LOW NOISE FREQUENCY CONVERTER WITH HIGH IMAGE FREQUENCY REJECTION

摘要

P The present invention relates to a frequency converter, intended to deliver an output signal having a radio frequency FR, equal to the difference between the frequency FLO of a signal OS coming from an oscillator VCO and the frequency FI of a IS input signal. According to the invention, such a frequency converter includes:. two quadratic modules QM1 and QM2 to separate the signal 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 to multiply two-by-two the components thus obtained,. COMB combination means for recombining the output signals RS1 and RS2 of the mixers MX1 and MX2. The invention allows the frequency converter to carry out, internally, a good rejection of the image frequency, while offering good performance in noise and gain and linearity improved compared to known converters. Application: Frequency offset before transmission in a radiotelephone. /P