Abstract: An embodiment of a variable-gain mixer for down-converting a modulated input signal into a modulated output signal in a wireless receiver is proposed. The mixer includes means for selecting a mixer gain according to a power level of the input signal, amplifying means for amplifying the input signal into a modulated intermediate current (IRF+,IRF?) in response to a control signal indicative of the selected mixer gain, the intermediate current having an intermediate component, consisting of a direct current, varying according to the selected mixer gain, means for generating the output signal from the intermediate current, the output signal having an output component, consisting of a direct current or voltage, depending on the intermediate component; in an embodiment, the mixer further includes means for setting a compensation current in response to the control signal for compensating the variation of the intermediate component, and means for adding the compensation current to the intermediate current.

Abstract: An embodiment of a variable-gain mixer for down-converting a modulated input signal into a modulated output signal in a wireless receiver is proposed. The mixer includes means for selecting a mixer gain according to a power level of the input signal, amplifying means for amplifying the input signal into a modulated intermediate current (IRF+,IRF?) in response to a control signal indicative of the selected mixer gain, the intermediate current having an intermediate component, consisting of a direct current, varying according to the selected mixer gain, means for generating the output signal from the intermediate current, the output signal having an output component, consisting of a direct current or voltage, depending on the intermediate component; in an embodiment, the mixer further includes means for setting a compensation current in response to the control signal for compensating the variation of the intermediate component, and means for adding the compensation current to the intermediate current.

Abstract: The invention relates to a frequency converter designed for supplying an output signal having a radio frequency FR equal to the difference between the frequency FLO of a signal OS originating from an oscillator VCO and the frequency FI of an input signal IS. The frequency converter has two quadratic modules QM1 and QM2 for separating the signal originating from the-oscillator OS and the input signal IS into two components (LO1, LO2) and (FI1, FI2) in phase quadrature, two mixers MX1, and MX2 for multiplying the components thus obtained two-by-two, and combination means COMB for recombining the output signals RS1 and RS2 of the mixers MX1 and MX2. The frequency converter operates internally a good rejection of the image frequency while providing a good performance as regards noise and gain and an improved linearity as compared with known converters. Thus, frequency shifting before transmission in a wireless telephone may be accomplished.

Abstract: The invention relates to a frequency converter designed for supplying an output signal having a radio frequency FR equal to the difference between the frequency FLO of a signal OS originating from an oscillator VCO and the frequency FI of an input signal IS. According to the invention, such a frequency converter comprises: two quadratic modules QM1 and QM2 for separating the signal originating from the oscillator OS and the input signal IS into two components (LO1, LO2) and (FI1, FI2) in phase quadrature, two mixers MX1, and MX2 for multiplying the components thus obtained two-by-two, combination means COMB for recombining the output signals RS1 and RS2 of the mixers MX1 and MX2. The invention enables the frequency converter to operate internally a good rejection of the image frequency while providing a good performance as regards noise and gain and an improved linearity as compared with known converters.