US 2007/0182499 A1Published application

Oscillation circuit

OwnerKatsushi Wakai, Ichiro Yamane +2inventors

InventorsKatsushi Wakai, Ichiro Yamane, Toshifumi Hamaguchi, Kazuhisa Raita

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Abstract

A first comparator outputs a first signal indicative that a voltage determined according to the amount of charge stored in a first capacitor has reached a first reference voltage. A second comparator outputs a second signal indicative that a voltage determined according to the amount of charge stored in a second capacitor has reached a second reference voltage. An RS flip flop circuit is shifted to a set state by one of the first signal and the second signal and shifted to a reset state by the other signal. When the RS flip flop circuit is in the set state, the first capacitor is in a charge state, and the second capacitor is in a discharge state. When the RS flip flop circuit is in the reset state, the first capacitor is in a discharge state, and the second capacitor is in a charge state.

Claims10

Dependent claims

An oscillation circuit, comprising:

first and second capacitors which are charged or discharged by a current generated by a constant current source;
a first comparator for comparing a first voltage which is determined according to the amount of charge stored in the first capacitor with a first reference voltage to output a first signal indicative that the first voltage has reached the first reference voltage;
a second comparator for comparing a second voltage which is determined according to the amount of charge stored in the second capacitor with a second reference voltage to output a second signal indicative that the second voltage has reached the second reference voltage;
an RS flip flop circuit which is shifted to a set state by one of the first signal and the second signal and shifted to a reset state by the other signal;
a first charge/discharge control circuit for controlling the first capacitor such that, when the RS flip flop circuit is in the set state, the first capacitor is in a charge state, and when the RS flip flop circuit is in the reset state, the first capacitor is in a discharge state;
and
a second charge/discharge control circuit for controlling the second capacitor such that, when the RS flip flop circuit is in the reset state, the second capacitor is in a charge state, and when the RS flip flop circuit is in the set state, the second capacitor is in a discharge state.

4 more elements

An oscillation circuit, comprising:

first and second capacitors which are charged or discharged by a current generated by a constant current source;
a first comparator for comparing a first voltage which is determined according to the amount of charge stored in the first capacitor with a first reference voltage to output a first signal indicative that the first voltage has reached the first reference voltage;
a second comparator for comparing a second voltage which is determined according to the amount of charge stored in the second capacitor with a second reference voltage to output a second signal indicative that the second voltage has reached the second reference voltage;
a first RS flip flop circuit which is shifted to the set state when the first signal is output by the first comparator and which is shifted to the reset state when the second signal is output by the second comparator while the first RS flip flop circuit is in the set state;
a second RS flip flop circuit which is shifted to the set state when the second signal is output by the second comparator and which is shifted to the reset state when the first signal is output by the first comparator while the second RS flip flop circuit is in the set state;
a toggle flip flop circuit whose output is inverted when the first RS flip flop circuit shifts from the reset state to the set state and when the second RS flip flop circuit shifts from the reset state to the set state;
and
a charge/discharge control circuit which selectively switches according to an output of the toggle flip flop circuit between a mode where the first capacitor is charged and the second capacitor is discharged and a mode where the first capacitor is discharged and the second capacitor is charged.

5 more elements

An oscillation circuit, comprising:

any one of a charge-based first capacitor/comparator set and a discharge-based first capacitor/comparator set;
and
any one of a charge-based second capacitor/comparator set and a discharge-based second capacitor/comparator set, wherein
the charge-based first capacitor/comparator set includes
a first capacitor which is charged by a current generated by a constant current source, and
a first comparator which outputs a first signal during a period extending from a time when a voltage determined according to the amount of charge stored in the first capacitor is increased to a first reference voltage by the charging of the first capacitor to a time when the voltage decreases to a second reference voltage which is lower than the first reference voltage,
the discharge-based first capacitor/comparator set includes
a first capacitor which is discharged by a current generated by a constant current source, and
a first comparator which outputs a first signal during a period extending from a time when a voltage determined according to the amount of charge stored in the first capacitor is decreased to a first reference voltage by the discharging of the first capacitor to a time when the voltage increases to a second reference voltage which is higher than the first reference voltage,
the charge-based second capacitor/comparator set includes
a second capacitor which is charged by a current generated by a constant current source, and
a second comparator which outputs a second signal during a period extending from a time when a voltage determined according to the amount of charge stored in the second capacitor is increased to a third reference voltage by the charging of the second capacitor to a time when the voltage decreases to a fourth reference voltage which is lower than the third reference voltage,
the discharge-based second capacitor/comparator set includes
a second capacitor which is discharged by a current generated by a constant current source, and
a second comparator which outputs a second signal during a period extending from a time when a voltage determined according to the amount of charge stored in the second capacitor is decreased to a third reference voltage by the discharging of the second capacitor to a time when the voltage increases to a fourth reference voltage which is higher than the third reference voltage, and
the oscillation circuit further comprises
a toggle flip flop circuit whose output is inverted every time any of the first signal and the second signal is output, and
a charge/discharge control circuit which selectively switches according to an output of the toggle flip flop circuit between a mode where the first capacitor is charged and the second capacitor is discharged and a mode where the first capacitor is discharged and the second capacitor is charged.

15 more elements

Dependencies are inferred from the claim text.