A high-speed gated baseline restorer and its implementation in a blood cell volume analyser

Accurate measurement of the height of individual pulses in a signal that is a.c.-coupled is dependent upon correcting a changing baseline to a constant value. A new fast baseline restorer, using internally triggered gated feedback with gain, has been designed and a version optimized for Gaussian-shaped pulses. Performance is dependent on the magnitudes of both the forward and the feedback gains. The design presented can achieve a 0.5% accuracy in pulse height for a minimum pulse width of 2.5 microseconds or for 5 microseconds overlapping pulses as long as the overlap is less than 50%. Typical applications for the baseline restorer include blood cell volume measurement systems, scintillation counters and radiation spectroscopy.