Analysis of regeneration time constant of dynamic latch using Adomian Decomposition method

This paper presents Adomian Decomposition based analysis of regeneration time constant of CMOS dynamic cross-coupled latch. A CMOS dynamic cross-coupled latch, which is a nonlinear system, is typically analyzed by linearizing it around an operating point to arrive at regeneration time constant. However, the time domain behavior obtained using the linear analysis deviates from the actual behavior of the latch. Thus, circuit simulators like SPICE and Spectre solve the nonlinear differential equations numerically to obtain the time domain behavior. These numerical solutions neither give a closed form expression of the regeneration time-constant nor do they give an expression of time domain behavior in closed form. Adomian Decomposition Method (ADM), however, can be used to obtain the complete time-domain behavior and the regeneration time-constant. ADM expresses the solution of a nonlinear differential equation in a manner similar to Taylor series approximation of a polynomial. The paper first introduces the concept of ADM and then applies it to RC linear circuits. c. Simulations show good agreement between Cadence based and ADM based time domain behavior.