Differential VCO and Differential VCO and Frequency Tripler using - PowerPoint PPT Presentation

Differential VCO and Differential VCO and Frequency Tripler using SiGe SiGe Frequency Tripler using HBTs for the 24 GHz ISM Band for the 24 GHz ISM Band HBTs Mina Danesh*, Frank Gruson, Peter Abele, Hermann Schumacher * - Microwave Communications (Montreal, Canada) University of Ulm (Germany) 2003 RFIC Symposium June 9, 2003 Philadelphia, PA, USA RFIC 2003 Mina Danesh 1

Outline Outline Outline • Project overview • 8 GHz Differential VCO • Circuit Design • Measurement Results • Differential Frequency Tripler • Circuit Design • Measurement Results • VCO/Tripler MMIC • Measurement Results RFIC 2003 Mina Danesh 2

24 GHz ISM Band 24 GHz ISM Band Overview Overview • ISM Band: 24 - 24.25 GHz • Applications • Short-range wireless data link • Short range radar sensors (automotive) • Project goals • Low cost, reliable, fully integrated, energy efficient MMIC • Attractive SiGe technology (low-cost, high integration) • System Design Requirements • LO source to drive a mixer at 0-10 dBm LO power • LO tuning range >= 250 MHz • IF frequency range: 500 MHz to 1 GHz • FM / BPSK modulation � carrier phase noise: -80 dBc/Hz at 100 kHz RFIC 2003 Mina Danesh 3

LO Source Design LO Source Design Frequency source building block IC LO Vcont Frequency VCO Buffer tripler Frequency Upstream or Loop Phase divider (static + downstream filter detector programmable ) conversion • Differential design advantages: • Easier integration with frequency divider and Gilbert-type mixer • Better common-mode rejection • 2x maximum voltage swing • Reduced crosstalk & immunity from substrate • Higher differential Q if substrate loss dominates RFIC 2003 Mina Danesh 4

Atmel SiGe1 HBT Process SiGe1 HBT Process Atmel Initial SiGe1 Process: HBT (0.8 � m) technology 2 Al metal layers � f T = 30 GHz � BV ce0 = 6 V Nitride passivation layer oxide Metal2 1.5 � m HBTS Metal1 3.7 � m (selectively implanted collector ) � f T = 50 GHz Si substrate � BV ce0 = 3 V 300 � m 20 � -cm RFIC 2003 Mina Danesh 5

Differential VCO Circuit Differential VCO Circuit Design - - Schematic Schematic Design Vcc Ls Ls Vcc Vcc Vct Rcb Rcb Q3 Q4 Cn Cn Rf Rf Cv Cv Cf Cf Cb Cb Q6 Cbo Q5 Cbo OUT+ OUT- Q2 Q1 Reb Reb Rbb Rbb Vbb Vbb Iee Ree Emitter follower Emitter follower Differential VCO RFIC 2003 Mina Danesh 6

VCO Circuit Design - - Layout Layout VCO Circuit Design Differentially driven symmetric inductor P P Emitter Emitter G G follower follower Varactors S- S+ HBTS transistor pair G G Biasing 380 � � P 380 � � RFIC 2003 Mina Danesh 7

VCO Design – – Symmetric Symmetric VCO Design Inductor Inductor Layout generated by custom script RFIC 2003 Mina Danesh 8

VCO Design – – Symmetric Symmetric VCO Design Inductor Inductor Underpass in M1 M2 105 Port3 � � Zd = Z11 + Z22 – Z12 – Z21 w = 10 � � s = 3 � � N = 3 Port1 Port2 Q diff = Re[Zd] / Im[Zd] Reference: M. Danesh and J. R. Long, “Differentially Driven Symmetric Microstrip Inductors”, IEEE Trans. MTT , L ind = 0.8 nH (meas); 0.76 nH (sim) vol. MTT-50, no. 1, Part II, pp. 332-341, R dc � � � � � � � Jan. 2002. RFIC 2003 Mina Danesh 9

