Panasonic Corporation

Matsushita Electric Industrial Co., Ltd.

Keigo Shingu

Hisato Takeuchi

Kei Nagatomo

Eiichi Kaminishi

Takashi Ootsuka

Motoki Sakai

A temperature-compensated crystal oscillator includes a mode selector circuit, a control logic serial&#x2022;interface, a PROM circuit, an oscillation control circuitand an oscillation circuit, and has, as terminals, a power terminal (VCC/CLK), an input terminal (VC/DATA/PE), an output terminal (OUT)and a ground terminal (GND). The mode selector circuitswitches the crystal oscillator to an emulation mode when a first signal in which a power voltage and a clock signal supplied through the power terminalare superimposed, is inputted from the power terminal and a second signal having a predetermined pattern is inputted from the input terminal

IC for control of temperature-compensated crystal oscillator

A first order function generation circuit receives a signal from a temperature sensor circuit, and generates a first order function control signal Vthat is affected by the ambient temperature. A fourth order and fifth order approximation function generation circuit receives signals from the temperature sensor circuit and from the third order approximation function generation circuit, and generates a fourth and fifth order approximation function control signal Vthat is affected by the ambient temperature. A peak change point adjustment circuit outputs a signal to adjust the value of a peak change point temperature Ti for the third order approximation function generation circuit, the first order generation function circuit and the fourth order and fifth order approximation function generation circuit. A temperature compensation circuit adds together control signals V, V, Vand V, and outputs the resultant signal Vc.

Function generation circuit

The object of the present invention is to provide a crystal oscillator with one IC capable of effectively responding to specifications or a frequency of an installed set, an output terminal of the oscillatoris connected to an input terminal of the inverteran output terminal of which is connected to the first resistorand one terminal of the second resistorthe other terminal of the first resistoris connected to one terminal of the first capacitorand an input terminal of the first transistorthe other terminal of the first capacitoris connected to one terminal of the first switchand the other terminal of the first switchis grounded, the other terminal of the second resistoris connected to one terminal of the second capacitorand an input terminal of the second transistorthe other terminal of the second capacitoris connected to one terminal of the second switchand the other terminal of the second switchis grounded, an output terminal of the first transistorand an output terminal of the second transistorare connected to the oscillation output terminaland the first switchand the second switchare controlled by the storage device

Output circuit for oscillator

An oscillator starting control circuit capable of shortening a starting time and stably controlling the starting time, and furthermore, stabilizing an oscillating frequency after starting an oscillating circuit. An oscillating circuit () is a crystal oscillating circuit in which an input and an output of an inverter () are connected to both ends of a crystal oscillator () and both ends of a resistor (), the input is connected to a drain of an MOS variable capacity (), the output is connected to a drain of an MOS variable capacity (), a source of the MOS variable capacity () is connected to a fixed capacity (), a source of the MOS variable capacity () is connected to a fixed capacity (), and the other ends of the fixed capacities () are connected to a GND.

Oscillator starting control circuit

In a voltage controlled oscillator including an amplifier, a feedback circuit and a crystal oscillator, two MOS transistors M, Mare connected for use as variable capacity elements for the frequency adjustment of the voltage controlled oscillator. Drains of the MOS transistors M, Mare respectively connected to an XT terminal and an XTB terminal of the crystal oscillator. Sources of the MOS transistors M, Mare made common and connected to a grounding terminal via a capacitor C. Gates of the MOS transistors M, Mare made common, and an added voltage signal of a temperature compensating signal voltage and an external frequency control signal voltage is applied to the common gate terminals of the MOS transistors to thereby perform the frequency control of the oscillator.

Voltage controlled oscillator

With first, second and third current exchanger circuits cascaded, a current in proportion to a difference between an ambient temperature Ta and a reference temperature Tr is input to the first current exchanger circuit. The first current exchanger circuit supplies a current in proportion to the square of Ta&#x2212;Tr to the second current exchanger circuit, the second current exchanger circuit supplies a current in proportion to the fourth power of Ta&#x2212;Tr to the third current exchanger circuit, and the third current exchanger circuit outputs a current in proportion to the fifth power of Ta&#x2212;Tr. Each of the first, second and third current exchanger circuits has a configuration which does not require a high supply voltage enough to drive a series circuit of three or more diodes.

Growing community of inventors

Tokyo, Japan

Keigo Shingu