| 摘要 |
The present invention is a constant current source whose magnitude is proportional to capacitor values, reference voltage and input frequency. A frequency divider provides a plurality of signals to one of a plurality of capacitor switches located within a charge generator. The outputs of the capacitor switches are combined to provide a known charge Qi to an output generator at regular intervals, t0=1/Fin. The output generator produces an output current Iout=Qi/t0=Ci*Vbg*Fin, where Ci is a capacitor value, Vbg is a reference voltage, and Fin is the input frequency. A controller provides a control signal to the output generator to limit variations in the output current Iout. The preferred embodiment may be used in conjunction with process invariant circuits in a variety of semiconductor technologies: CMOS, Bipolar, BiCMOS and GAS. In one embodiment, the present invention is used in conjuction with a timer/delay circuit. In another embodiment, the present invention is used in conjunction with a calibration circuit to compensate for various inaccuracies in component performance.
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