Subsampling RF receiver architecture
First Claim
1. A subsampling receiver, comprising:
- a first bandpass filter coupled to receive a modulated signal, the modulated signal including at least one carrier signal at radio frequencies, modulated by a payload signal having frequencies significantly lower than the carrier signal and within a first bandwidth, the first bandpass filter passing frequencies within a frequency band at least as wide as the first bandwidth in a range including the at least one carrier signal;
a first sample and hold circuit, having an input coupled to the first bandpass filter, for sampling the modulated signal at a sampling frequency substantially lower than the frequency of the at least one carrier signal; and
a first analog to digital converter, coupled to the first sample and hold circuit, for digitizing the sampled modulated signal to produce a digital signal at a baseband frequency and corresponding to the payload signal.
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Accused Products
Abstract
A subsampling receiver (50, 50′, 50″) for converting an RF signal to baseband is disclosed. The subsampling receiver (50, 50′, 50″) may be implemented into a wireless communications device (40), such as a wireless telephone handset. In one disclosed embodiment, the receiver (50) includes a sample and hold circuit (80) that samples a bandpass filtered input modulated signal at the subsampling frequency (fs) that is well below the RF carrier frequency but twice the bandwidth (BW) of the payload; the sampled signal is digitized, and applied to two digital mixers (85I, 85Q) to produce in-phase and quadrature components (I,Q) of the payload. In another embodiment, the receiver (50′) includes two sample and hold circuits (96I, 96Q) to sample the filtered signal at different phases of the sampling frequency, to produce the in-phase and quadrature digital components. In a third embodiment, the receiver (50″) includes an analog mixer (116) to downconvert the RF input to an intermediate frequency, prior to digitization and digital mixing at quadrature phase.
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Citations
35 Claims
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1. A subsampling receiver, comprising:
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a first bandpass filter coupled to receive a modulated signal, the modulated signal including at least one carrier signal at radio frequencies, modulated by a payload signal having frequencies significantly lower than the carrier signal and within a first bandwidth, the first bandpass filter passing frequencies within a frequency band at least as wide as the first bandwidth in a range including the at least one carrier signal;
a first sample and hold circuit, having an input coupled to the first bandpass filter, for sampling the modulated signal at a sampling frequency substantially lower than the frequency of the at least one carrier signal; and
a first analog to digital converter, coupled to the first sample and hold circuit, for digitizing the sampled modulated signal to produce a digital signal at a baseband frequency and corresponding to the payload signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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17. A wireless communications unit, comprising:
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an antenna;
a speaker;
a digital signal processor, for performing digital signal processing on signals received at the antenna;
an audio interface, for communicating processed received signals from the digital signal processor to the speaker; and
a subsampling receiver, comprising;
a first bandpass filter coupled to receive a modulated signal from the antenna, the modulated signal including at least one carrier signal at radio frequencies, modulated by a payload signal having frequencies significantly lower than the carrier signal and within a first bandwidth, the first bandpass filter passing frequencies within a frequency band at least as wide as the first bandwidth in a range including the at least one carrier signal;
a first sample and hold circuit, having an input coupled to the first bandpass filter, for sampling the modulated signal at a sampling frequency substantially lower than the frequency of the at least one carrier signal; and
a first analog to digital converter, coupled to the first sample and hold circuit, for digitizing the sampled modulated signal to produce, at an output coupled to the digital signal processor, a digital signal at a baseband frequency and corresponding to the payload signal.
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25. A method of converting a received modulated signal to a baseband payload signal, the modulated signal including at least one carrier signal at radio frequencies, modulated by a payload signal having frequencies significantly lower than the carrier signal and within a first bandwidth:
- , the method comprising the steps of;
bandpass filtering the modulated signal, to pass frequencies within a frequency band at least as wide as the first bandwidth in a range including the at least one carrier signal;
sampling the modulated signal at a sampling frequency substantially lower than the frequency of the at least one carrier signal; and
digitizing the sampled modulated signal to produce a digital signal at a baseband frequency and corresponding to the payload signal.
- , the method comprising the steps of;
Specification