Analysis and Design of Transimpedance Amplifiers for Optical Receivers

Chapter 4Receiver Fundamentals

In this chapter, we examine the optical receiver at the system level and discuss how its performance is affected by the noise and bandwidth of receiver circuits such as the TIA. We start by analyzing how noise in the receiver causes bit errors. This leads to the definition of receiver sensitivity. We calculate and compare the sensitivity of different types of receivers (p–i–n, APD, optically preamplified, coherent, and analog receivers). We discuss how to measure the bit-error rate (BER) and the sensitivity. Then, we introduce the concept of noise bandwidth and apply it to calculate the total input-referred noise. Next, we define the required optical signal-to-noise ratio (required OSNR), which is important for receivers in amplified lightwave systems. After that, we introduce the concept of power penalty, which is useful to quantify receiver impairments such as intersymbol interference (ISI). Finally, we look at the trade-off between noise and ISI in NRZ and RZ receivers and draw conclusions about the best choice of the receiver's bandwidth and frequency response.

Additional receiver impairments are discussed in Appendix C: Timing Jitter and Appendix D: Nonlinearity. The mitigation of ISI is discussed in Appendix E: Adaptive Equalizers and Appendix F: Decision Point Control. The correction of bit errors is addressed in Appendix G: Forward Error Correction.

4.1 Receiver Model

The basic receiver model used for this chapter is shown in Fig. 4.1 ...