Mitsumi Electric Company Ltd.

Shigemitsu Watanabe

Hiromi Katoh

Tsukasa Yamada

Tadashi Ono

Akira Shiga

Ryuichi Sada

Masaki Kasahara

Shin-ichi Sakaguchi

Kiyohide Sakihama

Masato Shimoyama

A differential amplifier produces a collector current of an output side transistor as an output current signal. In this case, a power supply voltage or a closer voltage to the power supply voltage is supplied to a collector terminal of the output side transistor. First and second current mirror circuits produce a current signal in response to the output current signal. The produced current signal passes through a resistor, a terminal of which is connected to a reference voltage. When the produced current signal passes through the resistor, a voltage drop from the reference voltage occurs at the resistor. By utilizing the voltage drop at the resistor, an output voltage changing in response to two output voltage signals is produced.

Differential amplifier device

A temperature-compensated quartz oscillator comprises a stabilized power supply circuit (1) for supplying a constant voltage, an oscillation circuit (2) comprising a quartz resonator (21) and a varicap (22), a temperature detecting circuit (3) for producing a detected voltage signal (V.sub.Temp) corresponding to an oscillator part temperature by the use of the temperature-voltage characteristic of a temperature detecting element located in the vicinity of the oscillation circuit (2), and a temperature characteristic compensating portion (4) for producing through analog processing of the detected voltage signal (V.sub.Temp) a varicap control voltage signal (V.sub.VR) to be supplied to the varicap (22).

Crystal oscillator with a temperature-compensating analog circuit

Adjusting elements (R1, R2 and R3) are redundantly or preliminarily built in an IC circuit body (5), the adjusting elements (R1, R2 and R3) are connected to one another through conductor patterns (P1, P2 and P3) provided outside the circuit body (5), and after the circuit operating function is confirmed by inspection, the conductor patterns (P1, P2 and P3) are selectively cut to select an adjusting element to be used, thereby to adjust or select a function of the circuit body.

Method for adjusting the circuit characteristic of a circuit body by

Supplied with a power source, an output level of an oscillating circuit gradually increases until the oscillator circuit reaches its steady oscillation. A level monitor monitors the output level, and produces a control signal if the output level is less than a predetermined level. A current producing circuit receives the control signal and produces a boost current to increase a collector current at an oscillating transistor. The output level of the oscillating circuit suddenly increases as the collector current increases. After the output level of the oscillator reaches the predetermined level, the level monitor stops production of the control signal. Therefore, the boost current stops. As a result, the collector current of the oscillating transistor has a predetermined value dependent on the circuit structure of the oscillating circuit. Thus, only before the output level reaches the predetermined level, the collector current of the oscillating transistor is brought to an increased level, and after the output level reaches the predetermined level, the value of the collector current is decreased to a predetermined value. Therefore, the oscillator starts quickly, suppressing the increase of the power consumption even when the oscillator is intermittently driven.

Quick starting oscillator circuit having low power consumption

An object of the invention is to provide a method of forming a fine conductive pattern. The method allows the fine conductive pattern whose thickness is relatively large to be formed easily, accurately, and surely. An insulating layer is formed on a substrate. A pattern resist is formed on the insulating layer. Then, the insulating layer is etched downward based on a profile of the pattern resist in a first etching step, and sidewalls of each of groove portions formed by the etching step of the insulating layer are etched sideways in a second etching step, so that overhang portions are defined at the lower edges of the pattern resist portions. Then, conductive film portions are formed by depositing a conductor on the pattern resist, and conductive films that are on the pattern resist are lifted off, so that a fine conductor pattern can be prepared.

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Kanagawa, Japan

Shigemitsu Watanabe