VCO Tuning Measurements VCO Tuning Measurements 40 MHz/V 160 MHz/V 270 MHz Vcc - vo RFIC 2003 Mina Danesh 10

VCO Phase Noise Results VCO Phase Noise Results -90 dBc/Hz @ 100 kHz RFIC 2003 Mina Danesh 11

VCO Performance Summary VCO Performance Summary •Frequency of operation: 4.4 dBm 7.95 – 7.75 GHz •Tuning voltage: 0 – 2.7V > - 30 dBc •Tuning sensitivity: 50 MHz/V •Output power: 4.4 dBm +/- 0.1 •Biasing voltage: 3.3V •Total current: 27 mA •Phase noise: -90 dBc/Hz @100 kHz •Harmonic rejection: > 30 dBc RFIC 2003 Mina Danesh 12

Frequency Tripler Design Frequency Tripler Design Vcc Ls Ls Cs Cs R= 30 � � GND Cb2 GND Cb2 380 OUT+ OUT- � � Cb1 Cb1 Pout+ Pout- Q2 Q1 IN- IN+ Rbb Rbb HBTS transistor pair Pin- Pin+ Iee Ree Vbb Vbb Characteristics : GND GND Biasing • Differential transistor pair Symmetric Inductor • high input voltage swing 150 � � w = 10 � � ; s = 3 � � • limiting amplifier Rdc � � � � � 2*Ls = 0.32 nH • square wave at output Q at 24 GHz = 13 • rich in odd harmonics RFIC 2003 Mina Danesh 13

Frequency Tripler Frequency Tripler Measurements Measurements Pin = 0 dBm RFIC 2003 Mina Danesh 14

Frequency Tripler Frequency Tripler Measurements Measurements RFIC 2003 Mina Danesh 15

Frequency Tripler Frequency Tripler Conversion Loss Conversion Loss I = 28 mA -9 dB V = 3.3 V DC pwr = 92.4mW RF-RF efficiency: 12% GaAs comparison: Optimal conversion loss of – 4 dB RFIC 2003 Mina Danesh 16

VCO/Tripler MMIC VCO/Tripler MMIC VCO inductor 600 � � Buffer Buffer VCO VCO o/p VCO o/p Tripler Tripler o/p Tripler o/p Tripler inductor 300 � � RFIC 2003 Mina Danesh 17

VCO / Tripler Results VCO / Tripler Results Frequency VCO output Tripler output (GHz) power (dBm) power (dBm) 7.82 / 7.81 0.5 / 2.6 -9 / -8.8 15.6 / 15.6 -33 / -32 -30 / -37 23.5 / 23.4 -34.5 / -33 -10 / -4 Values in italics indicate simulated results. Frequency tripler phase noise degradation ~ 20log(3) = 9.5 dB Measured spot phase noise @ 100 kHz ~ -80 dBc/Hz RFIC 2003 Mina Danesh 18

VCO / Tripler Tuning Range VCO / Tripler Tuning Range 100 MHz/V 420 MHz 270 MHz/V RFIC 2003 Mina Danesh 19

VCO- -Tripler LO Tripler LO VCO Performance Summary Performance Summary Frequency of operation 23.5 – 23.08 GHz Tuning voltage 0 – 2.5V Tuning sensitivity 100 - 270 MHz/V Output power -10 dBm +/- 1 dB Biasing voltage 3.3V Total current 55 mA Phase noise -80 dBc/Hz @100 kHz Even Harmonic rejection > 20 dBc RFIC 2003 Mina Danesh 20

Conclusion Conclusion • Integrated variable frequency source for the 24 GHz ISM Band • Taking advantage of differential circuits • Frequency tripler built in a SiGe process • Optimization of the VCO at a lower frequency • Overall frequency source performance enhancement • Feasibility of a low-cost solution RFIC 2003 Mina Danesh 21