A Digitally-Calibrated 20-Gb/s 60-GHz Direct-Conversion Transceiver in 65-nm CMOS

Transcription

1 A Digitally-Calibrated 20-Gb/s 60-GHz Direct-Conversion Transceiver in 65-nm CMOS Seitaro Kawai, Ryo Minami, Yuki Tsukui, Yasuaki Takeuchi, Hiroki Asada, Ahmed Musa, Rui Murakami, Takahiro Sato, Qinghong Bu, Ning Li, Masaya Miyahara, Kenichi Okada, and Akira Matsuzawa (RMO2D-3)

2 Outline 2 Motivation Challenges and issues Proposed loop-back calibration - Free-run frequency cal. - I/Q mismatch cal. Measurement results Summary and conclusion

3 Motivation 3 60GHz CMOS direct-conversion transceiver for multi-gbps wireless communication IEEE ad specification 57.24GHz GHz 2.16GHz/ch x 4channels 16QAM 7Gbps/ch Ch.1 Ch.2 Ch.3 Ch.4 f [GHz]

4 Balun Baseband Block Balun Balun Block Diagram 4 RFAmp BBAmp 60GHz LNA RFAmp BBAmp LO Buff 36MHz Ref PLL 20GHz QILO QILO 60GHz LO Buff 60GHz RFAmp BBAmp PA RFAmp BBAmp Tx : 4-stage PA, Active mixer, BB Amp Rx : 4-stage LNA, Passive mixer, BB Amp LO : 60GHz QILO, 20GHz PLL

5 EVM [db] Challenges 5 Use wider frequency bandwidth and realize higher data rate. Better EVM is needed SiBeam CEA-LETI Tokyo tech This work(20gb/s) Tokyo Tech(10Gb/s) IMEC(7Gb/s) Year Panasonic (1.8Gb/s) UCB 16QAM QPSK

6 Phase error [deg.] Issues for EVM improvement 6 Gain flatness of TRx Phase noise IQ mismatch Target : IMRR > 30dB g t : Amplitude error ratio φ t : Phase error Amplitude error [db]

7 Conventional calibration method(1) 7 RF φ DAC : VGA φ : Phase shifter φ DAC RF calibration Can not adjust amplitude and phase errors independently. Fine calibration is difficult.

8 Conventional calibration method(2) 8 Analog BB φ DAC : VGA φ : Phase shifter φ DAC Analog BB calibration Can not adjust amplitude and phase errors independently. It is not easy to avoid frequency-dependent I/Q mismatch. Fine calibration is difficult.

9 Conventional calibration method(3) 9 Digital BB DAC φ : VGA φ : Phase shifter DAC φ Digital BB calibration Amplitude and phase can be adjusted independently. Accuracy depends on ADC/DAC/DSP resolution. Power consumption increase.

10 Balun Baseband Block Proposed calibration method 10 36MHz Ref PLL QILO LO Buff RFAmp BBAmp PA RFAmp BBAmp Amplitude error : Adjusted by RF VGA Phase error : Adjusted by LO Fine calibration can be realized.

11 60GHz QILO 11 36MHz ref. 20GHz PLL 60GHz QILO PFD CP LPF (27,28,29,30) 5 4 CML 19.44GHz 20.16GHz 20.88GHz 21.60GHz Q I 58.32GHz 60.48GHz 62.64GHz 64.80GHz Phase noise is improved by injection locking. The output frequency becomes desired one even if the QILO free-run frequency changes.

12 Phase analysis of Quadrature LO 12 I/Q phase difference can be controlled by Zi and Zq.

13 Schematic of QILO degree/code can be realized.

14 Proposed Calibration 14 Loop-back By loop-back and QILO, ftx and frx can be detected at the output of Rx.

15 QILO Frequency Calibration 15 Calibration steps (1)Searching lock-range of Rx QILO (2)Find Tx QILO ftx(free-run)= frx = 3fPLL (3)Find Rx QILO frx(free-run)= ftx = 3fPLL

16 Fine I/Q mismatch Calibration 16 Control DAC VgRFAmp VgMixer- V gmixer+ (4)Tx LO leakage (VgMixer) (Only Ich Rx is shown.) (5)Tx I/Q gain mismatch (VgRFAmp) (6)Tx I/Q phase mismatch (QILO) (7)Rx calibration same as (5)~(6)

17 IMRR [db] Amplitude error [db] Phase error [deg.] Measurement results (LO=58.32GHz) Frequency[GHz] Before After Before After Frequency [GHz] Before After Frequency[GHz] Amplitude error 0.3dB 0.2dB Phase error 26deg. 2.5deg. IMRR > 30dB SNR is improved by 10dB.

18 Tx Block[1] 18 4-stage PA MIM TL TL to antenna Up-conversion mixer from BB I/Q from LO Capacitive cross-coupling[2] [1] K. Okada, et al., ISSCC2012 [2] W.L. Chan, et al., ISSCC 2009

19 Rx Block[1] 19 4-stage CS-CS LNA from antenna Down-conversion mixer W=1mm x40 1mm x40 2mm x20 2mm x20 Gain peaking IF LNA

20 4.2mm Die Photo 20 65nm CMOS (RF) I Mixer LO Buff LNA Q Mixer PLL Q.OSC. Logic I MixerLO Buff PA Q Mixer Q.OSC.

21 Measurement Setup 21 Power supply RF board (Tx mode) RF board (Rx mode) Power supply AWG Agilent M8190A Laptop PC I/Q Control signals I/Q Control signals Laptop PC Oscilloscope Agilent DSA91304A DC supply Rx 6-dBi antenna Tx DC supply I/Q output (Rx) I/Q input (Tx) 16.3mm x 14.4mm

22 Rx measurement result 22 Tx Conversion Gain OP1dB Psat Power consumption Measurement 25dB 4.5dBm 9.6dBm 238mW(16QAM) Rx Input range Conversion Gain NF IIP3 Power consumption Measurement -76~-22dBm 7~23dB 4dB(Ch.1) -14dBm(Ch.1) 171mW(16QAM)

23 16QAM Communication 23 Channel Ch.1 Ch.2 Ch.3 Ch.4 Max rate (Ch.2) Constellation Spectrum Date rate* SNR EVM** 7.0Gb/s 7.0Gb/s 7.0Gb/s 7.0Gb/s 20.0Gb/s 23.7 db 22.6 db 22.5 db 20.7 db 17.6 db db db db db db *The roll-off factor is The bandwidth is 2.16GHz except for Max rate. **EVM through Tx and Rx boards.

24 Data rate [Gb/s] Performance Comparison direct-conversion other arch. This work Univ. of Toronto UCB NEC SiBeam, CEA-LETI Panasonic Toshiba Year Tokyo Tech IMEC UCB

25 Summary and conclusion 25 A 60-GHz direct-conversion wireless transceiver is implemented using 65nm CMOS process. Loop-backed calibration for I/Q mismatch is proposed and EVM < -25dB is realized. Covering full 4 channels with 16QAM. Max data rate of 20Gb/s is realized.

26 Thank you for your attention!