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US 4,066,976 AGranted
Amplifier with variable gain
AssigneeLicentia Patent-Verwaltungs-G.m.b.H.
InventorsGerhard Dickopp, Ernst Schroder
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AssigneeLicentia Patent-Verwaltungs-G.m.b.H.
InventorsGerhard Dickopp, Ernst Schroder
Estimating the term…
An amplifier circuit having a variable transmission factor and an effective transmission frequency band delimited by a lower limit frequency is arranged to enable the value of the lower limit frequency to be varied as a function of a control voltage, by including in the circuit an amplifier member and circuit components defining a feedback path connected between the output of the amplifier and an input thereof which is inverting with respect to the output signals of the amplifier, the components defining the feedback path including an electronically voltage-controllable resistor having a control voltage input and a first frequency dependent impedance connected in parallel with the resistor, and the circuit further including a second frequency dependent impedance connected between the inverting input of the amplifier and a point at the circuit reference potential, and a line for supplying the control voltage to the control voltage input of the controllable resistor.
In an amplifier circuit arranged to be connected in a useful signal path and having a variable transmission factor and an effective transmission frequency band delimited by a lower limit frequency which can be varied as a function of a control voltage, the circuit including an amplifier member and circuit components defining a feedback path connected between the output of the amplifier member and an input thereof which is inverting with respect to the output signals of the amplifier member, the improvement wherein the components defining said feedback path comprise an electronically voltage-controllable resistor having a control voltage input and a first frequency dependent impedance connected in parallel with said resistor, and said circuit further comprises a second frequency dependent impedance connected between the inverting input of said amplifier member and a point at the circuit reference potential, and means for supplying the control voltage to the control voltage input of said controllable resistor.
In an amplifier circuit arranged to be connected in a useful signal path and having a variable transmission factor and an effective transmission frequency band delimited by a lower limit frequency which can be varied as a function of a control voltage, the circuit including an amplifier member and circuit components defining a feedback path connected between the output of the amplifier member and an input thereof which is inverting with respect to the output signal of the amplifier member, the improvement wherein the components defining said feedback path comprise a first electronically voltage-controllable resistor having a control voltage input, and a first frequency dependent impedance connected in parallel with said first resistor, and said circuit further comprises a second electronically voltage-controllable resistor having a control input, said second resistor being connected in the useful signal path and to an input of said amplifier member which is inverting with respect to the output signals of said amplifier member, a second frequency dependent impedance connected in parallel with said second resistor, and means for supplying the control voltage to the control voltage inputs of said first and second controllable resistors.
Dependencies are inferred from the claim text.