METHOD AND CIRCUIT FOR NOISE REDUCTION

摘要

The present invention relates to a method that comprises, when converting signals using an analog multiplier into a large signal mode, turning one or both inputs of said multiplier into a current limitation or cut-out mode in relation to a reference voltage. This method is used for converting the signal and the noise when generating a reference voltage front. The transition to the given mode is made by selecting the reference voltage amplitude and/or supplying the reference voltage to the signal input of the analog multiplier, wherein said voltage is supplied to said signal input through a connection capacitor (13) or a buffer cascade (14) which are connected either to balancing capacitors (11, 15) or to the central point of an induction coil (8). In order to improve the noise reduction efficiency, the analog multiplier operates in a mode symmetrical to that of the reference and/or signal inputs. The noise-reducing method and circuit of the present invention may be used to decrease noise levels and the sensitivity threshold in receivers, to reduce the radiating noise of amplitude-modulated (AM) or frequency-modulated (FM) signal transmitters, to reduce the power or antenna size of transmitters and to obtain a broader spectrum for a good reception of AM and FM signals.