A 10-GS/s multibit delta-sigma analog-to-digital converter in an InP HBT technology

Continuous time delta-sigma (CTΔΣ) analog-to-digital converters (ADCs) are capable of sampling at much higher rates than discrete time ΔΣ converters. This makes heterojunction bipolar transistor (HBT) technologies excellent candidates for the implementation of fast CTΔΣ ADCs. Due to linearity considerations, all HBT-based ΔΣ ADCs known to us incorporated a single-bit digital-to-analog converter (DAC). Here, we present a multibit lowpass ΔΣ ADC based upon the InP HBT technology, which incorporates an internal resolution of 2 bits. The ADC was clocked at 10 GHz, its total power consumption was 1.9 W, and it obtained a signal-to-noise ratio (SNR) of 44.1 dB at signal bandwidth of 312.5 MHz.