A 20 GS/s 5-Bit SiGe BiCMOS dual-nyquist flash ADC with sampling capability up to 35 GS/s featuring offset corrected exclusive-or comparators

The design and wafer probe test results of a 5-bit SiGe Flash ADC are presented. The integrated circuit, fabricated in a 200/250 GHz f rm T/ F, SiGe BiCMOS technology, provides a 5-bit analog to digital conversion with dual Nyquist operation at sample frequencies up to 20 GHz. Sampling clock rates are demonstrated as high as 35 GS/s. The ADC makes use of a comparator with an integrated exclusive-or function to reduce power consumption. The device also generates two half-rate interleaved outputs to ease data capture with laboratory equipment. An effective number of bits (ENOB) of nearly 5.0 is achieved for low-frequency input tones, dropping to 4.0 at 10 GHz.