A Wideband mm-wave CMOS Receiver for Gb/s Communications Employing Interstage Coupled Resonators Federico Vecchi 1,2, Stefano Bozzola 3, Massimo Pozzoni 4, Davide Guermandi 5, Enrico Temporiti 4, Matteo Repossi 4, Ugo Decanis 1, Andrea Mazzanti 1, Francesco Svelto 1 (1) Università degli Studi di Pavia (2) Istituto Universitario di Studi Superiori di Pavia (3) Università degli Studi di Pavia, now with Broadcom (4) STMicroelectronics (5) STMicroelectronics, now with Broadcom
1 Outline Receiver requirements and architecture mm-wave receiver design Wideband LNA & RF Mixer VCO & Injection Locked Divider Experiments Conclusions
* ECMA International, High Rate 60 GHz Phy, MAC and HDMI PAL, Standard ECMA-387, 1st Edition, Dec. 2008. [Online]. 2 High Rate 60 GHz Phy Proposal* 2.16 GHz 1 2 3 4 57 58.32 60.48 62.64 64.8 66 f GHz Large RF bandwidth (~9 GHz minimum) Minimum Sensitivity: from -60 dbm (1 Gb/s) to -50 dbm (4 Gb/s) Maximum Noise Figure < 10 db Large LO tuning range required Very stringent phase noise at maximum data rate
Sliding IF Architecture First down-conversion to 1/3 of the received frequency à lower tuning-range required, relatively low power Only one PLL needed Injection Locked Dividers to generate I/Q half frequency signals 3
Gain Bandwidth product in single stage amplifier L Vout Vin M2 gmvin Vout L R1 C1 C2 R2 M1 V V out in = g R m R R R Z1 GBW = = 1// 2 C = C1+ C2 g m C Z2 Bandwidth can be traded for gain but gain at mm-wave is rare 4
Gain Bandwidth enhancement techniques De-coupling inductor Bandpass equivalent L L3 C3 R1 C1 C2 R2 Z1 L1 L2 Z2 Z1 Z2 Effective technique. Drawbacks: L 3 is a large inductance (0.5-1 nh) 3 inductors needed for Bandpass 5
Capacitively Coupled LC networks Capacitively Coupled Resonators Z1 L1 Cc L2 Z2 Norm. Gain [db] 0-2 -4-6 -8 C c Single LC Resonator -10 In-band ripple [db] Bandwidth enhancement 40 50 60 70 80 Freq. [GHz.] 0 1.2 1 1.7 2 2.0 3 2.2 Trade-off between in-band ripple and -3 db bandwidth Peak gain keeps constant 6
Vbias 3 Wideband Gain Stages 1 Stage 1 V 1 V 2 & 3 Stage RFIN L1 CPad L2 40µm 65nm 40µm 65nm Cap. Coupled Resonators Out In 20µm 65nm 20µm 65nm Cap. Coupled Resonators Out Ls 1 V Vbias C c 15 ff L3 L4 Gain Control adjusting V bias (from 27 to 14 db) Inductors: Coplanar Waveguides C1 Cc Out C2 7
Wideband RF Mixer MixQ+ MixI+ 40 GHz LO+ L2 Mixer In L1 LS LP CS 40 GHz LO- K L1 MixI- MixQ- L2 40 GHz LO+ Norm. Gain (db) Magnetic instead of capacitive coupling Inductor required for capacitive coupling > 1nH @ 20 GHz 0-1 -2-3 -4-5 -6 K 17 18 19 20 21 22 23 Freq. (GHz) 8
VCO ILFD V Bias Vtune 2X In L VCO Ip In bit2 bit1 bit0 4X 2X 1X Ip Div. Out+ LD M IN Div. In Div. Out- Fine tuning: NMOS in NWELL varactors Coarse tuning: switched MOM cap. Locking Range ~ 30% 9
Chip Micrograph Area: LNA RF & IF MIX. DIV. I VCO 2.4 mm 2 Power Consumption: 75 mw from 1 V DIV. Q Technology: STMicroelectronics 65nm CMOS Bulk Two versions: with Integrated VCO and with External LO 10
