CPC G06F 1/08 (2013.01) [G06F 1/10 (2013.01); G06F 1/12 (2013.01)] | 23 Claims |
1. An integrated circuit device (IC) having functional circuitry driven by a clock signal, the IC comprising onboard clock generation circuitry, the onboard clock generation circuitry comprising:
an input configured to accept a frequency reference signal;
at least one variable loading capacitor coupled to the input for converting the frequency reference signal into a calibrated clock signal;
calibration circuitry configured to calibrate the at least one variable loading capacitor based on a reference voltage, the calibration circuitry including:
a source of constant reference voltage,
a source of constant current, and
a pair of complementary switches coupled to the constant current source and to a variable reference capacitor, the complementary switches configured to be clocked according to the frequency reference signal to act as a resistor to convert the constant current to a derived voltage that charges a selected variable capacitor; and
trimming circuitry configured to convert the derived voltage into the calibrated clock signal.
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