METHOD AND CIRCUIT FOR A FAST REDUCTION IN VOLTAGE OF A DC COMPONENT AND LOW-FREQUENCY COMPONENTS AT A MIXING CIRCUIT OUTPUT IN A RECEIVER OF A UHF TRANSCEIVER

摘要

A difference between an output current signal (mos) of the mixing circuit (MC) and a current from a controlled current source (CCS) is conducted to an input of an operational amplifier (A). A control voltage (cv) for said current source is a voltage at the output of the operational amplifier (A) being filtered by a low-pass filter, whose limiting frequency equals a low frequency limit of the modulation signal in the received signal (rs). The method is speeded up in that the limiting frequency of the low-pass filter is increased by two to three orders of magnitude at the beginning and is gradually lowered to said value. A rather short time duration of the transient process is achieved so that the working point with a low voltage of the DC component and low-frequency components is set at least five times faster than so far.