Spectral Estimation Based Acquisition of Incoherently Under-sampled Periodic Signals: Application to Bandwidth Interleaving

Acquisition of periodic waveforms is an integral part of characterizing high speed system performance. Various techniques are used to reduce the equipment cost, dominated by the cost of the digitizer. Incoherent under-sampling provides an attractive solution for signal acquisition. However, due to the aliasing present in under-sampled signal and the windowing effects, high resolution spectral estimation is difficult. This is especially true when under-sampling is combined with techniques such as bandwidth interleaving to extend the bandwidth of the test setup beyond the track and hold bandwidth. In this paper we propose a high resolution spectral estimation technique and propose a new setup that combines incoherent under-sampling with the bandwidth interleaving without requiring a synchronization with the signal clock. This enables waveform acquisition with bandwidth greater than the sampling track-and-hold bandwidth.