Receiver with reduced wake-up time
An auxiliary reduced power analog-to-digital converter (ADC) is provided for use during sleep periods of a receiver. The auxiliary ADC has a reduced dynamic range but sufficient accuracy to allow demodulation of signaling information contained in an input signal and to update control parameters used for synchronization and channel estimation. As such, a main higher power, higher dynamic range ADC can be turned off during sleep periods, reducing receiver power consumption. The main ADC is turned on at the end of a sleep period, and the receiver can be ready for receiving data immediately using the main ADC because the control parameters are maintained up to date during the sleep period using the auxiliary ADC.
1. A receiver, comprising:
a first analog-to-digital converter (ADC) configured to receive an input signal and to produce a first ADC signal;
a second ADC configured to receive the input signal and to produce a second ADC signal;
a receiver processing chain, wherein the receiver processing chain receives the first ADC signal or the second ADC signal in response to sleep mode information; and
a controller configured to receive the sleep mode information, wherein the controller turns on the first ADC and turns off the second ADC when the sleep mode information includes a sleep mode end instruction, and turns on the second ADC and turns of the first ADC when the sleep mode information includes a sleep mode begin instruction.
2. The receiver of claim 1 , wherein the second ADC has a lower dynamic range than the first ADC.
3. The receiver of claim 1 , wherein the first ADC signal includes a larger number of bits than the second ADC signal.
4. The receiver of claim 1 , wherein the receiver processing chain generates and updates control parameters retrieved from the input signal for maintaining synchronization with a transmitter and/or for channel estimation.
5. The receiver of claim 4 , wherein the receiver processing chain comprises:
a time domain processing module configured to receive and process the first ADC signal or the second ADC signal by applying at least one of a time offset correction, a carrier frequency offset correction, or automatic gain control (AGC) to produce a modified signal;
a Fast Fourier Transform (FFT) module configured to receive the modified signal and to produce a transformed signal which is a discrete Fourier transform of the modified signal; and
a frequency domain processing module configured to receive the transformed signal and to estimate at least one of a time offset between the receiver and the transmitter of the input signal, a carrier frequency offset between the receiver and the transmitter, a channel estimate of a channel between the receiver and the transmitter, or a trigger position of the FFT module.
6. The receiver of claim 1 , wherein the second ADC signal includes a representation of signaling information only.
7. The receiver of claim 1 , further comprising a multiplexer configured to receive the first ADC signal or the second ADC signal and to output one of the first ADC signal or the second ADC signal to the receiver processing chain,
wherein the multiplexer is configured to output the first ADC signal to the receiver processing chain when the sleep mode information includes a sleep mode end instruction, and to output the second ADC signal to the receiver processing chain when the sleep mode information includes a sleep mode begin instruction.
8. The receiver of claim 1 , wherein the receiver processing chain generates, from the second ADC signal, control parameters used by the receiver to receive data when the first ADC is turned on.
9. A receiver, comprising:
a first receiver processing chain, including a first analog-to-digital converter (ADC);
a second receiver processing chain, including a second ADC, wherein the second ADC has a lower dynamic range than the first ADC; and
a controller configured to receive sleep mode information, wherein the controller turns on the first receiver processing chain and turns off the second receiver processing chain when the sleep mode information includes a sleep mode end instruction, and turns on the second receiver processing chain and turns off the first receiver processing chain when the sleep mode information includes a sleep mode begin instruction.
10. The receiver of claim 9 , wherein the first ADC produces a first ADC signal, the second ADC produces a second ADC signal, and first ADC signal includes a larger number of bits than the second ADC signal.
11. The receiver of claim 9 , wherein the first receiver processing chain is configured to operate during an awake mode of the receiver, and the second receiver processing chain is configured to operate during a sleep mode of the receiver.
12. The receiver of claim 9 , wherein the second receiver processing chain implements a reduced number of functions implemented by the first receiver processing chain.
13. The receiver of claim 9 , wherein the second receiver processing chain retrieves signaling information from an input signal when turned on by the controller.
14. The receiver of claim 9 , wherein the first receiver processing chain and the second receiver processing chain share a time domain state memory or a frequency domain state memory.
15. A receiver, comprising:
an analog-to-digital converter (ADC) configured to receive an input signal and to produce a first ADC signal;
a refinement circuit, coupled to the ADC, configured to receive the first ADC signal and to generate a second ADC signal, wherein the second ADC signal includes a larger number of bits than the first ADC signal; and
a receiver processing chain to receive the first ADC signal or the second ADC signal.
16. The receiver of claim 15 , wherein the receiver processing chain receives the first ADC signal or the second ADC signal in response to a control signal.
17. The receiver of claim 16 , further comprising:
a controller configured to receive sleep mode information of the receiver and to generate the control signal in response to the sleep mode information.
18. The receiver of claim 17 , wherein the sleep mode information comprises one of a sleep mode start trigger or a sleep mode end trigger.
19. The receiver of claim 18 , wherein when the sleep mode information includes the sleep mode start trigger, the controller is further configured to:
determine a sleep mode start time; and
turn on the ADC and turn off the refinement circuit.
20. The receiver of claim 18 , wherein when the sleep mode information includes the sleep mode end trigger, the controller is further configured to:
determine a sleep mode end time; and
turn on the ADC and turn on the refinement circuit.