Patent ID: 6081151
Filing Date: 2000-06-27
Classification: H03H

Abstract:
A variable attenuation circuit connected between a signal input and an output, characterized in that it includes two resistors mounted in series between the signal input and the output of the circuit, a first diode mounted in parallel with the said resistors and connected between the signal input and the output of the circuit, and a second diode connected between a midpoint node between the two resistors and earth,and in that a biasing device consist of a differential pair of transistors, a first branch of which is connected to the cathode of the first diode and a second branch of which is connected to the cathode of the second diode, the anode of the said first diode being connected to a continuous supply terminal, the differential pair of transistors being supplied by a variable current source in order to set the characteristic impedance of the attenuator circuit and receiving, on a first input, a reference voltage intended to position a dynamic range of a control voltage of the circuit and, on a second input, the control voltage by means of a first bridge of resistors, which first resistor bridge is intended to set the size of the dynamic range of the control voltage.