Patent ID: 7321754

Claim:
A radio-frequency signal frequency conversion device for generating intermediate signals intended to be processed in a correlation stage of a low power RF receiver of GPS type wherein the device is adapted to be mounted in a portable small sized object, the device including: a first pass-band filter for filtering radio-frequency signals picked up by an antenna of the receiver, said first filter is a passive selective filter of the SAW type that is sufficiently selective to eliminate image frequencies during a first frequency conversion from received radio-frequency signals; oscillating signal generating means for generating first and second high frequency signals, the frequency of the first signals is higher than the frequency of the second signals, wherein the oscillating signal generating means includes a reference oscillator comprising a quartz crystal; a first mixer unit for mixing filtered radio-frequency signals with the first high frequency signals in order to generate signals whose frequency is equal to the result of a subtraction of the frequency of the first signals from a carrier frequency of the radio-frequency signals; a second pass-band filter for filtering signals originating from the first mixer unit; a second mixer unit for mixing signals filtered by the second filter with the second high frequency signals in order to generate signals whose frequency is equal to the result of a subtraction of the frequency of the second signals from the frequency of the signals originating from the first mixer unit; and shaping means for signals provided by the second mixer unit for generating the intermediate signals; wherein the second filter is a not very selective active filter operable to remove a harmonic frequency because an attenuation slope of the second filter around a first frequency is not steep so that the active filter is capable of removing the harmonic frequency, and wherein the second filter is integrated in an RF/IF integrated circuit with the first mixer unit, the second mixer unit, the signal shaping means, and the oscillating signal generating means with the exception of a control signal filtering low-pass filter for a voltage controlled oscillator of a frequency synthesizer and the quartz crystal of the reference oscillator unit of the oscillating signal generating means.