Design and implementation of random sample circuit in digital phosphor oscilloscope

The ever increasing demand for the high-speed, EMC digital design is putting forward higher challenges towards the oscilloscope. As the latest generation of oscilloscope, Digital Phosphor Oscilloscope (DPO) has become an all-purpose waveform acquisition and analyzing instrument. According to the Nyquist sampling theorem, the acquisition ability of DPO is constrained by the sampling rate. The random sampling technique could make up for this, which makes the whole system achieving a high equivalent sampling rate and temporal resolution. The design and implementation of a random sampling circuit in DPO is provided in this paper. The design could mainly be divided into two parts: Time measurement circuit and Waveform reconstruction circuit. The above design has already been used in the prototype of 1 Gsps DPO and reaches an equivalent sampling rate of 50 Gsps, meets the performance requirements of the DPO system well.