Offset voltage trimming circuit
AssigneeMitsumi Electric Co., Ltd.
InventorsAkira Ikeuchi, Kyozo Makime
Life of this patent
Estimating the term…
Abstract
An offset voltage trimming circuit for sending a current from a constant-current source to a trimming resistor and thus obtaining an offset voltage, the offset voltage trimming circuit having a Zener diode with a temperature characteristic of zero, a transistor connected so as to form a diode and connected in series to the Zener diode, a current-mirror circuit connected to the transistor and a second resistor connected in series to the current-mirror circuit and having a temperature characteristic identical to that of the trimming resistor, with the current being supplied to the trimming resistor from the current-mirror circuit in order to prevent changes in the offset voltage due to changes in temperature.
Claims5
An offset voltage trimming circuit for sending a current from a constant-current source to a first resistor and thus obtaining an offset voltage, said offset voltage trimming circuit comprising:
- a Zener diode with a temperature characteristic of zero;
- a transistor connected so as to form a diode and connected in series to the Zener diode;
- a current-mirror circuit connected to the transistor;
- and
- a second resistor connected in series to the current-mirror circuit and having a temperature characteristic identical to that of the first resistor,
- the current being supplied to the first resistor from the current-mirror circuit.
An offset voltage trimming circuit comprising:
- a differential amplifier circuit outputting an offset voltage;
- a first resistor connected to the differential amplifier circuit;
- and
- a pair of constant-current sources connected to the differential amplifier circuit,
- each of the pair of constant-current sources comprising:
- a Zener diode with a temperature characteristic of zero;
- a transistor connected so as to form a diode and connected in series to the Zener diode;
- a current-mirror circuit connected to the transistor;
- and
- a second resistor connected in series to the current-mirror circuit and having a temperature characteristic identical to that of the first resistor,
- the current being supplied to the first resistor from the current-mirror circuit.
A constant-current source comprising:
- a Zener diode with a temperature characteristic of zero;
- a transistor connected so as to form a diode and connected in series to the Zener diode;
- a current-mirror circuit connected to the transistor;
- and
- a resistor connected in series to the current-mirror circuit and having a temperature characteristic identical to that of another resistor provided in a circuit to which a current is supplied from the current-mirror circuit.
Dependencies are inferred from the claim text.