Mixer device with image frequency rejection
First Claim
Patent Images
1. Mixer device with image frequency rejection, comprising:
- mixing means for forming a first signal by mixing an input radio signal with a first wave of frequency fO delivered by a local oscillator and a second signal by mixing the input radio signal with a second wave of frequency fO delivered by the local oscillator and having a phase lag of 90°
with respect to said first wave;
means of algebraic summation of third and fourth mutually phase-shifted signals obtained from said first and second signals, in order to produce an output signal possessing, at an intermediate frequency fI, a phase representative of a phase possessed by the input radio signal at a communication frequency fC of the form fO -fI or fO +fI, with rejection of the phase possessed by the input radio signal at an image frequency 2fO -fC ;
phase-shifter means producing said third signal by filtering an algebraic sum of the first and second signals with a transfer function A(f); and
means for producing said fourth signal by applying to one of said first and second signals a transfer function B(f) such that, at the intermediate frequency fI, the ratio A(fI)/B(fI) has modulus 1/√
2 and argument ±
45°
or ±
135°
.
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Abstract
The device forms first and second signals by mixing the input radio signal with two respective quadrature waves of frequency fO. An algebraic sum of these two signals is phase-shifted by ±45° or ±135° at an intermediate frequency fI. An output signal is formed by an algebraic sum between the phase-shifted signal and the first or second signal, in such a way that, at the intermediate frequency fI, the output signal has a phase representative of that possessed by the input radio signal at a communication frequency fC of the form fO -fI or fO +fI, with rejection of the phase of the input radio signal at the image frequency 2fO -fC.
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Citations
15 Claims
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1. Mixer device with image frequency rejection, comprising:
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mixing means for forming a first signal by mixing an input radio signal with a first wave of frequency fO delivered by a local oscillator and a second signal by mixing the input radio signal with a second wave of frequency fO delivered by the local oscillator and having a phase lag of 90°
with respect to said first wave;means of algebraic summation of third and fourth mutually phase-shifted signals obtained from said first and second signals, in order to produce an output signal possessing, at an intermediate frequency fI, a phase representative of a phase possessed by the input radio signal at a communication frequency fC of the form fO -fI or fO +fI, with rejection of the phase possessed by the input radio signal at an image frequency 2fO -fC ; phase-shifter means producing said third signal by filtering an algebraic sum of the first and second signals with a transfer function A(f); and means for producing said fourth signal by applying to one of said first and second signals a transfer function B(f) such that, at the intermediate frequency fI, the ratio A(fI)/B(fI) has modulus 1/√
2 and argument ±
45°
or ±
135°
. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification