Error-feedback digital-to-analog converter (DAC)
AssigneeQUALCOMM Incorporated
InventorsMohammadhossein Naderi Alizadeh, Shahin Mehdizad Taleie, Dongwon Seo
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Abstract
In one embodiment, a method for converting an input digital signal into an analog signal is provided. The method comprises modulating the input digital signal into a modulated digital signal, and converting the modulated digital signal into the analog signal using a digital-to-analog converter (DAC). The modulation shapes quantization noise of the DAC to place a notch at a frequency within an out-of-bound frequency band to reduce the quantization noise within the out-of-bound frequency band.
Claims31
A circuit, comprising:
- a transmit mode controller configured to adjust a sampling frequency of an input digital signal;
- an error-feedback modulator configured to receive the input digital signal, and to modulate the digital input signal into a modulated digital signal;
- and
- a digital-to-analog converter (DAC) configured to convert the modulated digital signal into an analog signal;
- wherein the error-feedback modulator is configured to modulate the input digital signal to shape quantization noise of the DAC to produce a notch, and the transmit mode controller is configured to adjust the sampling frequency of the input signal to place the notch at a frequency within an out-of-bound frequency band to reduce the quantization noise within the out-of-bound frequency band.
The circuit of 1, wherein the error-feedback modulator comprises:
- an adder;
- and
- a feedback filter;
- wherein the adder is configured to add an output signal of the feedback filter to the input digital signal, and M most significant bits (MSBs) of an output signal of the adder provide the modulated digital signal of the modulator;
- wherein the feedback filter is configured to filter N least significant bits (LSBs) of the output signal of the adder to generate the output signal of the feedback filter.
A method for converting an input digital signal into an analog signal, comprising:
- adjusting a sampling frequency of the input digital signal;
- modulating the input digital signal into a modulated digital signal;
- and
- converting the modulated digital signal into the analog signal using a digital-to-analog converter (DAC);
- wherein the modulating shapes quantization noise of the DAC to produce a notch, and adjusting the sampling frequency of the input digital signal comprises adjusting the sampling frequency of the input digital signal to place the notch at a frequency within an out-of-bound frequency band to reduce the quantization noise within the out-of-bound frequency band.
An apparatus for converting an input digital signal into an analog signal, comprising:
- means for adjusting a sampling frequency of the input digital signal;
- means for modulating the input digital signal into a modulated digital signal;
- and
- means for converting the modulated digital signal into the analog signal;
- wherein the modulating shapes quantization noise of the DAC to produce a notch, and the means for adjusting the sampling frequency of the input digital signal comprises means for adjusting the sampling frequency of the input digital signal to place the notch at a frequency within an out-of-bound frequency band to reduce the quantization noise within the out-of-bound frequency band.
Dependencies are inferred from the claim text.