Gain & Noise Figure Gain (db) 40 35 30 25 20 15 10 5 0 55 60 65 70 10 9 8 7 6 5 4 3 2 Noise Figure (db) External LO Integrated VCO Frequency (GHz) Peak gain: 35 db over a ~13 GHz bandwidth Noise Figure lower than 6.5 db, with a minimum of 5.6 db VCO tuning range: 12.6% 11
S 11 (db) 0-5 -10-15 -20-25 Input Match & 1 db Comp. Point 50 55 60 65 70 Freq. (GHz) Input Match better than -14 db on the whole bandwidth Input 1 db Compression Point: -39 dbm (High Gain) -21 dbm (Low Gain) Gain Variation: from 35 to 14 db Ouput Power (dbm) Ouput Power (dbm) 0-5 -10-15 -20 0-5 -10-15 -20 @ 60 GHz High Gain -50-45 -40-35 Input Power (dbm) @ 60 GHz Low Gain -30-25 -20-15 Input Power (dbm) 12
Phase Noise Measurement RF MIXER IF MIXER BUFFER Phase Noise (dbc/hz) -85-90 -95-100 -105-110 -115-120 -125 60 f GHz LNA 40.1 PN f GHz 40 GHz VCO From 60 GHz Carrier 20 GHz 1 10 100 Frequency Offset (MHz) /2 0.15 f GHz 60 PN + 20log10 40 PN + 3.5 db Measured Phase Noise: -115 dbc/hz @ 10 MHz from 60 GHz Carrier VCO Phase Noise: -118.5 dbc/hz @ 10 MHz from 40 GHz 13
Performance Summary Voltage Gain (High Gain) 35.5 [db] Voltage Gain (Low Gain) 14 [db] Noise Figure (High Gain) 5.6 6.5 [db] Noise Figure (Low Gain) 12 [db] RF Bandwidth >13 [GHz] Image Rejection 80 [db] Tuning Range 12.6 [%] I/Q Mismatch < 3 [deg] LO Phase Noise (from 60GHz) -90 @ 1MHz -115 @ 10MHz [dbc/hz] Input 1 db Comp. Point (High Gain) -39 [dbm] Input 1 db Comp. Point (Low Gain) -21 [dbm] Power 75 [mw] Supply Voltage 1 [V] Technology 65 CMOS [nm] 14
15 Conclusions Inter-stage coupling is effective to enhance the gain-bandwidth product of gain stages in mm-wave receivers The realized solution proves a very good sensitivity over a wide band of 56GHz 68GHz A remarkable phase noise has been achieved with a VCO tuning of 12.6%
16 Acknowledgments This work has been partially supported by Italian national funding programs PRIN, contract # 2007B5RZLE and FIRB, contract # RBA06L4S5.
Comparison with State of the Art This Work Scheir Parsa Tomkins JSSC08 JSSC09 JSSC09 Voltage Gain [db] 35.5 30 22 14.7 Noise Figure [db] 5.6 6.5 7.1-9.8 5.7-7.1 5.6-7.2 RF Bandwidth [GHz] 13 N. A. 4 10 Image Rejection [db] 80 N. A. N. A. N. A. Tuning Range [%] 12.6 16.6 6.8 * N. A. ** I/Q Mismatch [deg] < 3 N. A. 2.1 N. A. LO Phase Noise [dbc/hz] -90 @ 1MHz -115 @ 10MHz from 60GHz -85 @ 1MHz from 50GHz -84 @ 1MHz from 60GHz N. A. ** Input 1 db Comp. Point [dbm] -21-29.9 *** -27.5-22 Power [mw] 75 65 36 151 Supply Voltage [V] 1 1.2 1.2 1.2 Technology [nm] 65 CMOS 90 CMOS 90 CMOS 65 CMOS * No varactors tuned varying the supply and/or placing external conductive plate atop the LO ** External LO *** High Gain Mode
IF Mixer 20GHz LO+ Out- IFin+ Total Gain: 9 db Gain control variation: from 9 to 2 db Out+ 20GHz LO+ 20GHz LO- IFin- Vcm Gain (db) 10 9.5 9 8.5 8 Double Balanced topology with active loads and CMFB Cascaded by a gain control stage Current consumption: 9 ma Upper Sideband Lower Sideband 0 0.5 1 1.5 Freq. (GHz)
I & Q Downconverted Waveforms I/Q Error: < 3