TCSIM: A top-down approach to mixed-signal circuits and systems design

Design methodologies have evolved over the years, especially due to shrinking transistors in CMOS technology. This has encouraged the use of behavioural modelling in Matlab and Simulink over other less accurate or time consuming options for design and simulation, hence the development of TCSIM (Top-down Circuit Simulation In Matlab). The following components are modelled for this initial prototype: the output voltage limitation of operational amplifiers (opamps), the current limitation and parasitic capacitances of operational transconductance amplifiers (OTAs), the finite and nonlinear variation of on resistance in switches, and the nonideal behaviour of switched capacitor (SC) integrators. This is complemented by an analysis of the noise in these circuits. The models are verified with Cadence simulations and are shown to be both accurate and easy to map to the circuit level. It is also possible to optimize complete systems to efficiently meet specifications. The top-down methodology is demonstrated with the design of a delta-sigma (DeltaSigma) analog-to-digital converter (ADC) to be both accurate and simple with TCSIM.