A Low-Noise Linear TIA With 42-GHz Bandwidth for Single-Ended Coherent Optical Receivers

This letter demonstrates a low-noise linear transimpedance amplifier (TIA) for single-ended coherent optical receivers (ORXs) in 0.13- $\mu $ m SiGe BiCMOS. The TIA achieves relatively low noise, excellent linearity, and approximately unchanged bandwidth (BW) within a wide gain dynamic range by employing a cascade structure of an improved shunt-feedback (SFB) high- $R_{F}$ TIA Core optimized for high linearity and a variable-gain single-to-differential (VG-S2D) circuit with adjustable peaking. The measured results of the TIA exhibit 42-GHz −3-dB BW at 74-dB $\Omega $ maximum transimpedance gain $(Z_{T}) {_{,}}~37$ -dB gain dynamic range, 12.5-pA/ $\sqrt {\mathrm {(Hz)}}$ input reference noise (IRN) current density, and <3%> $2{^{{31}}} -1$ . The TIA draws 72-mA current from a 3.3-V voltage supply and takes up 1 mm2 of the chip area with all its testing pads.