Simulation and Optimization of CMOS Noise Parameter

Part III

 

The simulation and optimization of the noise models using SPICE as a simulator is implemented in UTMOST.(Figure 1).This new feature allows UTMOST users to select any available SPICE noise model (including BSIM3v3 Noise models) and optimize the Noise parameters using the global optimizer.

Figure 1. Measured versus simulation Flicker Noise characteristics

 

For accurate noise simulation, UTMOST uses the SPICE interface feature through VYPER and performs ".NOISE" analysis to obtain the flicker noise versus frequency characteristics (The SPICE input deck used for Noise simulation is presented in the November 1996 issue of the Simulation Standard and it is created automatically). The simulated data is overlayed on the measured data and the rms error is displayed on the simulated versus measured curves. (Figure 2).

Figure 2. Global optimization selecting noise parameters AF and KF.

 

After adding the proper Noise selector parameter (NLEV or NOIMOD in BSIM3) the AF, KF or NOIA, NOIB and NOIC (for BSIM3 model) can be selected in the parameters screen for global optimization.

Standard SPICE Flicker Noise Models:

These models are available for MOS Level1,2,3, BSIM1,BSIM2 and BSIM3v2models.

NLEV=0

 

NLEV=1

 

NLEV=2

 

BSIM3V3 Flicker Noise Models:

NOIMOD=1

NOIMOD=2

(for complete BSIM3v3 noise equations please refer to BSIM3V3 manual.)

 

The DC model of the transistor should be extracted prior to the NOISE modeling/optimization because the Noise model equations will utilize the simulated DC currents and conductances based on the DC model.