Ultrafast sampling using low temperature grown GaAs MSM switches integrated with CMOS amplifier for photonic A/D conversion

摘要

Within the past few years, various photonic A/D conversion systems have achieved speed and resolution performance far surpassing conventional mixed signal technology, lending merit to this hybrid approach. In our system, we utilize an optically triggered, electrical sample and hold scheme with low temperature (LT) grown GaAs MSM switches. The switch is attached to a transmission line and samples the input electrical signal onto a hold capacitor when optically activated by a short-pulse laser. An electrical AID converter then digitizes the held signal. By time-interleaving a number of these channels, the aggregate sampling rate of the system is increased, with the larger bandwidth requirements being placed on the input sample and hold. The short carrier trapping time and relatively high mobility of the LT GaAs material provide broadband sampling capability with good optical sensitivity.