High-Speed Flash Analog-to-Digital Converters: Circuit Techniques for Improving the Bandwidth and the Accuracy in Deep-Submicron Technologies

Flash Analog-to-Digital Converters (ADCs), targeting optical communication standards, have been reported in BiCMOS technology. CMOS implementation of such designs faces two challenges. The first is to achieve a high sampling speed, given the lower gain-bandwidth of CMOS technology. The second challenge is to handle the wide bandwidth of the input signal with certain accuracy. Although the first problem can be relaxed by using the time-interleaved architecture, the second problem remains as a main obstacle to CMOS implementation. Thus, this work analyzes the bandwidth-accuracy product of flash ADCs, and develops a circuit technique to improve the bandwidth-accuracy product of flash ADCs in deep submicron CMOS technologies. The performance improvement that can be attained due to the proposed circuit technique is demonstrated through the design and implementation of a 6-bit 1.6-GS/s flash ADC in 0.13-Um CMOS technology. This work is intended for researchers, graduate students, and practicing engineers.