Absolute value circuit
AssigneeIntersil Americas Inc.
InventorHarold Allen Wittlinger
Life of this patent
Estimating the term…
Abstract
An absolute value circuit includes an operational amplifier, the output of which is coupled to control inputs of complementary polarity transistors having current flow paths therethrough coupled in series with inputs of current mirror amplifier stages. A common node of the current flow paths through the transistors is coupled to an input of the operational amplifier to which a current waveform is applied. The current mirror amplifier stages are configured so as to provide like polarity output currents. The outputs of the current mirror amplifier stages are combined to produce an output current that corresponds to a full wave rectification or absolute value of an input current coupled to the operational amplifier.
Claims14
A circuit for producing an output current waveform representative of the absolute value of an input current waveform comprising:
- an input port to which said input current waveform is coupled;
- an output port from which said output current waveform is derived;
- an operational amplifier having an input coupled to said input port and an output;
- a first current mirror circuit referenced to a first voltage and having an input and an output;
- a second current mirror circuit referenced to a second voltage and having an input and an output;
- a third current mirror circuit referenced to said first voltage and having an input and an output;
- first and second transistor devices having current flow paths therethrough coupled in series between the input of said first current mirror circuit and the input of said second current mirror circuit, and wherein control ports of said first and second transistor devices are coupled to the output of said operational amplifier;
- and wherein
- the outputs of said first and third current mirror circuits are coupled to said output port;
- and
- the output of said second current mirror circuit is coupled to the input of said third current mirror circuit.
A method of generating an output current waveform representative of the absolute value of an input current waveform comprising the steps of:
- (a) coupling said input current waveform to an operational amplifier and to the current flow path of first and second complementary transistor devices, coupled in series between inputs of first and second current mirror circuits referenced to opposite polarity voltages;
- (b) coupling an output of said operational amplifier to control inputs of said first and second complementary transistor devices;
- (c) coupling an output of one of said first and second current mirror circuits to a third current mirror circuit referenced to one of said opposite polarity voltages;
- and
- (d) combining an output of another of said first and second current mirror circuits and an output of said third current mirror circuit, to produce said output current waveform.
Dependencies are inferred from the claim text.