A 6-bit 2.5-GS/s Time-Interleaved Analog-to-Digital Converter Using Resistor-Array Sharing Digital-to-Analog Converter

This paper presents a 6-bit 2.5-GS/s time-interleaved (TI) successive-approximation-register (SAR) analog-to-digital converter (ADC) that uses a resistor-array sharing digital-to-analog converter (RASD). By applying the input folding technique in the input stage and utilizing the flash-assisted TI-SAR ADC with the proposed RASD, the static power dissipation is reduced by 69%. ON-chip and OFF-chip calibration techniques are used to compensate the interchannel error sources. The prototype was fabricated in a 65-nm CMOS process technology. The peak integral nonlinearity and differential nonlinearity are measured as 0.52 and 0.51 LSB, respectively. At 2.5 GS/s, a signal-to-noise and distortion ratio (SNDR) of 18.6/31.9 dB and a spurious-free dynamic range (SFDR) of 23.7/42.1 dBc are measured before and after the calibration at the Nyquist input frequency with 1 Vpp-diff input signal, and the figure of merit is 0.27 pJ/conversion-step. This chip consumes 22 mW at 1.2-V supply and occupies 0.27-mm² area.