Ramp generator employing comparator circuit for maintaining constant starting voltages for different timing resistors

Claim 1

A RAMP VOLTAGE GENERATOR CIRCUIT, COMPRISING: A TIMING CAPACITOR; A PLURALITY OF TIMING RESISTORS HAVING DIFFERENT VALUES OF RESISTANCE; SWITCH MEANS FOR SELECTIVELY CONNECTING SAID TIMING RESISTORS IN SERIES WITH SAID TIMING CAPACITOR AND A SOURCE OF CURRENT; MEANS FOR REGULATING THE FLOW OF CURRENT THROUGH THE SELECTED TIMING RESISTOR TO PRODUCE A RAMP VOLTAGE ACROSS SAID CAPACITOR WHICH VARIES LINEARLY FROM A STARTING VOLTAGE; GATE MEANS WHICH IS NONCONDUCTING DURING THE PRODUCTION OF SAID RAMP VOLTAGE, AND WHICH IS RENDERED CONDUCTING TO RETURN SAID RAMP VOLTAGE TO SAID STARTING VOLTAGE AND TO CONDUCT CURRENT FLOWING THROUGH SAID SELECTED RESISTOR SO THAT SAID STARTING VOLTAGE TENDS TO VARY WITH THE RESISTANCE VALUES OF SAID RESISTORS; AND COMPARATOR MEANS RESPONSIVE TO A DIFFERENCE IN VOLTAGE BETWEEN SAID STARTING VOLTAGE AND A REFERENCE VOLTAGE FOR MAINTAINING SAID STARTING VOLTAGE SUBSTANTIALLY CONSTANT WHEN DIFFERENT TIMING RESISTORS ARE SELECTED BY SAID SWITCH MEANS.