An 800 MSps Track and hold using a 0.3 µm AlGaAs-HEMT-technology

A feedforward T/H was developed as part of a 100 MSps / 10 bit successive approximation ADC using a 0.3 µm AlGaAs-HEMT process. This T/H is able to operate up to a clock frequency of 3 GHz and reaches a THD >= 60 dB up to the Nyquist frequency of the ADC at the nominal clock frequency of 800 MHz. This was realized using a special circuit structure with a signal path and a reference path and a new diode bridge switch with an additional auxiliary bridge.