Low power always-on microphone using power reduction techniques
An audio activity detector device is disclosed. The audio activity detector device comprises a closed loop feedback regulating circuit that supplies an input signal representative of a time-varying voltage signal to a quantizer circuit, wherein the quantizer circuit, as a function of the input signal, converts the input signal to a quantizer discrete-time signal; a first circuit that, as a function of the discrete-time signal, determines a key quantizer statistic value for the quantizer discrete-time signal; and a second circuit that, as a function of the key quantizer statistic value, determines a signal statistic value for the input signal and a gain control value.
1. A device comprising:
a closed loop feedback regulating circuit that supplies an input signal representative of a time-varying voltage signal to a quantizer circuit, wherein the quantizer circuit, as a function of the input signal, converts the input signal to a quantizer discrete-time signal;
a first circuit that, as a function of the discrete-time signal, determines a key quantizer statistic value for the quantizer discrete-time signal; and
a second circuit that, as a function of the key quantizer statistic value, determines a signal statistic value for the input signal and a gain control value.
2. The device of claim 1 , wherein the key quantizer statistic value represents a root mean square value.
3. The device of claim 1 , wherein the key quantizer statistic value represents a standard deviation value.
4. The device of claim 1 , wherein the key quantizer statistic value represents a peak-to-peak value.
5. The device of claim 1 , wherein the key quantizer statistic value represents an instantaneous amplitude value.
6. The device of claim 1 , wherein the key quantizer statistic value represents the input signal.
7. The device of claim 1 , wherein the first circuit determines the key quantizer statistic value based on the discrete-time signal and a system clock value.
8. The device of claim 1 , wherein the second circuit determines the signal statistic value and the gain control value based on the key quantizer statistic value and a system clock value.
9. The device of claim 1 , wherein the gain control value is supplied to the closed loop feedback regulating circuit.
10. The device of claim 1 , wherein the input signal is a first input signal, and wherein the closed loop feedback regulating circuit receives a second input signal representative of an unregulated signal of varying signal amplitudes.
11. The device of claim 1 , wherein the quantizer circuit is a multi-bit quantizer circuit.
12. The device of claim 1 , wherein the gain control value is dithered using delta-sigma dithering.
13. A method, comprising:
converting, by a device comprising an electronic circuit, a time-varying voltage signal to a discrete-time signal;
determining, by the device, a quantizer statistic value based on the discrete-time signal; and
determining, by the device, a signal statistic value for the time-varying voltage signal as a function of the quantizer statistic value and a gain control value as a function of the quantizer statistic value.
14. The method of claim 13 , wherein the electronic circuit is a multi-bit quantizer circuit.
15. The method of claim 13 , wherein the quantizer statistic value represents an instantaneous amplitude value.
16. The method of claim 13 , further comprising determining, by the device, the quantizer statistic value as a function of the discrete-time signal and a clock signal value.
17. The method of claim 13 , further comprising determining, by the device, the signal statistic value and the gain control value as a function of the quantizer statistic value and a clock signal value.