Voltage regulator circuitry is provided that produces a stable programming-voltage on a programmable integrated circuit. The programmable integrated circuit has programming control circuitry that provides logic-level programming signals. A controllable voltage supply increases the strength of the logic-level programming signals to produce programming-voltage-level programming signals. The programming-voltage-level programming signals are used to program programmable elements such as flash transistors on the programmable integrated circuit. A temperature-insensitive diode-based voltage feedback circuit is connected to the output of the controllable voltage supply. The voltage feedback circuit provides a corresponding feedback voltage to the controllable voltage supply that the controllable voltage supply used to stabilize the magnitude of the programming-voltage-level programming signals.