The MD3880 is a 4-channel, variable gain amplifier (VGA) paired with a low noise amplifier (LNA) that delivers fully differential input and output for ultrasound applications. The 18.5dB gain of the LNA allows the whole channel to have 0.74nV/Hz of input-referred voltage noise at 5MHz. The LNA is capable of active impedance control to improve noise performance, provided that the applications can take advantage of input impedance matching. The output of the LNA is fed directly into the VGA without using an external coupling capacitor. The VGA is composed of a voltage controlled attenuator (VCA) and a programmable gain amplifier (PGA). The VCA can be continuously varied linear-in-dB by a control voltage (VTGC) from 0dB to a maximum 47dB. In addition, the gain of the PGA can be varied between four discrete settings.