A Gigasample/s 5 bit ADC with on-chip track & hold based on an industrial 1 mu m GaAs MESFET E/D process

To enhance the dynamic accuracy of high speed A/D conversion, a 5 bit flash converter with on-chip Track & Hold circuitry (T&H) has been developed. The design is based on TriQuint®s commercial 1 mu m GaAs E/D MESFET process. Dynamic characterization has been performed up to 1 GSps. An accuracy of 4.4 effective bits even at 1 GSps with full Nyquist input was achieved. A comparison showing the accuracy with T&H in operation and in tracking only mode is given. The outstanding performance is due to a carefully designed T&H and the use of differential SCFL in the converter.