Provided here is a low noise 45V output APD bias circuit that provides 2.5mA of load current. The circuit uses noise suppression and filtering capacitors to keep the peak-to peak noise below 500μV or 0.01% ripple as a percentage of full-scale (5V). As the voltage at the APD pin increases, the output ripple increases as one would expect, but it still is well within the performance criteria of most APD circuits. The 0.1μF capacitor in parallel with the photodiode filters power supply switching noise. The small 10nF feed-forward capacitor between MONIN and FB reduces output variations caused by load steps and also improves transient response.