Linear Voltage Regulator Stability Analysis through Phase Margin

Most linear voltage regulators require an output capacitor with specific value of internal parasitic element called equivalent series resistance (ESR). This ESR range must be characterized to ensure the stability of the voltage regulator is guaranteed. Instability of the linear voltage regulator such as indicated by excessive overshoot and undershoot of output voltage give negative effect on the electronic devices. Therefore, this study aims to investigate the range of ESR through phase margin measurement. LTspice simulation software was used to simulate a voltage regulator circuit, that contains an adjustable ESR as well as load. This software was also used to assist in the process of detailing the value of ESR and determining the output voltage stability through phase margin measurements. To conclude, this research able to identify the ESR range that need to be used to produce stable output voltage.