Evolutionary based simplified symbolic PSRR analysis of analog integrated circuits

Abstract

Parasitic interactions through the power supply lines put major limitations on the performance of analog amplifiers, especially in the mixed analog---digital integrated circuits. In this paper, a general method is presented for the symbolic analysis of power-supply rejection ratio (PSRR) in CMOS analog operational amplifiers. Since the complexity of the symbolic expressions grows exponentially with the circuit size, it is necessary to utilize simplification techniques for the analysis of practical circuits. We introduce an evolutionary criterion based on genetic algorithm for the efficient simplification of symbolic PSRR expressions. In contrast to the classical simplification criteria which simplify the different polynomials separately, the main advantage of the proposed criterion is to consider the correlation between different polynomials and different symbolic terms. The proposed methodology guarantees the accuracy of the simplified PSRR expressions in contrast to the exact ones, with a predictable error rate. Comparison of the numerical results extracted from the simplified symbolic PSRR expressions with HSPICE over two analog amplifiers demonstrates the efficiency of the proposed methodology. Simulations also show that the proposed evolutionary-based simplification technique outperforms the existing simplification criteria.