| 摘要 |
A voltage feed-forward circuit, multiplier using the voltage feed-forward circuit, and power factor correction (PFC) circuit using the multiplier; the voltage feed-forward circuit is used to maintain and output a peak voltage (Vff) of an input voltage (Vin), and comprises a first switch element (S1), a logic control unit (U1), a second switch element (S2), a first capacitor (C1), a third switch element (S3) and a second capacitor (C2); a first end of the first switch element (S1) is connected to a supply voltage (Vcc), and a control end conducts in response to a first control signal (Φ1); the logic control unit (U1) is used to output a second control signal (Φ2) during the peak voltage of the input voltage (Vin) and output a third control signal (Φ3) during a non-peak voltage of the input voltage (Vin); a first end of the first capacitor (C1) is grounded; a first end of the second switch element (S2) is connected to a second end of the first switch element (S1), and a second end thereof is connected to a second end of the first capacitor (C1), and a control end thereof causes the second switch element (S2) to conduct in response to the second control signal (Φ2); a first end of the third switch element (S3) is connected to the second end of the first capacitor (C1), and a control end thereof causes the third switch element (S3) to conduct in response to the third control signal (Φ3); a first end of the second capacitor (C2) is grounded, and a second end thereof is connected to the second end of the third switch element (S3) and outputs the peak voltage (Vff) of the input voltage (Vin) maintained by the second end of the second capacitor (C2); and the first control signal (Φ1) and the second control signal (Φ2) begin to be provided at the same time, and the first control signal (Φ1) stops being provided when a voltage of the second end of the first capacitor (C1) is greater than the peak voltage (Vff) of the input voltage (Vin). The voltage feed-forward circuit, the multiplier and the PFC circuit facilitate increased stability of the PFC circuit and an improved response speed to the input voltage as well as an improvement of linearity and output current precision of the multiplier. |
