US Patent 10128747 Frequency-controlled voltage source

Voltage source circuits, asynchronous processing systems and methods are disclosed. A voltage source circuit includes a capacitor storing an operating voltage for an asynchronous processor. A frequency comparator compares a frequency reference and a feedback signal indicative of an operating frequency of the asynchronous processor to determine whether or not the operating frequency is less than a target frequency. When operating frequency is less than the target frequency, a charge pump adds charge to the capacitor.