Threshold extracting method and circuit using the same

A transistor threshold voltage extraction circuit having an output, comprising:

• at least two transistors of the same type having substantially a same threshold voltage level, each of the transistors having a control terminal, a first main conduction terminal and a second main conduction terminal;
• a current mirror circuit having an input terminal and an output terminal coupled respectively to said two transistors to supply bias currents to the two transistors;
• a voltage generator connected between said two control terminals, said voltage generator including a two-terminal circuit element and a bias network to provide a constant predetermined current through the two-terminal circuit element;
• a feedback path between said control terminals and one of said input and output terminals of the current mirror circuit;
• and
• wherein said output of the voltage extraction circuit is coupled to one of said control terminals.

A transistor threshold voltage extraction circuit having an output, comprising:

• at least two transistors of the same type having substantially a same threshold voltage level, each of the transistors having a control terminal, a first main conduction terminal and a second main conduction terminal;
• a current mirror circuit having an input terminal and an output terminal coupled respectively to said two transistors to supply bias currents to the two transistors;
• a voltage generator connected between said two control terminals;
• a feedback path between said control terminals and one of said input and output terminals of the current mirror circuit;
• a voltage divider having an intermediate output and first and second end terminals, the voltage divider including two-terminal circuit elements and wherein said first main conduction terminals are coupled to a third reference potential, the second main conduction terminal of a first transistor of said two transistors is coupled to the input terminal of said mirror circuit, the second main conduction terminal of a second transistor of said two transistors is coupled to the output terminal of said mirror circuit, the control terminal of said second transistor is coupled to said intermediate output and the control terminal of said first transistor is coupled to said first end terminal, said first end terminal is coupled to a second reference potential for bias of said divider and in which said output is coupled to said second end terminal;
• and
• wherein said output of the voltage extraction circuit is coupled to one of said control terminals.

A circuit comprising:

• an operating circuit block;
• a transistor threshold voltage extraction circuit having an output, including:
• at least two transistors of the same type having substantially a same threshold voltage level, each of the transistors having a control terminal, a first main conduction terminal and a second main conduction terminal;
• a current mirror circuit having an input terminal and an output terminal coupled respectively to said two transistors to supply bias currents to the two transistors;
• a voltage generator connected between said two control terminals, said voltage generator including a two-terminal circuit element and a bias network to provide a constant predetermined current through the two-terminal circuit element;
• a feedback path between said control terminals and one of said input and output terminals of the current mirror circuit;
• and
• wherein said output of the voltage extraction circuit is coupled to one of said control terminals;
• and
• at least one bias network having an input connected to said output and having an output connected to said operating circuit block to bias the circuit block.

A circuit comprising:

• an operating circuit block;
• a transistor threshold voltage extraction circuit having an output, including:
• at least two transistors of the same type having substantially a same threshold voltage level, each of the transistors having a control terminal, a first main conduction terminal and a second main conduction terminal;
• a current mirror circuit having an input terminal and an output terminal coupled respectively to said two transistors to supply bias currents to the two transistors;
• a voltage generator connected between said two control terminals, said voltage generator including a voltage divider having an intermediate output and first and second end terminals, the voltage divider including two-terminal circuit elements and wherein said first main conduction terminals are coupled to a third reference potential, the second main conduction terminal of a first transistor of said two transistors is coupled to the input terminal of said mirror circuit, the second main conduction terminal of a second transistor of said two transistors is coupled to the output terminal of said mirror circuit, the control terminal of said second transistor is coupled to said intermediate output and the control terminal of said first transistor is coupled to said first end terminal, said first end terminal is coupled to a second reference potential for bias of said divider and in which said output is coupled to said second end terminal;
• a feedback path between said control terminals and one of said input and output terminals of the current mirror circuit;
• and
• wherein said output of the voltage extraction circuit is coupled to one of said control terminals;
• and
• at least one bias network having an input connected to said output and having an output connected to said operating circuit block to bias the circuit block.

A circuit comprising:

• an operating circuit block;
• a transistor threshold voltage extraction circuit having an output, including:
• at least two transistors of the same type having substantially a same threshold voltage level, each of the transistors having a control terminal, a first main conduction terminal and a second main conduction terminal;
• a current mirror circuit having an input terminal and an output terminal coupled respectively to said two transistors to supply bias currents to the two transistors;
• a voltage generator connected between said two control terminals;
• a feedback path between said control terminals and one of said input and output terminals of the current mirror circuit;
• wherein said output of the voltage extraction circuit is coupled to one of said control terminals;
• at least third and fourth transistors of the same type each having a control terminal and a threshold voltage substantially equal to the threshold voltage of the at least two transistors, the control terminal of said third transistor being coupled to said control terminals of said at least two transistors;
• a second current mirror circuit having at least one input terminal and one output terminal, said input terminal and said output terminal being coupled respectively to said third and fourth transistors to provide bias currents;
• and
• wherein said output is coupled to the connection of the control terminal of said fourth transistor and of the output terminal of said mirror circuit;
• and
• at least one bias network having an input connected to said output and having an output connected to said operating circuit block to bias the circuit block.

A circuit for determining a threshold voltage of a transistor comprising:

• a current mirror circuit having at least two input-output terminals;
• at least two transistors each of the transistors having a control terminal and each having substantially a same threshold voltage, each of the transistors being coupled to one of the input-output terminals of the current mirror circuit to receive bias currents;
• means for providing a potential difference between said two control terminals of the at least two transistors;
• and
• means for determining the same threshold voltage of each of the at least two transistors.