Abstract: In a photomultiplier tube (PMT) device having a plurality of dynodes provided between a cathode and an anode, a cancellation circuit provides two different modulation signals to the PMT to cancel the effects of the modulation signals upon the output of the PMT. For one embodiment, a cancellation circuit includes an input to receive an input modulation signal, a first output to provide a first output modulation signal to a first dynode, and a second output to provide a second output modulation signal to a second dynode, wherein the first and second output modulation signals are 180 degrees out-of-phase. For another embodiment, the cancellation circuit provides the input modulation signal to one of the PMT's dynodes, and also subtracts the input modulation signal from the PMT's output signal.