Wide band zero if quadrature demodulator using a intermediate frequency and a single local oscillator
First Claim
1. A low power zero-IF selective call receiver, comprising:
- a local oscillator that generates an injection signal at a first frequency (fLO);
a first mixer coupled to the local oscillator for converting a received carrier signal of a second frequency (fC) to an intermediate signal of a third frequency (fIF) in response to the injection signal at the first frequency (fLO), where the third frequency (fIF) associated with the intermediate signal is one of a sum or a difference of the first (fLO) and second (fC) frequencies;
a digital phase shifter/divider coupled to the local oscillator and to the first mixer, the digital phase shifter/divider generating a pair of quadrature phase related injection signals at the third frequency (fIF) which is the first frequency (fLO) divided by an integer greater than 1;
a pair of second mixers coupled to the digital phase shifter/divider and the first mixer, the pair of second mixers converting an in phase component of the intermediate signal to an in phase baseband signal and a quadrature component of the intermediate signal to a quadrature baseband signal in response to an in phase and quadrature component of the pair of quadrature phase related injection signals, respectively.
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Accused Products
Abstract
A low power zero-IF selective call receiver has a local oscillator (106) that generates an injection signal for a first mixer (104) and a pair of quadrature phase related injection signals (122, 124) for a pair of second mixers (112, 114). The first mixer converts the received carrier signal (102) to an intermediate signal (108). A digital phase shifter/divider (116) coupled to the local oscillator (106) generates the pair of quadrature phase related injection signals (122, 124) at the frequency of the intermediate signal (108) which also equals the frequency of the local oscillator (106) divided by an integer greater then 1. The pair of second mixers (112, 114) coupled to the digital phase shifter/divider (116) converts the in and quadrature phase components (122, 124) of the intermediate signal (108) to respective in and quadrature phase baseband signals (126, 128).
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Citations
29 Claims
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1. A low power zero-IF selective call receiver, comprising:
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a local oscillator that generates an injection signal at a first frequency (fLO); a first mixer coupled to the local oscillator for converting a received carrier signal of a second frequency (fC) to an intermediate signal of a third frequency (fIF) in response to the injection signal at the first frequency (fLO), where the third frequency (fIF) associated with the intermediate signal is one of a sum or a difference of the first (fLO) and second (fC) frequencies; a digital phase shifter/divider coupled to the local oscillator and to the first mixer, the digital phase shifter/divider generating a pair of quadrature phase related injection signals at the third frequency (fIF) which is the first frequency (fLO) divided by an integer greater than 1; a pair of second mixers coupled to the digital phase shifter/divider and the first mixer, the pair of second mixers converting an in phase component of the intermediate signal to an in phase baseband signal and a quadrature component of the intermediate signal to a quadrature baseband signal in response to an in phase and quadrature component of the pair of quadrature phase related injection signals, respectively. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A low power zero-IF selective call receiver, comprising:
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a local oscillator that generates an injection signal at a first frequency for converting a received carrier signal at a second frequency to an intermediate signal at a third frequency; a digital phase shifter/divider coupled to the local oscillator, the digital phase shifter/divider generating at the third frequency, an in phase injection signal and a quadrature phase injection signal; a first mixer coupled to the local oscillator and the digital phase shifter/divider, the first mixer converting the received carrier signal to an intermediate signal at the third frequency in response to the injection signal at the first frequency, the third frequency being one of a sum or a difference of the first and second frequencies and further being equal to the first frequency divided by an integer greater than 1; a second mixer coupled to the first mixer and the digital phase shifter/divider, the second mixer converting an in phase component of the intermediate signal to an in phase baseband signal in response to the in phase injection signal; and a third mixer coupled to the first mixer and the digital phase shifter/divider, the third mixer converting a quadrature component of the intermediate signal to a quadrature baseband signal in response to the quadrature phase injection signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A low power zero-IF selective call receiver, comprising:
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a first mixer receiving a carrier signal at a second frequency, and in response to a local oscillator injection signal at a first frequency, producing a walking intermediate frequency signal at a third frequency; a direct conversion quadrature demodulator receiving the walking intermediate frequency signal from the first mixer and producing at least two output signals representing the real and imaginary components of modulated information contained in the carrier signal; a local oscillator operating to provide the first local oscillator injection signal to the first mixer at the first frequency, and a second local oscillator injection signal to the direct conversion quadrature demodulator at the third frequency which is equal to the first frequency divided by an integer N greater than 1 and further equal to one of a sum or a difference of the first and second frequencies. - View Dependent Claims (27, 28, 29)
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Specification