 devices Range 0-75 m 0-00 m 2-5 m 2

22 Generalized Linearization Approach AMSIC Research Lab Commonly used technique for LNAs: one or more auxiliary amplifiers to cancel the 3 rd -order nonlinearity term of the main amplifier Main amplifier: typically in strong inversion Auxiliary amplifier: in strong inversion or weak inversion (depending on the topology) α 3 = α 3m + α 3a = 0 Main drawback: extra power consumption and increased complexity due to the DC biasing circuitry for the auxiliary amplifier(s) 22

23 3 Analysis with and without L g2 and C gd2_ext Small-signal equivalent circuit for the second stage (with M 2 ) and load: Conventional LNA: 3conv ( ) g j m C 2 gs 2 Linearized LNA: 3_ Lin ( ) j C g m2 gd 2 d j C ( j C gs2 gs2 j C gd 2 j C ( g m2 gd 2 2 C j C gs2 gs2 C )( d gd 2 d ) g2 ) g2 23

24 IIP3 Simulation Results >db IIP3 improvement for input power levels below -35dBm 24

25 LNA IIP3 vs. C gd2_ext Comparison (Simulation vs. Measurement Results) IIP3 vs. tuning code 25

26 Linearized Subthreshold Mixer AMSIC Research Lab R d R d IF - IF + LO + M 2 M 3 M 3 M 2 LO + X C C LO- X C C RF + M M RF - Structure with cross-coupling capacitors (C C ) Negative capacitance generation to partially cancel the parasitic capacitance at X Terminal impedances can be adjusted to enhance IIP3 Enables wideband linearization L. Xu, K. Wang, C.-H. Chang, and M. Onabajo, Inductorless linearization of low-power active mixers, in Proc. IEEE Intl. Symp. on Circuits and Systems (ISCAS), pp , May

27 Differential Front-End with LNA and Mixer: Measured S Parameter, Voltage Conversion Gain and Noise Figure (NF) Voltage gain from the LNA input to mixer output (IF = 0MHz) and S vs. frequency Voltage gain and NF vs. LO power 27

28 Differential Front-End with LNA and Mixer: Linearity Performance Measurements (IIP3 & IM3) IIP3 of the RF front-end IM3 dbc with input power of -3.5dBm (including 0.3dB loss from the buffer stage) 28