Patent attributes
A first bias circuit outputs a first direct-current voltage to charge a first capacitor based on a clock signal. A second bias that outputs a second direct-current voltage to charge a second capacitor based on a clock signal. A first MOS transistor has a gate and a source. The first direct-current voltage is applied between the gate and the source of the first MOS transistor to bias the gate of the first MOS transistor. A second MOS transistor has a gate and a source, and a drain connected to the source of the first MOS transistor. The second direct-current voltage is applied between the gate and the source of the second MOS transistor to bias the gate of the second MOS transistor. A coupling capacitor has a first end connected to the source of the first MOS transistor, and a second end to which an alternating-current signal is input.