Semiconductor device
AssigneeRenesas Electronics Corporation
InventorMasahiro Araki
Life of this patent
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Abstract
A semiconductor device containing a terminal, a power supply voltage dropping circuit that generates a constant voltage, a switch circuit to periodically apply a constant voltage to a terminal in response to a first clock, a current-controlled oscillator circuit, and a counter, and in which the power supply voltage dropping circuit supplies a first current to the switch circuit, the current-controlled oscillator circuit generates a second clock whose frequency changes in response to the value of the first current, and the counter counts the number of second clocks within the counting time.
Claims14
A semiconductor device comprising:
- a terminal;
- a power supply voltage dropping circuit that generates a constant voltage and includes a first transistor that outputs a first current;
- a switch circuit that is supplied with the first current and that periodically applies the constant voltage to the terminal in response to a first clock;
- a first current-controlled oscillator circuit that generates a second clock;
- a first counter that counts the second clock in a counting time;
- and
- a current mirror circuit that includes the first transistor and a second transistor, and the second transistor supplies a second current to the first current-controlled oscillator circuit,
- wherein a frequency of the second clock changes in response to a value of the first current and a value of the second current.
A semiconductor device comprising:
- a terminal;
- a power supply voltage dropping circuit that generates a constant voltage;
- a switch circuit that periodically applies the constant voltage to the terminal in response to a first clock;
- a first current-controlled oscillator circuit;
- and
- a first counter,
- wherein the power supply voltage dropping circuit supplies a first current to the switch circuit,
- wherein the first current-controlled oscillator circuit generates a second clock whose frequency changes in response to a value of the first current,
- wherein the first counter counts the second clock in a counting time,
- wherein the semiconductor device further comprises:
- a second transistor,
- wherein the power supply voltage dropping circuit includes a first transistor that outputs the first current,
- wherein a current mirror circuit includes the first transistor and the second transistor, and
- wherein the second transistor supplies a second current to the first current-controlled oscillator circuit.
A semiconductor device comprising:
- a terminal;
- a power supply voltage dropping circuit that generates a constant voltage and includes a first transistor that outputs a first current;
- a switch circuit that is supplied with the first current and that periodically applies the constant voltage to the terminal in response to a first clock;
- a first current-controlled oscillator circuit that generates a second clock;
- a first counter that counts the second clock in a counting time;
- a current mirror circuit that includes the first transistor and a second transistor, and the second transistor supplies a second current to the first current-controlled oscillator circuit;
- and
- a touch electrode coupled to the terminal,
- wherein a frequency of the second clock changes in response to a value of the first current and a value of the second current, and
- wherein a value of the first current changes in response to a change in a parasitic capacitance value of the touch electrode coupled to the terminal.
Dependencies are inferred from the claim text.