A wide-band input buffer for 3GS/s 12bit time-interleaved ADC

The input buffer applied in the analog-to-digital converter (ADC) is to isolate the connection between the input signal and the sampling switch. In time-interleaved ADC structure for achieving high speed and high resolution, the distortion introduced by sampling circuit of sub-ADC channels affects the linearity of the input signal. A wide-band input buffer is proposed in this paper with 1.5GHz band-with and 10.4bit ENOB for a 3GS/s 12-bit Nyquist ADC with the LDOs as power supply. Two-stage buffer structure is applied in this paper for isolating the interference from different channels. Compensated capacitors are applied in the first buffer stage to alleviate the interference from the input signal. Complementary buffer structure is adopted in the second stage for power saving. The power consumption of this input buffer with 2V power supply and 1pF load capacitance is 246mW.