Low-Power SiGe BiCMOS Transimpedance Amplifier for 25-GBaud Optical Links

We propose a new circuit for the realization of transimpedance amplifiers (TIAs), targeted at reducing the input-referred noise of the TIA or alternatively increasing the bandwidth, without increasing the power dissipation. An intensive theoretical analysis of the method is given. A prototype chip is fabricated in 0.25- $\mu\hbox {m}$ SiGe BiCMOS technology. The TIA has a gain of 71 $\hbox {dB}\Omega$ , a bandwidth of 20.5 GHz, and an average input-referred current noise density of 18 $\hbox {pA}/\surd \hbox {Hz}$ . The circuit operates from a 2.5-V supply, and power dissipation is 57 mW.