a transformer being controlled by a power switch the power switch is driven by a controller having a shaping circuit the shaping circuit uses a current generator switched resistor and capacitor to produce a reference voltage signal the controller drives the power switch based on the voltage reference signal resulting in a sinusoidal input current in a primary winding of the transformer resulting in high power factor and low total harmonic distortion for the converter application_number US 201615261340 A description fig7 shows a hi pf qr flyback converter 100 according to one embodiment of the present disclosure on the primary side the qr flyback converter 100 includes a controller 102 a bridge rectifier 104 having inputs 106 coupled to an ac power line that supplies an ac voltage v ac an input capacitor c in a voltage divider r a r b coupled to the bridge rectifier 104 a primary winding l p and an auxiliary winding l aux of a transformer 108 power switch m coupled to the transformer 108 and controlled by controller 102 sensing resistor r s coupled to the power switch m and controller 102 a resistor r zcd coupled to the auxiliary winding l aux and a clamp circuit 109 connected across the primary winding l p on the secondary side of the converter 100 a secondary winding l s of the transformer 108 has one end connected to a secondary ground and the other end connected to the anode of a diode d having the cathode connected to the positive plate of a capacitor c out that has.