Delay circuit using capacitor as delay element

摘要

A delay circuit using a capacitor with an MOS structure as a delay component, includes a clamp circuit operating a clamp operation and a clamp release operation in response to levels of an input signal, the clamp circuit clamping a voltage applied to the capacitor to a specified charging initiation voltage during the clamp operation; a charging circuit charging the capacitor with a constant current when the clamp operation is released; and a delayed signal producing circuit producing a delayed signal when the voltage of the capacitor being charged reaches a voltage of a predetermined value.

主权项

1. A delay circuit comprising:
a capacitor as a delay component; a clamp circuit having a first MOSFET connected to the capacitor and operating a clamp operation and a clamp release operation in response to levels of an input signal, the clamp circuit clamping a voltage applied to the capacitor to a predetermined charging initiation voltage at the clamp operation; a charging circuit having a first constant current source connected to the capacitor and charging the capacitor with a first constant current when the clamp operation is released; and a delayed signal producing circuit having a second MOSFET connected to the capacitor and becoming a conduction state when the voltage of the capacitor being charged reaches a voltage of a predetermined value, and a second constant current source connected to the second MOSFET; when the second MOSFET becomes conduction, producing a delayed signal with a voltage changed by the conduction at a connection point of the second MOSFET and the second constant current source; and simultaneously discharging from the capacitor a second constant current of the second constant current source to decrease a charging speed of the capacitor.