1. Differential Active Inductor 2. Switched Bandpass Amplifier 3. Broadband Oscillator

Transkript

1 Markus Grözing, Manfred Berroth. Differential Active Inductor. Switched Bandpass Amplifier 3. Broadband Oscillator

2 Technology: Supply voltage: Frequency range: 0,5 µm CMOS,5 V DC to 5 GHz Status: processed and measured

3 Active Inductor Motivation I. Avoid spiral inductors require large die area potential magnetic field coupling layout cells and models often not available in standard-cmos foundry design kits fixed L value single-band operation fixed and low Q value on standard, low resistive CMOS substrates II. Achieve multi-band operation tuned L value switched L value 3

4 Circuit Concept Differential Gyrator Topology Transforms intrinsic capacitances to inductive behaviour U IN I IN C' G m C' Common mode and even harmonic rejection Broadband negative resistors available L f o = = C' G G m π m LC G m = G C' m G C' m 4

5 Circuit Implementation (RF) I IN U DD U IN I L +I Q Negative Resistance Loads Transconductance Stage G m I L I Q U DD I L +I Q Transconductance Stage G m Reference [] I L I Q 5

6 Circuit Implementation (DC) Reference [] Adding Current Mirrors P ref IIN P U IN P ' C P U DD I Qref N ref N NRref D D ' D NR D NR ' R Q N N NR N NRref C Q P ref I Lref P U P ' I Qref R L N ref N NRref D D ' D NR D NR ' R Q C L N ref N N NR N NRref C Q L-Tuning Current Mirrors Q-Tuning 6

7 Small Signal Model Differential mode equivalent circuit of the active inductor I IN C gd 3 Simplified circuit I IN C gd U ' U C g g m (-U ') g m ( U ') g C ' U U IN = U g m ( U ') -U ' -U C g C gd g m (-U ') g ' C U IN Differential mode equivalent circuit of half the active inductor Z IN / U IN = U ' I IN C g C g m U ' g m U ' C [ g + s( C + C )] [ g g + g g ] + s[ ( g g ) C + g ( C + C ) + g ( C + C )] + s ( C + C )( C + C ) m U = I m IN IN U ' = = I m m g U ' [ C ] L R C G C g g m m C g g g g m m 7

8 Tuning and Scaling of Inductance L L = Tuning µ CoxW gmd = I L ~ I L L ( long channel approximation) C L ~ gm gm g Inductance L ~ I L md MOSFETs size: Eq. circuit elements: Inductance: Scaling Power- / current consumption: Noise: W = M neu W alt C,C,gm,g m P DC, I I neff ~ L ~ DC ~ ~ M M M M f o = π gm g C C m Resonant frequency f o f o ~ ~ g md I L Saturation current: Dynamic range: DR = I I neff INsat / max (f ) f ~ I INsat ~ M M ~ M M 8

9 Layout IQ IQ UDD GND GND GND GND GND GND RF+ RF- GND GND GND IL GND Chip size: 300 µm x 700 µm Active inductor size (picture): 00 µm x 00 µm 9

10 Parameter-Analyzer (Biasing) I Lref,5 V I Qref I Qref Measurement Setup On-Wafer Probe Station DC- Block SMU SMU SMU 3 SMU 4 Port RF+ RF Hybrid Problems: measurement and calibration require matched paths RF+ and RF- (red lines) hybrid bandwidth is limited: 30 MHz to 3 GHz Σ Network- Analyzer Differential- Mode- Response Port Common- Mode- Response 0

11 Measurement and Simulation Results j j j0.5 j j0.5 j j0. j j0. -j0. -j0.5 Inductance L [nh] Symbol measurement Symbol simulation 800 Current I Lref [µa] 800 Current I [µa] Qref 0 0 Current I [µa] Qref j 3, -j -j0.5 Differential reflection coefficient Γ IN f = 00 MHz to 3 GHz Z 0 = 00 Ω Inductance L [nh] -j Symbol measurement Symbol simulation 00 Current I Lref [µa] 00 Current I [µa] Qref 0 0,7 Current I [µa] Qref 0,7 -j 3

12 Differential Active Inductor SUMMARY Current I Lref [µa] Current I Qref [µa] 0 0,7 Current I Qref [µa] 00,7 Current consumption I DC [ma],8,89 Power consumption P DC [mw] 3,0 4,73 Inductance L [nh] 3, 3 Resonant frequency f o GHz simulated: 5,6,9 Advantages: tunable inductance value L tunable quality factor Q high frequency operation Disadvantages: DC power consumption limited large signal performance (determined by DC) poor noise performance

13 Technology: Supply voltage: Bandpass frequencies: 0,8 µm CMOS,8 V Version : 00 MHz and GHz ( BP-frequencies) Version : 5 MHz to 875 MHz (7 BP-frequencies) Status Version : currently manufactured Version : development 3

