A 56-Gb/s 10.46- $\text{pA}{/}$ ${\!}\sqrt{\text{Hz}}$ Input Noise Linear TIA With 31-dB Dynamic Range in 22-nm CMOS

Abstract

This brief proposes a novel optical receiver featuring wide bandwidth and low noise, with a flat frequency response across a large dynamic range without bandwidth peaking. A wide dynamic range transimpedance input stage (WDR-TIS) is proposed as the input-stage amplifier of proposed transimpedance amplifier (TIA). This structure maintains a relatively constant bandwidth during high transimpedance gain dynamic range while delivering adequate noise performance. A three-stage variable gain amplifier (VGA) provides a dynamic range up to 22 dB with excellent linearity, and can accommodate an input current up to $2.8~{\text {mA}}_{\text {pp}}$ . Measurement results show that the proposed optical receiver provides an electrical transimpedance gain ( $\boldsymbol {Z}_{\text {T}}$ ) of 40.9 to 72.6 dB $\boldsymbol {\Omega }$ with bandwidth beyond 18.8 GHz and input-referred noise density (IRND) current of $10.46~{\text {pA}{/}{\!}\sqrt {\text {Hz}}}$ . The total harmonic distortion (THD) is less than 4% for the output amplitude up to $450~{{\text {mV}}_{\text {ppd}}}$ . The core of proposed optical receiver achieves a power dissipation of 85 mA from 1.5 V supply and occupies an area of $0.53\times 0.36$ mm² in 22 nm standard CMOS process.