A 5-b 10GS/s A/D Converter for 10-Gb/s Optical Receivers

In high bit rate optical communication systems operating at 10 Gb/s or beyond, some of the impairments such as chromatic dispersion (CD) and polarization-mode dispersion (PMD) cause degradation of the signal seriously. Electrical domain approach is more desirable than optical compensating techniques because of its potential for compact and cost-effective implementation. Especially, adaptive equalization approach would be more desirable, where an analog-to-digital converter (ADC) is used to sample and convert the analog signal into digital data that are eaily manipulated by the following adaptive digital equalizer, as shown in Figure 1. In the paper, we present a 5-b fully differential, flash-type ADC with data update rate over 10 GS/s processed in SiGe BiCMOS technology. The ADC shows a 4.2-b (measurements) at 904 MS/s on 1 V p-p differential input, and a 3.4-b (simulations) with 5.28 GHz full-scale sinewave at 10 GS/s. The ADC maximally consumes about 3.7 W from both -3.8 V (analog) and -3.0 V (digital) supplies.