Telecommunications – Receiver or analog modulated signal frequency converter – Noise or interference elimination
Patent
1997-03-11
1999-06-29
Vo, Nguyen
Telecommunications
Receiver or analog modulated signal frequency converter
Noise or interference elimination
455317, 455318, 455324, 4552341, H04B 126
Patent
active
059181672
ABSTRACT:
A quadrature downconversion stage in a radio frequency receiver compensates for leakage from the quadrature local oscillator to the input of the stage by deriving first and second feedback signals from the quadrature local oscillator. The first feedback signal is 180.degree. out of phase with the in-phase component of the signal supplied to the input of the stage and the second feedback signal is 180.degree. out of phase with the quadrature component of the signal supplied to the input of the stage. The invention reduces or cancels a d.c. offset that can appear at the output of the stage. Another advantage is the reduction of re-radiated signals resulting from the local oscillator leakage. The invention is particularly applicable to direct converters.
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Nisbet John Jackson
Tiller Samuel Alfred
Nguyen Duc
Northern Telecom Limited
Vo Nguyen
LandOfFree
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