A response of series regulator to incident high frequency noise on AC-mains

It is important in order to guarantee the stable operation of a digital circuit to understand the response of a power supply to incident high frequency noise. In this paper, the response of a series regulator to incident high frequency noise on AC-mains is analytically and experimentally clarified. As a result, it is shown that high frequency response of a series regulator is influenced by the parasitic capacitance between base and collector terminals of the control transistor, the parasitic capacitance between negative-input and output terminals of operational amplifier, and the output impedance of operational amplifier.