1. 1 Low Phase Noise Oscillators for MEMS inductors Sofia Vatti Christos Papavassiliou

2. 2 Summary Two sets of oscillator circuits prototyped for EPSRC-STEP FASTSAN: Fixed frequency single phase Oscillators for MEMS integration Voltage controlled Oscillators for MEMS integration Quadrature Oscillators for MEMS integration MEMS characterisation test patterns Same circuits with planar inductors provided by the process Extensive on-chip calibration facilities: MEMS inductor characterisation pattern Monolithic inductor characterisation pattern RF wafer probe calibration structures All oscillator circuits ESD protected

3. 3 Measurements on “chip2” (novel VCO, AMS 0.35) Proposed topology: -oscillates at 1.952 GHz -phase noise as State of the Art -extra tunability through internal loop supply (+varactors)

4. 4 measurements - 1: frequency tuning Varactor control: 100 MHz Reference Supply Control: VDD2 30 MHz tunability ---- linearity improved

5. 5 measurements – 2 phase noise Varactor control Reference Supply Control: V DD2 -Phase Noise performance maintained when tuning via VDD2. -Integrated inductor Q=3 @ 2GHz (low compared to literature) -Power consumption = 50mW (high compared to literature)

6. 6 FastSAN “chip 3” micrograph MEMS Inductor Integration pad

7. 7 Oscillator example DC probe card (10 needles) : Power & frequency band switching RF probes Calibration patterns UMC 0.18 micron CMOS 200um

8. 8 VCO Measurements: circuit -No varactors in the tank -Control voltages switch in caps C0- C4 to change frequency bands - 3nH foundry inductor Breaking the loop with Caps provides access to gates of NMOS. AC is still coupled. DC gate bias is set from M3-M5, M4-M6, by controlling VDD2. VDD2 control from 0.8V-1.8V provides up to 300MHz tuning.

9. 9 VCO measurements: tuning range - 1.5GHz total range: 3.8 to 5.3 GHz - Switch-in capacitor approach - 5 coarse-tuning regions - Fine tuning (200 to 300MHz) provided by bias mechanism - No varactors used Reference Supply Control Gradually switching in the caps: 5 switches Phase noise: <-70dBc/Hz @100kHz

10. 10 Conclusions Collaboration with OSD Group CAS role: –Electronic Design for CMOS – MEMS co-integration –Novel LC oscillator topologies have been prototyped and tested –Performance comparable to state of the art OSD role: –Develop Hetero-Integration Technology Project status: –Final stages of CMOS+MEMS assembly