Monolithic operational amplifier design with improved HF behaviour

The design of a monolithic operational amplifier, which combines a large bandwidth and a high output current, is described. The output stage is equipped with n-p-n transistors only, biased in class-AB by an internal common-mode feedback loop. The intermediate stage consists of a unity-current-gain split-frequency-band voltage level shift. An integrated version, intended for driving 50-/spl Omega/ coaxial line systems, achieves a bandwidth of 25 MHz and 100-mA output current. The principle described provides the possibility for achieving higher output currents.