Power supply device and image forming apparatus

A power supply device which generates a bias voltage in which an AC voltage and a DC voltage are superimposed and applies the bias voltage to a voltage application target included in an image forming apparatus, comprising:

• an AC voltage output circuit which outputs the AC voltage;
• and
• a DC voltage output circuit which generates a DC voltage corresponding to the voltage application target, wherein
• the DC voltage output circuit includes
• a first voltage dividing resistor provided between a power supply line of a voltage output portion and a ground potential,
• a second voltage dividing resistor provided between the first voltage dividing resistor and the ground potential,
• a capacitor provided in parallel with the second voltage dividing resistor, and
• an operational amplifier which outputs a voltage that has been amplified based on a partial voltage divided by the first voltage dividing resistor from the power supply line,
• an output of the AC voltage output circuit is connected to the voltage output portion of the DC voltage output circuit, and
• a cutoff frequency of a low-pass filter circuit constituted of the first voltage dividing resistor, the second voltage dividing resistor, and the capacitor is set to be lower than a frequency of the AC voltage output from the AC voltage output circuit.