Electronic devices for the automatic control of gain and roll-off in amplifiers

Claim 1

In an electronic circuit for the automatic control of gain and roll-off in amplifiers having input and output terminals and feedback therebetween especially wide-band amplifiers for use in the primary line of tele-distribution systems, the improvement wherein the feedback network includes a first pure ohmic resistance, the value of which is automatically variable within preestablished limits as a function of the level of a variable intensity current pilot signal, a first capacitor coupling one side of said first ohmic resistance to the amplifier output terminal, and a second capacitor coupling the other side of said first ohmic resistance to the amplifier input terminal, an inductance having one side coupled between said one side of said first ohmic resistance and said first capacitor for applying a variable intensity current pilot signal to said first ohmic resistance, a return path for said variable intensity current pilot signal coupled between said other side of said first ohmic resistance and said second capacitor to furnish a control current to said first ohmic resistance causing it to change its ohmic value to achieve control of gain and roll-off, a second negative temperature coefficicent ohmic resistance in series with an inductance in the feedback network and means provided to inject a pilot signal of lower frequency into said second ohmic resistance, said second ohmic resistance and said serially connected inductance being connected in parallel with said first ohmic resistance.