US 4,023,112 AGranted

Broad band amplifier having negative feedback and a controllable amplification factor

AssigneeTelefonaktiebolaget L M Ericsson

InventorsBodo Kurt Adolf Duncker, Bo Soren Tage Eberstein

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Abstract

A broad band amplifier with negative feedback and controllable amplification factor for use in a carrier frequency system is described. The amplifier is preferably used as a control amplifier in the receiver of a basic group, for example, a basic 60-group of the system wherein the amplification of the amplifier is then controlled by a pilot receiver common for all the 60-groups. The amplifier includes an amplifier stage having constant amplification and which receives the pilot signal. A negative feedback path is connected via a first impedance converter from the output to the input of the amplifier stage. This path includes a capacitive voltage divider together with a second impedance converter and an RC-link. The capacitor values in the voltage divider are varied in dependence on a regulating voltage from the pilot receiver of the system, whereby the degree of negative feedback and thus the amplification of the amplifier can be controlled.

Claims9

Dependent claims

A broad band amplifier having negative feedback and a controllable amplification factor comprising:

an amplifier stage with constant amplification factor and having an input adapted to receive a signal to be amplified and an output;
a first impedance converter having a high impedance input and a low impedance output, the input being connected to the output of said amplifier stage for converting the high impedance output from said stage to a low impedance output;
a capacitive voltage divider including variable capacitor means and having a first input connected to the output of said first impedance converter and an output;
a second impedance converter having a high impedance input connected to the output of said capacitive voltage divider and a low impedance output;
and
connecting means for connecting the output of said second impedance converter to the input of said amplifier stage for controlling the negative feedback of the amplifier in dependence on the capacitance of the capacitor means in said capacitive voltage divider, whereby the amplification factor of the amplifier can be controlled.

3 more elements

Dependencies are inferred from the claim text.