Modeling thermal induced inter-symbol interference of feedback digital to analog converters in delta-sigma modulators

We propose a method to model inter-symbol interference due to temperature mismatch in the transistors of a 1-bit digital to analog converter (DAC) which is used to feedback the quantizer output in a 2nd order continuous time delta-sigma (CTΔΣ) modulator. The degradation in the signal to noise ratio (SNR) with thermal induced inter-symbol interference is reported. The phenomenon is modeled with Verilog-A, and simulated using the Cadence Spectre circuit simulator. The model provides device designers with insight into device behavior which affect circuit and system performance.