| 摘要 |
Figure 3 is an exemplary embodiment of a free running oscillator (310) that is calibrated, the calibration circuit includes the reference oscillator (320), calibration control circuit (330), programmable look-up table (340), transistor (350), capacitor (360), and PWM circuit (370). The invention adjusts a capacitance value by pulse width modulating a control voltage for a switch in series with a capacitor. The PWM signal can be adjusted by using entry values found in a look up table, by using analog or digital control signals, or other approppate methods. The capacitance value tunes a frequency response or characteristic of an electronic circuit The response can be made to be insensitive to conditions such as temperature, power supply voltage or processing.
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