A peak detector circuit includes a first capacitor coupled to an inverter and a first switch in parallel with the inverter. An input of the inverter couples to second and third switches. The second switch couples to an input voltage node. The third switch couples to an output voltage node of the peak detector circuit. The peak detector circuit includes a second capacitor coupled to the third switch and a third capacitor coupled to the second capacitor by way of a fourth switch. The third capacitor couples via a fifth switch to a power supply voltage node or a ground. A periodic control signal causes the first, second, and third switches to repeatedly open and close and a second control signal causes the fourth and fifth switches to open and close to adjust an output voltage on the output voltage node towards an input voltage on the input voltage node.