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Paper presentation – Ultra-Portable Devices
Paper:
Presented by:
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)
Carl Bryant
2009-12-01 1Paper Presentation - Ultra Portable Devices
Outline
• Introduction
• Noise sources
• Noise improvement
• Implementation
• Results
• Summary
2009-12-01 2Paper Presentation - Ultra Portable Devices
Introduction
2009-12-01 Paper Presentation - Ultra Portable Devices 3
• Double balanced mixer
• 1/f (flicker) noise important for direct conversion receiver
• Most 1/f noise comes from switch pair
Introduction
2009-12-01 Paper Presentation - Ultra Portable Devices 4
1/f noise
White noise
Nois
e
Frequency
• 1/f noise produced when drain current nonzero
• Noise large for low frequencies
• Narrowband receiver may operate below total noise corner
Noise sources
2009-12-01 Paper Presentation - Ultra Portable Devices 5
LO
Switch fully ON
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
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
2009-12-01 Paper Presentation - Ultra Portable Devices 8
• Increases switch stage impedance 1/gm
• More current shunted through parasitic capacitance
• Reduces bandwidth and linearity
• Reduce height of noise pulses• Reducing switch stage current
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 0.13μm
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
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