Location:Training / Power Supply / Low Noise, High Voltage DC/DC Converters / Low Noise, High Voltage DC/DC Converters

Kilovolt photomultipliers (PMTs), avalanche photodiodes (APDs), ultrasound transducers, condenser microphones, radiation detectors and similar devices with 100 microvolt noise require high voltage, low current biasing. In addition, the high voltage must be completely free of noise; typically noise is required to be well below 1mV, and sometimes noise is required to be as low as a few hundred μV. This video material details a circuit with 200V to 1000V output and less than 100μV output noise (measured over a 100MHz bandwidth). The above performance is achieved using special methods, most notably optimizing the power stage to minimize high frequency harmonic components. An additional aid for achieving low noise is that the load current rarely exceeds 5mA. This degree of freedom allows the use of output filtering methods that are not usually practical. Circuit noise measurements performed in the laboratory are demonstrated at the conclusion of the presentation.