Patent ID: 8503963

Claim:
An integrated circuit for a radio receiver, the integrated circuit comprising: a radio-frequency amplifier and a radio-frequency filter, the radio-frequency amplifier being arranged to receive radio-frequency signals from an antenna, the radio-frequency filter being connected to the radio-frequency amplifier output, the output of the radio-frequency filter being provided to a processing stage of the receiver, the radio-frequency amplifier comprising an amplifying stage controlled by a radio-frequency input signal and a signal fed back from the radio-frequency filter, the radio-frequency amplifier input impedance being substantially matched to the antenna impedance at a frequency band of interest, the signal fed back from the radio-frequency filter providing attenuation of signals outside the frequency band of interest at the radio-frequency amplifier input, the radio-frequency filter comprising at least a first filter component, the first filter component comprising: a first input and a second input for receiving the radio-frequency amplifier output; a first switch arranged to selectively connect the first input to a first impedance; a second switch arranged to selectively connect the first input to a second impedance; a third switch arranged to selectively connect the second input to the first impedance; and a fourth switch arranged to selectively connect the second input to the second impedance; the first and fourth switches being controlled by a first oscillator signal and the second and third switches being controlled by a second oscillator signal that is 180° out of phase with the first oscillator signal.