Receiver with sigma-delta analog-to-digital converter for sampling a received signal
First Claim
1. A receiver for demodulating an RF signal comprising:
- a front end stage configured to receive and downconvert said RF signal to an intermediate (IF) signal, said IF signal having a center frequency and a two-sided bandwidth;
a sigma-delta analog-to-digital converter coupled to said front end stage, said Σ
Δ
ADC configured to receive and sample said IF signal to provide IF samples, said Σ
Δ
ADC being clocked at a sampling frequency; and
a digital signal processor coupled to said Σ
Δ
ADC, said digital signal processor configured to receive and demodulate said IF samples in accordance with a modulation format used to produce said RF signal.
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Abstract
A receiver comprising a sigma-delta analog-to-digital converter (ΣΔ ADC) can be utilized in one of four configurations, as a subsampling bandpass receiver, a subsampling baseband receiver, a Nyquist sampling bandpass receiver, or a Nyquist sampling baseband receiver. For subsampling ΣΔ receivers, the sampling frequency is less than twice the center frequency of the input signal into the ΣΔ ADC. For Nyquist sampling ΣΔ receivers, the sampling frequency is at least twice the highest frequency of the input signal into the ΣΔ ADC. For baseband ΣΔ receivers, the center frequency of the output signal from the ΣΔ ADC is approximately zero or DC. For bandpass ΣΔ receivers, the center frequency of the output signal from the ΣΔ ADC is greater than zero. The sampling frequency can be selected based on the bandwidth of the input signal to simplify the design of the digital circuits used to process the output samples from the ΣΔ ADC. Furthermore, the center frequency of the input signal can be selected based on the sampling frequency and the bandwidth of the input signal. The ΣΔ ADC within the receiver provides many benefits.
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Citations
38 Claims
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1. A receiver for demodulating an RF signal comprising:
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a front end stage configured to receive and downconvert said RF signal to an intermediate (IF) signal, said IF signal having a center frequency and a two-sided bandwidth; a sigma-delta analog-to-digital converter coupled to said front end stage, said Σ
Δ
ADC configured to receive and sample said IF signal to provide IF samples, said Σ
Δ
ADC being clocked at a sampling frequency; anda digital signal processor coupled to said Σ
Δ
ADC, said digital signal processor configured to receive and demodulate said IF samples in accordance with a modulation format used to produce said RF signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A receiver for demodulating an RF signal comprising:
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a front end stage configured to receive and downconvert said RF signal to an intermediate (IF) signal; a quadrature demodulator coupled to said front end stage, said quadrature demodulator configured to receive and downconvert said IF signal into baseband I and Q signals; and two Σ
Δ
ADCs coupled to said quadrature demodulator, one Σ
Δ
ADC configured to receive said baseband I signal and one Σ
Δ
ADC configured to receive said baseband Q signal, said Σ
Δ
ADCs independently sampling said baseband I and Q signals to produce baseband samples, said Σ
Δ
ADC being clocked at a sampling frequency. - View Dependent Claims (34, 35, 36, 37, 38)
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Specification