Automatic Threshold Adjustment for Predictive Level Crossing Sampling Data Converters

This paper presented an automatic threshold adjustment circuit design for selecting the reference voltage levels in predictive level crossing sampling data converters. The automatic adjustment is based on counting the rate of triggered events in a timing window. The threshold voltage is then adaptively adjusted based on the event rate using closed-loop feedback. The threshold voltage increases while the event rate is too high, or vice versa. Such adjustment does not affect the reconstruction process, and the system does not need to store the change or absolute value of threshold voltage changes since the predictive level crossing sampling records the precise digital values at a fixed sampling clock rate. The event rate is adjustable depending on specific applications. Simulation results of ECG sensing are performed to demonstrate the performance of the proposed method. The proposed circuits provide a relatively stable output data throughput, which is friendly for the following data storage and processing devices.