Abstract: An adaptive sampling circuit of the power converter according to the present invention comprises a sample-and-hold unit and a signal-generation circuit. The sample-and-hold unit is coupled to a transformer to generate a feedback signal by sampling a demagnetized voltage of the transformer in response to a sample signal. The signal-generation circuit generates the sample signal in response to a magnetized voltage of the transformer, the demagnetized voltage of the transformer, a switching signal and a code. The sample signal is used for sampling the demagnetized voltage. The feedback signal is correlated to an output voltage of the power converter. The switching signal is generated in response to the feedback signal for switching the transformer and regulating the output of the power converter. The adaptive sampling circuit is used to precisely measure the demagnetized voltage of the transformer without the limitation of the transformer design.

Abstract: A multiplier-divider circuit for signal process according to the present invention comprises a digital-to-analog converter, a first counter, a second counter, an oscillation circuit, and a control-logic apparatus. The digital-to-analog converter generates an output signal of the multiplier-divider circuit in accordance with the value of an input signal and a first signal. The first counter generates the first signal in response to a clock signal and the duty cycle of the input signal. The second counter generates a second signal in response to the clock signal and the period of the input signal. The oscillation circuit generates the clock signal in accordance with a third signal. The control-logic apparatus generates the third signal in response to the second signal and a constant. The first signal is correlated to the duty cycle of the input signal. The second signal is correlated to the period of the input signal.