Pulse height analyser
A pulse height analyzer for determination of the pulse height distribution of electronic pulses includes a set of comparators with a common input for analogue to digital conversion of the electronic pulses, a set of latches wherein the inputs of the latches are connected to the outputs of respective comparators for recording passage of the corresponding threshold voltages by the rising edge of a pulse, a priority encoder connected to the latch outputs for determination of a pulse height category consisting of pulses with a pulse height within a pulse height interval defined by respective threshold voltages, and a micro controller that is adapted to count the number of pulses within each pulse height category.
1. A pulse height analyzer for determination of pulse height distribution of electronic pulses, comprising:
a set of comparators provided with a common input, for analog to digital conversion of the electronic pulses into converted pulses,
a set of latches wherein inputs of the latches are connected to outputs of respective comparators for recording passage of corresponding threshold voltages by rising edges of the converted pulses,
a priority encoder connected to outputs of the latches for determination of pulse height categories consisting of converted pulses with a pulse height within pulse height intervals defined by the corresponding threshold voltages,
a micro controller that is adapted to count a number of pulses within each of the pulse height categories, and
a current source for connection to electrodes contacting an electrolyte in two chambers mutually connected by an orifice for Coulter counting of particles, wherein the threshold voltages of the comparators are dependent on an actual value of generated electrode current, and whereby possible variations of the electrode current are substantially cancelled by corresponding variations of the voltage thresholds.
2. A pulse height analyzer according to claim 1 , wherein the current source is a constant current source.
3. A pulse height analyzer according to claim 1 , further comprising a filter for filtering the electronic pulses to provide filtered pulses having a substantially constant delay from pulse start to maximum pulse amplitude, and for providing the filtered pulses as the common input of the comparators.
4. A pulse height analyzer according to claim 1 , further comprising a filter for filtering the electronic pulses to provide an output signal containing filtered pulses with a DC-value substantially equal to zero.
5. A pulse height analyzer according to claim 1 , further comprising a plurality of sets of comparators for pulse height determination of input electronic pulses of different amplification.
6. A pulse height analyzer according to claim 1 , further comprising circuitry for resetting the latches a predetermined time period after start of a converted pulse, the time period being independent of the pulse height and pulse width.
7. An integrated circuit comprising the pulse height analyzer according to claim 1 .
8. A field programmable gate array comprising the pulse height analyzer according to claim 1 .
9. An application specific integrated circuit comprising the pulse height analyzer according to claim 1 .