Automated Design of DC-Coupled Broad-Band Amplifiers Monolithic

A design automation program has been written to optimize the design of dc-coupled monolithic broad-band amplifiers. This program adjusts dc conditions, device geometry, and all passive elements to obtain the maximum small-signal bandwidth consistent with specified low-frequency gain and quiescent power dissipation. The principal features of the program are a frequency-response analysis subroutine based on a nodal admittance matrix formulation, a precise response sensitivity analysis using the adjoint network, and an optimization subroutine based on the Fletcher-Powell algorithm. Two complete design examples, based on the series-series feedback triple and series-shunt feedback pair, are presented. For typical integrated-circuit processing, a maximum bandwidth on the order of 100 MHz is obtained for these designs with a voltage gain of 34 dB and 96-mW power dissipation.