Waveform Memory for Real-Time FPGA Test of Fiber-Optic Receiver DSPs

Abstract

Verification of advanced circuit implementations poses many challenges. For complex digital signal processing (DSP) circuits, logic simulations may be prohibitively slow when non-stationary scenarios are considered. A real-time emulation technique like the Fiber-on-Chip (FoC) approach can significantly speed up DSP logic verification. However, a potential weakness with this type of emulation is that it does not use data obtained from experiments, but synthetically creates test data. We introduce a waveform memory, which can be integrated with FoC systems and similar emulators, and which allows measured waveforms to be stored and fed to DSP circuits under test. We perform real-time FPGA experiments where we evaluate a carrier-phase recovery (CPR) module that is tested using either waveform data or synthetic data. Our results for the two different data sets show that the CPR module behaves similarly, both qualitatively and quantitatively, which indicates that the synthetic phase-noise model is a valid replacement of measured data.