Patent ID: 7587010
Filing Date: 2009-09-08
Classification: H04B

Abstract:
1. A quadrature-modulated signal receiver circuit, comprising: a quadrature demodulator for quadrature-demodulating a received signal; a complex filter circuit comprising first and second filter circuits receiving first and second signals, respectively, which are in a quadrature-phase relationship with each other, wherein: each of the first and second filter circuits includes at least one variable element whose element value is variable; the complex filter circuit comprises an element value control section for changing the element value of a variable element in the first filter circuit and the element value of a corresponding variable element in the second filter circuit so that absolute values of the element values of the variable elements increase/decrease in opposite directions; a signal switch for selectively inputting to the receiver circuit one of an actual signal and a pseudo-image signal imitating an image signal contained in the actual signal; an amplitude detection section for detecting an amplitude of a signal having passed through the complex filter circuit; and a filter control section for controlling the element value control section in the complex filter circuit based on the amplitude detected by the amplitude detection section, wherein the filter control section controls the element value control section with the pseudo-image signal being input to the receiver circuit via the signal switch so as to decrease the amplitude detected by the amplitude detection section.