Abstract: An operational amplifier circuit having a first amplification stage that includes a differential pair of matches, low-noise transistors coupled in a common-emitter configuration, with a special reactive network in the emitter circuit of each transistor. Each reactive network comprises an inductor and a resistor, arranged in a shunt configuration, whereby at low frequencies the first stage has a relatively high gain and generates relatively low noise, and whereby at high frequencies the first stage has a relatively low gain and the amplifier circuit has sufficient phase margin to ensure stability.