Paper presentation Ultra-Portable Devices Paper: Hooman Darabi, - PowerPoint PPT Presentation

Paper presentation – Ultra-Portable Devices Paper: Hooman Darabi, Janice Chiu, A noise Cancellation Technique in Active RF-CMOS Mixers. Journal of Solid-State Circuits, vol. 40, no. 12, pp. 2628- 2632, Dec 2005. (compact version also at ISSCC, feb. 2005) Presented by: Carl Bryant 2009-12-01 Paper Presentation - Ultra Portable Devices 1

Outline • Introduction • Noise sources • Noise improvement • Implementation • Results • Summary 2009-12-01 Paper Presentation - Ultra Portable Devices 2

Introduction • Double balanced mixer • 1/f (flicker) noise important for direct conversion receiver • Most 1/f noise comes from switch pair 2009-12-01 Paper Presentation - Ultra Portable Devices 3

Introduction 1/f noise Noise White noise Frequency • 1/f noise produced when drain current nonzero • Noise large for low frequencies • Narrowband receiver may operate below total noise corner 2009-12-01 Paper Presentation - Ultra Portable Devices 4

Noise sources Switch fully ON LO Switch fully OFF Both switch devices conducting • Switch pair contributes no noise when fully on/off • Noise introduced during zero crossings • Noise modulates zero crossings 2009-12-01 Paper Presentation - Ultra Portable Devices 5

Noise sources 2009-12-01 Paper Presentation - Ultra Portable Devices 6

Noise Improvement • Reduce flicker noise component: • Increasing switch size – Slower switches – Increases capacitive load of input devices • Reduce width of noise pulses: • Faster LO slopes – Increses power consumption in LO buffers – Supply voltage limits LO amplitude 2009-12-01 Paper Presentation - Ultra Portable Devices 7

Noise improvement • Reduce height of noise pulses • Reducing switch stage current • Increases switch stage impedance 1/g m • More current shunted through parasitic capacitance • Reduces bandwidth and linearity 2009-12-01 Paper Presentation - Ultra Portable Devices 8

Noise improvement (this work) • Reduce switch stage current dynamically • Starve switch stages only during switching event • Detect switch event by monitoring source voltage 2009-12-01 Paper Presentation - Ultra Portable Devices 9

Noise improvement 2009-12-01 Paper Presentation - Ultra Portable Devices 10

Implementation 2009-12-01 Paper Presentation - Ultra Portable Devices 11

Implementation • Injection devices should be dimensioned to turn on/off • Large injection devices add parasitic capacitance • Since the noise is reduced, switch pair can be made smaller • TSMC 0.13 μ m 2009-12-01 Paper Presentation - Ultra Portable Devices 12

Results 2009-12-01 Paper Presentation - Ultra Portable Devices 13

Results 2009-12-01 Paper Presentation - Ultra Portable Devices 14

Summary • Significant improvement of flicker noise • Little negative impact on performance 2009-12-01 Paper Presentation - Ultra Portable Devices 15

Chip photo 2009-12-01 Paper Presentation - Ultra Portable Devices 16

Further reading • Darabi H., Abidi A.A.,“Noise in RF -CMOS mixers: a simple physical model”, Solid-State Circuits, IEEE Journal of , vol.35, no.1, pp.15-25, Jan 2000 2009-12-01 Paper Presentation - Ultra Portable Devices 17