US 4,019,160 A · Signal attenuator circuit for TV tuner

Abstract

In a tuner for a television receiver, an attenuator circuit coupling a signal input to a signal output network includes a series connected controllable impedance and amplifier stage connected to a source of AGC potential whereby increased signal strength causes an increased AGC potential which reduces current flow through and increases the impedance of the controllable impedance while reducing the gain, and consequently the noise, of the amplifier stage coupled to the signal output network. In another aspect of the invention, a second attenuator circuit includes a second controllable impedance series coupling a signal input to the attenuator circuit and a third controllable impedance coupling the junction of the first and second controllable impedances to circuit ground for effecting an additional increased attenuation of a received signal.

Claims7

Dependent claims

TV tuner attenuator circuit comprising:

signal input and output network means;
signal amplifier stage coupled to a bias network and to said signal output network means;
controllable impedance means in the form of a PIN diode AC coupled to said signal input network means and DC coupled to said signal amplifier stage and to a potential reference level;
and
control signal means DC coupled to said controllable impedance means for altering current flow through said signal amplifier stage and controllable impedance means in a direction opposite to the direction of change of said applied signal whereby gain reduction of said signal amplifier stage and increased impedance of said controllable impedance means are combined to non-linearly attenuate an increase in applied signals.

2 more elements

Dependencies are inferred from the claim text.

Signal attenuator circuit for TV tuner

Life of this patent

Signal attenuator circuit for TV tuner

Life of this patent

Abstract

Claims7