Analysis and Design of Transimpedance Amplifiers for Optical Receivers

Chapter 8Advanced Transimpedance Amplifier Design II

In the following, we explore ways to reduce the noise by replacing the noisy feedback resistor of the shunt-feedback TIA with a capacitive, optical, or active-feedback device. Then, we discuss the current-mode TIA in which the voltage amplifier is replace by a current amplifier. After that, we look at photodetector bootstrapping, a technique to reduce the detector's effective capacitance. Finally, we turn to TIAs for specialized applications, such as burst-mode receivers and analog receivers.

8.1 TIA with Nonresistive Feedback

Capacitive-Feedback TIA with Differentiator

In medium- and low-speed applications, a large portion of the TIA's input-referred noise current originates from the feedback resistor(s) (cf. Section 6.3). In principle, we can get rid of this noise by replacing the feedback resistor with a noise-free feedback capacitor. But unfortunately, this replacement turns the TIA into an integrator, which severely distorts the signal waveforms.

One solution to this problem is to follow the integrator with a differentiator, as shown in Fig. 8.1(a), thus equalizing the frequency response [1, 2]. Assuming large voltage gains for and , the low-frequency transimpedance of this circuit is [1]

8.1

and its input-referred noise ...