CMOS Linear Mixer Design for High Performance Receiver Applications

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CMOS Linear Mixer Designfor High Performance
Receiver Applications
Jiming Jiang 22 Sept 2005 Department of
Engineering, University of Cambridge
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Design Issue

• Non-linearity
• Bandwidth
• Power Consumption
• Conversion Gain
• Noise

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Target Specification
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Non-linearity Third Order Inter-modulation
Distortion
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Analysis Methods for Prediction of Non-linearity

• Taylor series
• Simple approach but not adequate for high
  frequency analysis
• Harmonic balance
• Accurate but only suitable for numerical work, eg
  computer simulation
• Volterra series
• Accurate but complicated procedure demanded

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IMD3 using Volterra Series
Common Source
Differential Pair
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DiscussionsLinearity improvement methods
Discussion 1 Linearity Enhancement based on
degeneration component

Inductance Negative real number Decrease
Capacitance Positive real number Increase
Discussion 2Linearity based on A1(s) and T1
Increasing A1(s) -gt Linearity decrease Increasing
T1 -gt Linearity increase
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Linearity Enhancement With Capacitance and
Degeneration Inductance
With source and degeneration impedance
With external capacitance and degeneration
inductance
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Conclusion
Capacitive
Inductive
Resistive
Good Linearity Noisy resistance
Good Linearity No noise Added
Bad Linearity Noisy Source
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IIP3 With Swept Inductance and Capacitance Value
NB Simulation is based on AMS
0.35um BSIM3 Model
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Simulation Circuit Setup
Capacitance degeneration
Inductance degeneration
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Without Improvement (IIP310dbm)
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With Improvement (IIP323.5dBm)
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Proposed Linearity Enhancement method

Pre-Distortion