Amplitude adaptive ASDM without envelope encoding

In this paper a method of encoding the signals by using Amplitude Adaptive Asynchronous Sigma-Delta modulator (AA-ASDM) scheme without an additional envelope encoding of the signal is proposed. According to AA-ASDM, the time-varying envelope function of the input signal is used in the feedback loop to reduce the switching rate of the output trigger and thus the power consumption of the circuit. In previous work, the signal and its envelope function were encoded and transmitted separately, thus resulting in inefficiency, since two signals instead of one were required to be transmitted. In order to solve this inefficiency, in this paper it is proposed to select such a time-varying envelope function which does not require additional encoding and transmission, and still be able to recover the original signal from the obtained time sequence. The proposed method is particularly advantageous for signals with wide dynamic range.