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US 6,304,138 B1Granted
Audio-frequency power amplifier that utilizes a bridged amplified configuration
AssigneeNational Semiconductor Corporation
InventorNicky M. Johnson
Life of this patent
Estimating the term…
Abstract
An audio-frequency power bridged amplifier operates without a negative rail when responding to non-negative input signals, e.g. input signals ranging from zero to five volts. The amplifier also eliminates the problem of one differential rail being clipped before the other differential rail. When combined with a tracking circuit to form a Class H amplifier, the Class H amplifier operates with two positive rails rather than the two positive and two negative rails conventionally used with Class H amplifiers.
Claims37
An amplifier comprising:
- a first operational amplifier (op amp) having a negative input connected to a first intermediate node, a positive input directly connected to a second intermediate node, and an output connected to a first output node;
- a second op amp having a negative input directly connected to the second intermediate node, a positive input connected to a reference voltage, and an output connected to a second output node;
- a first feedback resistor connected between the output and the negative input of the first op amp;
- and
- a second feedback resistor connected between the output and the negative input of the second op amp;
- a first input resistor connected between the negative input of the first op amp and the reference voltage;
- and
- a second input resistor connected between the negative input of the second op amp and an input node.
5 more elements
An amplifier comprising:
- a first operational amplifier (op amp) having a negative input connected to a first intermediate node, a positive input connected to a second intermediate node, and an output connected to a first output node, the first op amp being connected to an upper supply rail and a lower supply rail, the lower supply rail being a non-negative value;
- a second op amp having a negative input connected to the second intermediate node, a positive input connected to a reference voltage, and an output connected to a second output node, the second op amp being connected to an upper supply rail and a lower supply rail, the reference voltage being substantially equal to one-half the difference between the upper supply rail and the lower supply rail;
- a first feedback resistor connected between the output and the negative input of the first op amp;
- a second feedback resistor connected between the output and the negative input of the second op amp;
- a first input resistor connected between the negative input of the first op amp and the reference voltage;
- and
- a second input resistor connected between the negative input of the second op amp and an input node.
4 more elements
An amplifier comprising:
- a first operational amplifier (op amp) having a negative input connected to a first intermediate node, a positive input connected to a second intermediate node, and an output connected to a first output node, the first op amp being connected to an upper supply rail and a lower supply rail, the lower supply rail being a non-negative value;
- a second op amp having a negative input connected to the second intermediate node, a positive input connected to a reference voltage, and an output connected to a second output node, the second op amp being connected to an upper supply rail and a lower supply rail, the reference voltage being equal to a value that is less than one-half the difference between the upper supply rail and the lower supply rail;
- a first feedback resistor connected between the output and the negative input of the first op amp;
- a second feedback resistor connected between the output and the negative input of the second op amp;
- a first input resistor connected between the negative input of the first op amp and the reference voltage;
- and
- a second input resistor connected between the negative input of the second op amp and an input node.
4 more elements
An amplifier comprising:
- a first operational amplifier (op amp) having a negative input connected to a first intermediate node, a positive input connected to a second intermediate node, and an output connected to a first output node, the first op amp being connected to an upper supply rail and a lower supply rail;
- a second op amp having a negative input connected to the second intermediate node, a positive input connected to a reference voltage, and an output connected to a second output node, the second op amp being connected to an upper supply rail and a lower supply rail, the reference voltage being equal to a value that is less than one-half the difference between the upper supply rail and the lower supply rail;
- a first feedback resistor connected between the output and the negative input of the first op amp;
- a second feedback resistor connected between the output and the negative input of the second op amp;
- a first input resistor connected between the negative input of the first op amp and the reference voltage;
- and
- a second input resistor connected between the negative input of the second op amp and an input node.
4 more elements
An amplifier comprising:
- a first operational amplifier (op amp) having a negative input connected to a first intermediate node, a positive input connected to a second intermediate node, and an output connected to a first output node, the first op amp being connected to an upper supply rail and a lower supply rail, the first op amp outputting a first voltage;
- a second op amp having a negative input connected to the second intermediate node, a positive input connected to a reference voltage, and an output connected to a second output node, the second op amp being connected to an upper supply rail and a lower supply rail, the second op amp outputting a second voltage, the first voltage being equal to the reference voltage when the second voltage is equal to or greater than the lower supply rail, and the voltages on the positive and negative inputs of the second op amp are the same;
- a first feedback resistor connected between the output and the negative input of the first op amp;
- a second feedback resistor connected between the output and the negative input of the second op amp;
- a first input resistor connected between the negative input of the first op amp and the reference voltage;
- and
- a second input resistor connected between the negative input of the second op amp and an input node.
4 more elements
An amplifier comprising;
- an amplifying device including:
- a first operational amplifier (op amp) having a negative input connected to a first intermediate node, a positive input connected to a second intermediate node, an output connected to a first output node, a first upper supply input, and a first lower supply input;
- a second operational amplifier (op amp) having a negative input connected to the second intermediate node, a positive input connected to a reference voltage, an output connected to a second output node, a second upper supply input, and a second lower supply input;
- a first feedback resistor connected between the output and the negative input of the first op amp;
- a second feedback resistor connected between the output and the negative input of the second op amp;
- a first input resistor connected between the negative input of the first op amp and the reference voltage;
- a second input resistor connected between the negative input of the second op amp and an input node, and
- a tracking circuit connected to the outputs of the first and second op amps, and the first and second upper supply inputs of the first and second op amps.
5 more elements
An amplifier comprising:
- a first operational amplifier (op amp) having a negative input, a positive input, and an output;
- a second op amp having a negative input directly connected to the positive input of the first op amp, a positive input, and an output;
- a first feedback resistor connected between the output and the negative input of the first op amp;
- and
- a second feedback resistor connected between the output and the negative input of the second op amp.
2 more elements
An amplifier comprising:
- a first operational amplifier (op amp) having a negative input, a positive input, and an output;
- a second op amp having a negative input, a positive input connected to a reference node, and an output;
- a first feedback resistor connected between the output and the negative input of the first op amp;
- a second feedback resistor connected between the output and the negative input of the second op amp;
- and
- a reference resistor directly connected to the negative input of the first op amp and the reference node.
3 more elements
An amplifier comprising:
- an input node having an input voltage, an amplitude of the input voltage varying over time in response to an input signal;
- a control node coupled to the input node, the control node having a control voltage;
- a first resistor;
- a first operational amplifier (op amp) having a positive input coupled to the control node, a negative input coupled to the first resistor, and a first output coupled to the first resistor, the first output having a first voltage, the first op amp outputting the first voltage with a substantially constant amplitude when the control voltage is equal to a control value, and varying an amplitude of the first voltage in response to the control voltage varying from the control value;
- a second resistor;
- a second op amp having a positive input, a negative input coupled to the control node and the second resistor, and a second output coupled to the second resistor, the second output having a second voltage, the second op amp varying an amplitude of the second voltage within a range bounded by a lower voltage and an upper voltage in response to variations in the input voltage to drive the control voltage to be equal to the control value, outputting the lower voltage when a third voltage less than the lower voltage is required to drive the control voltage to be equal to the control value, and outputting the upper voltage when a fourth voltage greater than upper voltage is required to drive the control voltage to be equal to the control value, the control voltage varying from the control value when the third voltage is required to drive the control voltage to be equal to the control value, the control voltage varying from the control value when the fourth voltage is required to drive the control voltage to be equal to the control value.
3 more elements
Dependencies are inferred from the claim text.