Quick starting oscillator circuit having low power consumption

Abstract

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.