A 1-GHz bipolar class-AB operational amplifier with multipath nested Miller compensation for 76-dB gain

A 1-GHz operational amplifier with a gain of 76 dB while driving a 50-/spl Omega/ load is presented. The equivalent input noise voltage is as low as 1.2 nV//spl radic/Hz. This combination of extremely high bandwidth, high gain, and low noise is the result of a three-stage all-n-p-n topology combined with a multipath nested Miller compensation. Using 10-GHz f/sub T/ n-p-n transistors, the realizable bandwidth could be of the order of 2-3 GHz. However, bond-wire inductances restrict the useful bandwidth to 1 GHz. The amplifier occupies an active area of 0.26 mm/sup 2/ and has been realized in the bipolar part of a 1-/spl mu/m BiCMOS process.