A 5GS/s 8-bit ADC with Self-Calibration in 0.18 μm SiGe BiCMOS Technology

Abstract

A 5 GS/s 8-bit analog-to-digital converter (ADC) implemented in 0.18 μm SiGe BiCMOS technology has been demonstrated. The proposed ADC is based on two-channel time-interleaved architecture, and each sub-ADC employs a two-stage cascaded folding and interpolating topology of radix-4. An open loop track-and-hold amplifier with enhanced linearity is designed to meet the dynamic performance requirement. The on-chip self-calibration technique is introduced to compensate the interleaving mismatches between two sub-ADCs. Measurement results show that the spurious free dynamic range (SFDR) stays above 44.8 dB with a peak of 53.52 dB, and the effective number of bits (ENOB) is greater than 5.8 bit with a maximum of 6.97 bit up to 2.5 GS/s. The ADC exhibits a differential nonlinearity (DNL) of -0.31/+0.23 LSB (least significant bit) and an integral nonlinearity (INL) of -0.68/+0.68 LSB, respectively. The chip occupies an area of 3.9 × 3.6 mm2, consumes a total power of 2.8 W, and achieves a figure of merit (FoM) of 10 pJ/conversion step.