OSCILLATOR CIRCUIT, SEMICONDUCTOR DEVICE AND SEMICONDUCTOR MEMORY DEVICE PROVIDED WITH THE OSCILLATOR CIRCUIT, AND CONTROL METHOD OF THE OSCILLATOR CIRCUIT

摘要

There is provided an oscillator circuit in which an oscillation permitting signal (EN) sets an oscillator section (5) in an oscillation-operable state, whereby a controller section (4) starts operation. The controller section (4) that has started its operation changes an oscillation-frequency control signal (VR) value corresponding to a predetermined oscillation frequency so as to set an oscillation frequency at an oscillator section (5). Further on, the oscillator section (5) outputs an oscillation signal (VOSC) in response to a detection signal (MON) that is outputted after a detector section (1) compares a signal inputted therein with a predetermined signal value and detects that the inputted signal reaches a predetermined signal value. Thereby, a transient state of an oscillation-frequency control signal (VR) can be detected. That is, there can be avoided an output of an unstable oscillation signal due to a transient oscillation-frequency control signal (VR). Such an oscillator circuit is capable of obtaining stable frequency by avoiding output having unstable frequency that is likely to occur to an operation/stop-control-feasible type oscillator circuit when oscillation begins. IMAGE