Precise Trigger and Voltage Tracking Delay Circuit
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
This article describes a method for maintaining proper delays between circuits with varying supply voltages through the utilization of a Schmitt trigger and a depletion device/capacitor network instead of a resistor/capacitor network in a delay stage. The circuit shown in the figure consists of two main sections: a Schmitt trigger (T1, T2, T3 and T4) which fires at a preselected input voltage and a delay section (T5 and T6). Initially, nodes A and B are charged through devices T1 and T5 and the output is held at ground by T9. With a positive input signal on T3, node A discharges to ground through devices T2 and T3 when the input signal reaches the trigger point of the Schmitt trigger. The delay section (T5 and T6) takes over at this point, and node B starts to discharge through device T5 which is in saturation.