Macromodeling of FET/bipolar operational amplifiers

Macromodels for MOSFET-bipolar and JFET-bipolar integrated circuit operational amplifiers are developed. The macromodel parameters are found from typical data sheet or easily measured characteristics. Comparisons of macromodel performance with a device-level computer simulation and with characteristics obtained experimentally for three representative FET/bipolar operational amplifiers (CA 3140, LF 355, and TL 081) are presented. The macromodel is shown to be accurate enough for general purpose applications. The advantages of the macromodel of reduced circuit complexity and reduced central processing unit (CPU) time are demonstrated.