| 摘要 |
A ramp generator comprises an integrating capacitor and a current source connected to the capacitor to charge the capacitor and thereby generate a ramp signal. A switching device is connected to the capacitor and is operative to discharge the capacitor periodically in response to a periodic control signal applied to a control terminal of the switching device. A comparator has a first input terminal connected to a peak detector, which detects the peak value of the ramp signal, and a second input terminal connected to receive a reference voltage. The comparator compares the peak value of the ramp signal and the reference voltage and is connected to the current source to control the rate of supply of current to the capacitor in response to the comparison result so as to maintain a predetermined relationship between the amplitude of the ramp signal and the reference voltage, independently of the frequency of the control signal.
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