Abstract: A Peltier cooling system for solid-state operational amplifiers reduces the bias current and allows the amplifier to perform at a level previously attained only by vacuum tube operational amplifiers. The amplifier is cooled with a Peltier junction substantially below the ambient to control the temperature very closely to a fixed value. A solid-state temperature detector is placed in thermal contact with the operational amplifier substrate. The sensor output, which is proportional to he absolute temperature of the operational amplifier, is fed to the temperature control circuitry. The control circuitry compares the sensor current with a temperature set point current, and the difference is used to control the cooler current.