Wireless receiver circuit and method
A circuit and a method are used estimate quality of the output of a wireless receiver. This quality measure is used to control the supply voltage and thereby provide power savings.
1. A wireless receiver circuit comprising:
a wireless receiver unit, coupled to receive a drive voltage, and configured to receive a plurality of digital samples and to output a set of encoded digital output bits;
a forward error correction decoder coupled to receive the set of encoded digital output bits from the wireless receiver unit;
a forward error correction encoder coupled to the forward error correction decoder and configured to re-encode output of the forward error correction decoder;
a Hamming distance unit configured to output a measured Hamming distance between the set of encoded digital output bits from the wireless receiver unit and the re-encoded output of the forward error correction encoder;
a voltage control unit configured to adjust the drive voltage to the wireless receiver circuit to a minimum voltage based on a difference between the measured Hamming distance and a target Hamming distance; and
wherein the minimum voltage does not turn off the wireless receiver circuit.
2. A circuit as claimed in claim 1 , further comprising a quantizer between the voltage control unit and a voltage regulator.
3. A circuit as claimed in claim 1 , wherein the receiver receives a forward error correction encoded bit stream.
4. A battery operated device comprising a wireless receiver circuit as claimed in claim 1 .
5. A battery operated device as claimed in claim 4 comprising a hearing aid.
6. The circuit of claim 1 , wherein the minimum voltage corresponds to a voltage where the receiver circuit begins to introduce timing errors.
7. The circuit of claim 1 , wherein the minimum voltage is less than a guardband voltage of the wireless receiver circuit.
8. The circuit of claim 1 :
wherein the receiver circuit includes a timing-error-resilient (TER) circuit and a non-timing-error-resilient (NTER) circuit;
wherein the minimum voltage is less than a guardband voltage for the timing-error-resilient (TER) circuit; and
wherein the minimum voltage is greater than or equal to the guardband voltage for the non-timing-error-resilient (NTER) circuit.
9. A method of controlling a drive voltage to a wireless receiver unit, comprising:
implementing a voltage overscaling function for the wireless receiver unit;
performing a forward error correction decoding step on digital output bits from the wireless receiver unit;
performing a forward error correction encoding step for re-encoding digital output bits from the forward error correction decoding step;
determining, from the received digital output bits from the wireless receiver unit and from the re-encoded digital output bits from the forward error correction encoding step, a measure of a Hamming distance;
deriving a control output from a difference between the measured Hamming distance and a target Hamming distance; and
adjusting a drive voltage to the wireless receiver unit to a minimum voltage, in dependence on the control output;
wherein the minimum voltage does not turn off the wireless receiver circuit.
10. A method as claimed in claim 9 , further comprising quantizing the control output.
11. A method as claimed in claim 9 performed in a battery operated device.
12. A method as claimed in claim 11 performed in a hearing aid.