OSCILLATOR IMPROVED IN OSCILLATION CHARACTERISTIC AT OSCILLATION STARTING TIME AND OSCILLATING METHOD

摘要

PROBLEM TO BE SOLVED: To stably start an oscillator provided with a resonator which is influenced at its vibrating level at the starting time by providing a means which detects the start of oscillation and a means which sets the value of a control signal which secures the start of oscillation when the oscillator is turned on. ;SOLUTION: The signal selector 20 of an oscillator makes a voltage reference signal on a line 18 to be inputted to an amplifier 22 at the starting-up time of the oscillator. Therefore, the voltage amplification at a node 23 becomes the function of the amplitude of the voltage reference signal on the line at the starting-up time. The impedance of a varactor 14 is set to such a magnitude that can reliably start the oscillator. When the oscillator once starts oscillations, the selector 20 replaces the reference signal on the line 18 with a frequency control signal on a line 26 as the inputs to the amplifier 22 and node 23. Thereafter, the oscillation frequency of the oscillator is controlled by the amplitude of the frequency control signal selected by the user. An oscillation detecting circuit 28 detects the oscillation of a circuit and generates an output to instruct the selector 20 to input the voltage reference signal on the line 18 to the amplifier 22.;COPYRIGHT: (C)1996,JPO