Differential Transimpedance Amplifier for 25 Gb/s Optical Links in a 0.25 um SiGe BiCMOS technology

The design and experimental research of microwave monolithic integrated circuit (MMIC) of differential three-stage transimpedance amplifier (TIA) for 25 Gb/s optical communication links using 250 nm SiGe BiCMOS technology is presented. Designed TIA doesn't contain inductor peaking schematic for saving the chip area. To obtain the necessary bandwidth of TIA, the different techniques were used such as impedance matching and capacitive peaking circuit. The differential TIA provides measured gain of 17...20 dB in the band up to 20 GHz, group delay of 32±4 ps, maximum transimpedance gain of 62 dBΩ, and a 3-dB cut-off analog bandwidth of 20 GHz. Post-layout simulation shows the average input-referred noise of 27 pA/√Hz and output differential voltage swing of 0.45 V. Chip size of differential inductorless three stage TIA with pads is 0.7 × 0.7 mm
²
(0.3 × 0.4 mm
²
without pads).