System architecture and key components of a multi-Giga-Hertz A/D converter with HBT

This paper reports the design and performance of a very fast 6-bit ADC system with GaAs HBT technology. The ADC system consists of a track/hold circuit and an ADC. The track/hold circuit employs an open-loop architecture and uses Schottky barrier diodes for a diode switch, and achieves 3 GS/s operation with better than 6-bit linearity. The 6-bit ADC employs folding/interpolation architecture to reduce hardware and power maintaining the high-speed operation, and it achieves DC linearity better than 7-bit.