Systems, devices, and methods for continuous time signal processing
View Patent ↗The present disclosure shows new mechanisms for sampling an input signal. In particular, some embodiments of the present disclosure include a new type of a level-crossing sampling mechanism called a derivative level-crossing sampling (D-LCS). At a high level, D-LCS involves quantizing the derivative of an input signal when the derivative of the input signal crosses one of the quantization thresholds. For certain class of signals, the derivative of the input signal can vary at a slower speed compared to the amplitude of the input signal. Therefore, by sampling the derivative of the input signal, instead of the input signal itself, the number of samples per unit time can be reduced.
1. A circuit system comprising:
a differentiator configured to receive an input signal and to provide a derivative of the input signal; and
a quantizer coupled to the differentiator, configured to receive the derivative of the input signal and to sample the derivative of the input signal when the derivative of the input signal crosses one of a plurality of quantization thresholds to provide a quantized derivative of the input signal; and
a continuous time digital signal processing block coupled to the quantizer, configured to receive the quantized derivative of the input signal and process the quantized derivative of the input signal to provide a derivative of an output signal; and
an integrator coupled to the continuous time signal processing block, configured to receive the derivative of the output signal and to integrate the derivative of the output signal to provide the output signal.
2. The circuit system of claim 1 , wherein the quantizer is configured to represent the quantized derivative of the input signal using a per-level representation.
3. The circuit system of claim 2 , wherein the quantizer comprises a flash analog-to-digital converter.
4. The circuit system of claim 1 , wherein the quantizer is associated with a finite offset voltage, and wherein the circuit system further comprises a feedback system configured to compensate for the finite offset voltage associated with the quantizer.
5. The circuit system of claim 1 , wherein the continuous time digital signal processing block comprises at least one analog multiplier and a summation block.
6. The circuit system of claim 1 , wherein the continuous time digital signal processing block is configured to receive the quantized derivative of the input signal represented in a per-level representation.
7. The circuit system of claim 1 , wherein the integrator is associated with a finite offset voltage, and wherein the circuit system further comprises a feedback system configured to compensate for the finite offset voltage associated with the integrator.
8. The circuit system of claim 1 , wherein the input signal comprises a bio-signal from a human body.
9. A method of processing an input signal using a circuit system, the method comprising:
receiving, at a differentiator, the input signal;
determining, using the differentiator, a derivative of the input signal;
determining, using a quantizer coupled to the differentiator, a plurality of time points at which the derivative of the input signal crosses one of a plurality of quantization thresholds; and
sampling, using the quantizer, the derivative of the input signal at the plurality of time points to provide a quantized derivative of the input signal processing the quantized derivative of the input signal to provide a derivative of an output signal;
wherein sampling the derivative of the input signal at the plurality of time points to provide the quantized derivative of the input signal comprises determining a per-level representation of quantized derivative of the signal;
wherein integrating, using an integrator, the derivative of the output signal to provide the output signal.
10. The method of claim 9 , wherein the plurality of quantization thresholds comprises a first quantization threshold, a second quantization threshold, and a third quantization threshold, wherein the first quantization threshold, the second quantization threshold, and the third quantization threshold are consecutive thresholds, and wherein a first difference between the first quantization threshold and the second quantization threshold is different from a second difference between the second quantization threshold and the third quantization threshold.
11. The method of claim 9 , wherein the quantizer is associated with a finite offset voltage, and wherein the method further comprises compensating for the finite offset voltage associated with the quantizer using a feedback system.
12. The method of claim 9 , wherein the integrator is associated with a finite offset voltage, and wherein the method comprises compensating for the finite offset voltage associated with the integrator using a feedback system.
13. A communication system for communicating over a communication channel, the communication system comprising:
a differentiator configured to receive an input signal and to provide a derivative of the input signal;
a quantizer coupled to the differentiator, configured to receive the derivative of the input signal and to sample the derivative of the input signal when the derivative of the input signal crosses one of a plurality of quantization thresholds to provide a quantized derivative of the input signal; and
a transmission block coupled to the quantizer, configured to receive the quantized derivative of the input signal and to transmit the quantized derivative of the input signal over the communication channel; and
wherein a continuous time digital signal processing block coupled to the quantizer, configured to receive the quantized derivative of the input signal and to process the quantized derivative of the input signal to provide a processed quantized derivative of the input to the transmitter, wherein the transmission block is further configured to transmit the processed quantized derivative of the input signal over the communication channel.
14. The communication system of claim 13 , comprising a receiver, configured to receive the quantized derivative of the input signal from the communication channel, further configured to integrate the quantized derivative of the input signal to provide an output signal.
15. The communication system of claim 13 , wherein the input signal comprises a bio-signal from a human body.