Increasing ADC dynamic range by time domain selective cancellation of predictable large PAPR signals
Increasing an analog to digital converter (ADC) dynamic range for a communications device. In the communications device, a reference threshold is established for a peak to average power ratio (PAPR) improvement factor for RF signals received by the communications device. A digital to analog converter (DAC) adjustment factor is established for a DAC to account for inaccuracies of a pre-cancellation DAC and fine tuning of an analog gain of received RF signals. A peak amplitude separation element, disposed within the communications device, evaluates an absolute value of a portion of a particular RF signal against the reference threshold. Upon the peak amplitude separation element determining that the portion is smaller than the reference threshold, the element assigns a zero value to a DAC signal current sample; otherwise, the element assigns a quantized value of the sample to the DAC signal current sample, used in adjusting a post-cancellation signal sample.
1. One or more non-transitory computer-readable storage mediums storing one or more sequences of instructions for increasing an analog to digital converter (ADC) dynamic range for a communications device, which when executed by one or more processors, cause:
in the communications device, establishing a reference threshold for a peak to average power ratio (PAPR) improvement factor for RF signals received by the communications device;
a peak amplitude separation element evaluating an absolute value of a portion of a particular RF signal against said reference threshold, wherein said peak amplitude separation element is disposed within said communications device;
upon the peak amplitude separation element determining that the portion is smaller than said reference threshold, the peak amplitude separation element assigning a zero value to a DAC signal current sample; and
upon the peak amplitude separation element determining that the portion is larger or equal to said reference threshold, the peak amplitude separation element assigning a quantized value of the sample to the DAC signal current sample.
2. The one or more non-transitory computer-readable storage mediums of claim 1 , wherein execution of the one or more sequences of instructions further cause:
in the communications device, establishing a digital to analog converter (DAC) adjustment factor of a digital to analog converter (DAC) to account for inaccuracies of a pre-cancellation DAC and fine tuning of an analog gain of the RF signals received by the communication device; and
the peak amplitude separation element adjusting a post-cancellation signal sample by scaling the DAC current sample according to said DAC adjustment factor.
3. The one or more non-transitory computer-readable storage mediums of claim 1 , wherein establishing the reference threshold is performed periodically or in accordance with a schedule.
4. The one or more non-transitory computer-readable storage mediums of claim 1 , wherein establishing the DAC adjustment factor is performed periodically or in accordance with a schedule.
5. The one or more non-transitory computer-readable storage mediums of claim 1 , wherein current sources in the digital to analog converter (DAC) are turned off while a zero value is assigned to the DAC signal current sample, except within a few samples before a non-zero value is about to be assigned to the DAC.
6. The one or more non-transitory computer-readable storage mediums of claim 1 , wherein the digital to analog converter (DAC) is a three-state DAC.
7. The one or more non-transitory computer-readable storage mediums of claim 1 , wherein said pre-cancellation DAC is a 2 bit pre-cancellation DAC or a 3 bit pre-cancellation DAC.
8. The one or more non-transitory computer-readable storage mediums of claim 1 , wherein said pre-cancellation DAC employs a current diversion switch to divert current between two separate outputs of the pre-cancellation DAC.
9. The one or more non-transitory computer-readable storage mediums of claim 1 , wherein current sources in the pre-cancellation DAC are turned off while a zero value is provided to the pre-cancellation DAC.
10. The one or more non-transitory computer-readable storage mediums of claim 1 , wherein current of each current source of the pre-cancellation DAC may be diverted by a current diversion switch to any one member of a set consisting of a positive output, a negative output, and a current sink.
11. An apparatus for increasing an analog to digital converter (ADC) dynamic range for a communications device, comprising:
a first hardware or software component, in the communications device, that establishes a reference threshold for a peak to average power ratio (PAPR) improvement factor for RF signals received by the communications device; and
a peak amplitude separation element that evaluates an absolute value of a portion of a particular RF signal against said reference threshold, wherein said peak amplitude separation element is disposed within said communications device, wherein the peak amplitude separation element is configured to assign a zero value to a DAC signal current sample upon determining that the portion is smaller than said reference threshold, and wherein the peak amplitude separation element is configured to assign a quantized value of the sample to the DAC signal current sample upon determining that the portion is larger or equal to said reference threshold.
12. The apparatus of claim 11 , further comprising:
in the communications device, a second hardware or software component that establishes a digital to analog converter (DAC) adjustment factor of a digital to analog converter (DAC) to account for inaccuracies of a pre-cancellation DAC and fine tuning of an analog gain of the RF signals received by the communication device, and wherein the peak amplitude separation element adjusts a post-cancellation signal sample by scaling the DAC current sample according to said DAC adjustment factor.
13. The apparatus of claim 11 , wherein establishing the reference threshold is performed periodically or in accordance with a schedule.
14. The apparatus of claim 11 , wherein establishing the DAC adjustment factor is performed periodically or in accordance with a schedule.
15. The apparatus of claim 11 , wherein current sources in the digital to analog converter (DAC) are turned off while a zero value is assigned to the DAC signal current sample, except within a few samples before a non-zero value is about to be assigned to the DAC.
16. The apparatus of claim 11 , wherein the digital to analog converter (DAC) is a three-state DAC.
17. The apparatus of claim 11 , wherein said pre-cancellation DAC is a 2 bit pre-cancellation DAC or a 3 bit pre-cancellation DAC.
18. The apparatus of claim 11 , wherein said pre-cancellation DAC employs a current diversion switch to divert current between two separate outputs of the pre-cancellation DAC.
19. The apparatus of claim 11 , wherein current sources in the pre-cancellation DAC are turned off while a zero value is provided to the pre-cancellation DAC.
20. The apparatus of claim 11 , wherein current of each current source of the pre-cancellation DAC may be diverted by a current diversion switch to any one member of a set consisting of a positive output, a negative output, and a current sink.
21. A method for increasing an analog to digital converter (ADC) dynamic range for a communications device, comprising:
in the communications device, establishing a reference threshold for a peak to average power ratio (PAPR) improvement factor for RF signals received by the communications device;
a peak amplitude separation element evaluating an absolute value of a portion of a particular RF signal against said reference threshold, wherein said peak amplitude separation element is disposed within said communications device;
upon the peak amplitude separation element determining that the portion is smaller than said reference threshold, the peak amplitude separation element assigning a zero value to a DAC signal current sample; and
upon the peak amplitude separation element determining that the portion is larger or equal to said reference threshold, the peak amplitude separation element assigning a quantized value of the sample to the DAC signal current sample.