Citizen Watch Company, Ltd.

Yukio Otaka

Shigeru Morokawa

Takakazu Yano

Rikoku Nakamura

Ryoji Iwakura

Katsuyoshi Aihara

Shinichi Komine

A crystal oscillator circuit using CMOSFETs including an oscillator circuit that is constructed of a resonating section and an amplifying section having a CMOSFET, a reference current source circuit for generating a reference current which determines a bias current of the amplifying section, and a control signal generator circuit for controlling the reference current source circuit to make a bias current larger than that in the oscillation status when the oscillator circuit is in the non-oscillation status. As a result, the reference current source circuit constant-current biases the DC bias of the amplifying section without depending on the source voltage. Therefore, it can lower the driving source voltage of the oscillator circuit. Further, only the bias current of the amplifying section is increased during the oscillation starting period of the oscillator circuit, so that the oscillator circuit can provide a stable oscillation with low power, without variations in the source voltage.

Crystal oscillator circuit using CMOSFETs

In an electronic timepiece, in which electric power generated by a solar cell (,) is accumulated in an accumulator device (,) and a time keeping means (,) is driven with the accumulated electric power, an electrically on-off controllable switch (,) is provided in a circuit for charging the accumulator device (,) by the solar cell (,), a voltage comparison means (,) intermittently brings the switch (,) into the off-state at predetermined intervals and compares the generated voltage (Vs) by the solar cell and the accumulated voltage (Vb) in the accumulator device (,), and keeps the switch (,) in the off-state as it is when Vs&lE;Vb and brings the switch (,) into the on-state when Vs>Vb in accordance with the comparison result. Thereby, a reverse flow of an electric current from the accumulator device (,) can be prevented and a voltage drop on charging is eliminated, resulting in enhancement in charging efficiency.

Electronic timepiece

Growing community of inventors

Tokorozawa, Japan

Yukio Otaka