Integrated AlGaAs/GaAs HBT high slew-rate and wide band operational amplifier

We report the design, fabrication, and test results of a wide band and high slew-rate voltage-mode operational amplifier using AlGaAs/GaAs HBT's. To select higher carbon doping concentration is more effective in reducing base resistance, and lower emitter doping concentration possess a smaller input capacitance to improve the device speed. The HBT operational amplifier has provided 500 V//spl mu/s high slew-rate, only 8 ns setting time and about 2 GHz unity-gain frequency. Common mode rejection ratio (CMRR) values of this operational amplifier are in the order of 70 dB with a small DC input voltage offset 5 mV, and the open-loop gain is about 40 dB. >