Amplitude and Phase Noise in Nano-scale RF Circuits. Reza Navid May 14, 2007. Today, 45nm technology node is available for commercial production design. Several other nano-scale devices are also becoming available. Channel Length (Micron). Number of MOSFETs. CMOS Scaling Since Early 70s.
May 14, 2007
Several other nano-scale devices are also becoming available.
Channel Length (Micron)
Number of MOSFETsCMOS Scaling Since Early 70s
4004 Intel Processor
386 Intel Processor
Pentium IV Intel Processor
We study the white noise part of the drain noise in saturation.
dRClassical MOSFET Noise Formulation
It accurately predicts noise in long-channel MOSFETs.
Several methods are proposed to study this excess noise.
Today’s FETs, 50% Ballistic
Model: Ind=4kTgshgdoExcess Noise in Short-Channel FETs
We present a model based on ballistic MOSFET model.
Phase noise characterizes the frequency fluctuations.
This method is most suitable for formulation of phase noise in switching-base oscillators.
Without low-frequency poles
DTiDTjhas necessary andsufficient information for phase noise calculation.
With white noise
With colored noise
(presented elsewhere)Time-Domain Phase Noise Analysis
Passive noisy network
Ideal noise-free switch
Calculate jitter during each switching; Add them up to find total jitter.
This is suitable for switching-based oscillators.
Variance of one period
The 1st harmonic
The 3rd harmonic
Phase noise has peaks around odd harmonics, as expected.
Jitter-phase-noise relationship for nonzero jitter covariance is presented elsewhere [Navid, 2004].
Use time-domain jitter analysis for switching-based oscillators.
Very simple equations, but how accurate?
The difference is only a few dB; it increases in short-channel devices.
The unsymmetrical ring oscillator is only one of many possibilities.
Ring oscillators for functionality test
Fabricated in National Semiconductor’s 0.18mm CMOS process.
The oscillator with longer transistors has better spectral purity.
Oscillator with Longer transistors has 7dB smaller phase noise.
PumpFurther Research on Phase Noise
Use noise data to improve existing devices and build new ones.
This work is supported under an SRC customized research project from Texas Instruments and MARCO MSD center.
We would like to thank National Semiconductor Inc. for the fabrication of test chips.