14 Z in =75Ω Bandpass Amplifier Motivation S (f) S (f) ARD 50MHz GHz U in f f BP f f S 3 (f) S 4 (f) ARD ARD ARD 60MHz 60MHz f H(f) f f VCO Switched Bandpass Amplifier Mixer Lowpass Filter Cable modem: reduce amplifier bandwidth relax mixer and filter linearity requirements reduce power consumption 4

15 Circuit Concept (Version ) Large signal requirements: tuning of inductance not applicable switched inductance circuit concept L Active Inductor L Switch G ml C =C,ext +C p +C p C =C,ext +C p +C p C,ext U in G mv. U in R L U out Z in =75 Ω G ml Reference [3] Differential Common-Gate Amplifier L C =C,ext +C p +C p C,ext Active Inductor L 5

16 U DD N ref N ref Circuit Implementation (Version ) In Transconductance Amplifiers P ref, P P N NR,ref N N P ref, P P N NR,ref D D L L D D L L C i Ip I Q M On/Off M D NR D NR Negative Conductance L NR N NR L NR L NR L NR N NR D NR D NR Active inductors with sourcedegenerated differential amplifiers to enhance large signal performance I L N N I Q N NR N NR Reference [4] 6

17 Simulation Results (Version ) Bandpass frequency f BP 97 MHz 993 MHz Input impedance Z in (75 - j )Ω (69 - j 0)Ω Voltage gain V U 6,5 db 6,09 db Bandwidth B 60 MHz 80 MHz Input db-commpression point*) U in,db 7 mv 83 mv Current consumption I DC 9 ma 46,8 ma Noise 75 Ω F 75 8,7 db 5,8 db *) voltage amplitude 7

18 Simulation Results (Version ) 8

19 Technology: Supply voltage: Frequency range: Status: 0,8 µm CMOS,0 V GHz to 3,5 GHz currently manufactured 9

20 Broadband Oscillator Motivation Local Oscillator for Multi-bitrate serial transceivers i.e..0,.5,.0,.5, and 3.5 Gbit/s Broadband tuners i.e. cable modem Multi-band wireless transceivers 0

21 Circuit Design U DD U DD RF 0 HF 0 HF 90 RF Ω U SS U DD Oscillator Core U SS U DD 50 Ω RF 80 HF 80 HF 70 RF Ω U SS U SS 50 Ω U / V signal HF 0 in oscillator core 0 U 9 / V U / V t / ns t / ns t / ns signal after second inverter signal at 50 Ω load

22 Simulation Results Control voltage Equivalent control current Oscillation frequency Phase - noise MHz Overall DCcurrent **) Core DCcurrent Core voltage swing U Steuer I Steuer f osz PN [dbc/hz] I DC I DCcore U core,000 V 7,5 ma 4,9 GHz -80,86 50 ma 8,4 ma,77 V,000 V 3, ma 4,07 GHz -8,4 48 ma 7,6 ma,7 V 0,678 V 663 µa 3,4 GHz -83,39 43 ma 4,6 ma,46 V 0,600 V 30 µa,07 GHz -86,85 38 ma,4 ma, V 0,55 V 6 µa,00 GHz -9,69 35 ma 0,9 ma,03 V 0,500 V 75,3 µa 75 MHz -93,4 34 ma 0,6 ma 0,98 V 0,378 V 5,0 µa 94,3 MHz -94,63 9 ma 44 µa 0,78 V *) phase noise simulation was done with a voltage source applied to the control input U Steuer **) overall current consumption is mainly due to the four inverter chain line drivers

23 CONCLUSION Active inductor based circuits offer Advantages: broadband operation (tuned L) multiband operation (switched L) small chip area quadrature outputs (VCO) Drawbacks: DC power consumption limited large signal performance poor noise performance 3

24 Literature [] Thanachayanont, Apinunt and Payne, Alison: CMOS floating active inductor and its applications to bandpass filter and oscillator designs, IEE Proceedings Circuits, Devices and Systems, Special issue on High-frequency integrated analogue filters, Vol. 47, No., February 000 [] Grözing, Markus; Pascht, Andreas; Berroth, Manfred: A.5 V CMOS Differential Active Inductor with Tunable L and Q for Frequencies up to 5 GHz, 00 IEEE Radio Frequency Integrated Circuits (RFIC) Symposium, Phoenix, Arizona, May 0-, RFIC Digest of Papers, pp International Microwave Symposium Digest, Vol., pp [3] Akbari-Dilmaghani, Rahim and Payne, Alison: An RF CMOS Differential Bandpass Amplifier using an Active Inductor, IEE Colloquium on Systems on a Chip (Ref. No. 998/439), London, UK, pp. 6/-6, 998 [4] Krummenacher, Francois and Joehl, Norbert: A 4-MHz CMOS Continious-Time Filter with On-Chip Automatic Tuning, IEEE Journal of Solid-State Circuits, Vol. 3, No. 3, June 988 4

25 Acknowledgment The authors would like to thank Harald Parzhuber and Johannes Gerber, Hermann Mayerhofer Texas Instruments Deutschland GmbH Freising for providing us with processing capabilities and for help with the layouts and final design checks 5