Variable resistance circuit, oscillator circuit, and semiconductor device

Patent metadata

Field	Value
Publication number	US-10714243-B2
Application number	US-201916284678-A
Country	US
Kind code	B2
Filing date	Feb 25, 2019
Priority date	Feb 26, 2018
Publication date	Jul 14, 2020
Grant date	Jul 14, 2020

Abstract

Provided is a variable resistance circuit in which the resistance value of the variable resistance circuit can be accurately adjusted, by reducing the error in the change amount of the resistance value of the variable resistance circuit due to the on-resistances of switch circuits even if the switch circuits that each bypass a resistor included in a ladder resistor circuit are switched between an OFF state and an ON state. This variable resistance circuit includes: a ladder resistor circuit including a plurality of resistors; a first switch circuit connected in series to one end of one resistor of the plurality of resistors; and a second switch circuit connected in parallel to a series circuit of the one resistor and the first switch circuit. When one of the first and second switch circuits is turned on, the other of the first and second switch circuits is turned off.

First claim

What is claimed is:

1. A variable resistance circuit comprising:
a first resistance sub-circuit having:
a first resistor;
a first switch circuit connected in series to one end of the first resistor; and
a second switch circuit connected in parallel to a series circuit of the first resistor and the first switch circuit; and

a second resistance sub-circuit connected in series with the first resistance sub-circuit, the second resistance sub-circuit having:
a second resistor; and
a third switch circuit connected in parallel to the second resistor,

wherein, when one of the first and second switch circuits is turned on, the other of the first and second switch circuits is turned off, the first and second resistance sub-circuits form a ladder resistor circuit, and a switch circuit connected in series with the second resistor is not provided in the second resistance sub-circuit.

2. The variable resistance circuit according to claim 1 , further comprising:
an additional first resistance sub-circuit in the ladder resistor circuit.

3. The variable resistance circuit according to claim 1 , wherein the first switch circuit, the second switch circuit, and the third switch circuit each include a same number of switch elements.

4. The variable resistance circuit according to claim 1 , wherein the first switch circuit, the second switch circuit, and the third switch circuit each has a same on-resistance.

5. An oscillator circuit comprising:
a charging and discharging type oscillator configured to perform an oscillation operation at an oscillation frequency according to the amount of a control current; and
a control current generation unit that includes the variable resistance circuit according to claim 1 , and is configured to generate the control current based on an output voltage of a temperature sensor using a resistance value of the variable resistance circuit that is set by a control signal.

6. An oscillator circuit comprising:
a charging and discharging type oscillator configured to perform an oscillation operation at an oscillation frequency according to the amount of a control current; and
a control current generation unit that includes the variable resistance circuit according to claim 2 , and is configured to generate the control current based on an output voltage of a temperature sensor using a resistance value of the variable resistance circuit that is set by a control signal.

7. An oscillator circuit comprising:
a charging and discharging type oscillator configured to perform an oscillation operation at an oscillation frequency according to the amount of a control current; and
a control current generation unit that includes the variable resistance circuit according to claim 3 , and is configured to generate the control current based on an output voltage of a temperature sensor using a resistance value of the variable resistance circuit that is set by a control signal.

8. An oscillator circuit comprising:
a charging and discharging type oscillator configured to perform an oscillation operation at an oscillation frequency according to the amount of a control current; and
a control current generation unit that includes the variable resistance circuit according to claim 4 , and is configured to generate the control current based on an output voltage of a temperature sensor using sensor using a resistance value of the variable resistance circuit that is set by a control signal.

9. A semiconductor device comprising the variable resistance circuit according to claim 1 .

10. A semiconductor device comprising the variable resistance circuit according to claim 2 .

11. A semiconductor device comprising the variable resistance circuit according to claim 3 .

12. A semiconductor device comprising the variable resistance circuit according to claim 4 .

Assignees

• Seiko Epson Corp

Inventors

• Kikuchi Takahiro
• Kuwano Toshikazu
• Abe Sachiyuki
• Kawaguchi Shuji

Classifications

• H03K3/011

  Modifications of generator to compensate for variations in physical values, e.g. voltage, temperature {(to maintain energy constant H03K3/015)} · CPC title

• H01C1/16

  Resistor networks not otherwise provided for · CPC title

• H03K4/501

  the starting point of the flyback period being determined by the amplitude of the voltage across the capacitor, e.g. by a comparator · CPC title

• H03K3/03

  Astable circuits · CPC title

• H01C10/50 Primary

  structurally combined with switching arrangements (H01C10/36 takes precedence) · CPC title