Method and circuit for increasing the output impedance of an inactive amplifier
AssigneeLinear Technology Corporation
InventorsWilliam H. Gross, John W. Wright
Life of this patent
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Abstract
A method and circuit for increasing the output impedance of an inactive amplifier is provided. The method and circuit allows an increased number of amplifiers to be coupled in parallel to a single transmission line for distributing a plurality of video or other electrical signals to a remote location. The method and circuit increasing the impedance of an amplifier feedback network during inactive operation using a bootstrapping technique (i.e., by driving the feedback network) so as to increase the overall impedance of the amplifier during such operation.
Claims65
An amplifier circuit having at least one input for receiving an input signal, an output for producing an output signal when the amplifying circuit is in an amplifying state, the amplifier circuit adapted to be coupled to a feedback network which monitors the output signal to generate a feedback signal to control the output during the amplifying state, the amplifier circuit comprising:
- a first amplifier for receiving the input signal and for producing the output signal;
- and
- a circuit coupled to drive the feedback network when the amplifier circuit is in a non-amplifying state to increase the effective impedance of the network,
- whereby the output impedance of the amplifier circuit is increased during said non-amplifying state.
A method for increasing the output impedance of an amplifier circuit, the amplifier circuit including at least one input for receiving an input signal, an output for producing an output signal when the amplifying circuit is in an amplifying state, and a first amplifier for receiving the input signal and for producing the output signal, the amplifier circuit adapted to be coupled to a feedback network which monitors the output signal to generate a feedback signal to control the output during the amplifying state, the method comprising the steps of:
- (a) deactivating the first amplifier to put said amplifier circuit into a non-amplifying state;
- and
- (b) driving the feedback network when the amplifier circuit is in the non-amplifying state to increase the effective impedance of the network.
An amplifier circuit having at least one input for receiving an input signal, an output for producing an output signal when the amplifying circuit is in an amplifying state, the amplifier circuit adapted to be coupled to a feedback means which monitors the output signal to generate a feedback signal to control the output during the amplifying state, the amplifier circuit comprising:
- means for receiving and amplifying the input signal to produce an amplified output signal;
- and
- means coupled for driving at least a portion of the feedback means when the amplifier circuit is in a non-amplifying state to increase the effective output impedance of the network,
- whereby the output impedance of the amplifier circuit is increased during said non-amplifying state.
An amplifier circuit having at least one input for receiving an input signal, an output for producing an output signal when the amplifying circuit is in an amplifying state, the amplifier circuit adapted to be coupled to a feedback network which monitors the output signal to generate a feedback signal to control the output during the amplifying state, the amplifier circuit comprising:
- a first amplifier for receiving the input signal and for producing the output signal, the first amplifier including:
- an input circuit for amplifying the input signal and having an inverting input and a non-inverting input, wherein the input signal is adapted to be coupled to one of said inverting input and non-inverting input;
- and
- a first buffer circuit for isolating said input circuit from said output and having a first buffer input and a first buffer output;
- and
- a circuit coupled to drive the feedback network when the amplifier circuit is in a non-amplifying state to increase the effective impedance of the network,
- whereby the output impedance of the amplifier circuit is increased during said non-amplifying state.
An amplifier circuit having at least one input for receiving an input signal, an output for producing an output signal when the amplifying circuit is in an amplifying state, the amplifier circuit adapted to be coupled to a feedback network which monitors the output signal to generate a feedback signal to control the output during the amplifying state, the amplifier circuit comprising:
- a first amplifier for receiving the input signal and for producing the output signal;
- and
- a first circuit for increasing the effective impedance of the feedback network when the amplifier circuit is in a non-amplifying state, wherein the first amplifier and the first circuit are monolithically integrated into a single integrated circuit,
- whereby the output impedance of the amplifier circuit is increased during said non-amplifying state.
Dependencies are inferred from the claim text.