Constant fraction discriminator （CFD） is one of theoretic method which can locate timing point at same fraction of echo pulse in pulsed time-of-flight （TOF） laser rangefinding. In this paper, the theory of CFD met...Constant fraction discriminator （CFD） is one of theoretic method which can locate timing point at same fraction of echo pulse in pulsed time-of-flight （TOF） laser rangefinding. In this paper, the theory of CFD method was analyzed in reality condition. The design, simulation and printed-circuit-board （PCB） performance of CFD circuit were shown. Finally, an over amplified method was introduced, by which the influence of direct-current （DC） bias error could be reduced. The experimental results showed that timing discriminator could set the timing point to a certain point on echo pulse, which did not depend on the amplitude of echo pulse.展开更多
Readout electronics is developed for a prototype time-of-flight(TOF) ion composition spectrometer for in situ measurement of the mass/charge distributions of major ion species from 200 to 100 ke V/e in space plasma.By...Readout electronics is developed for a prototype time-of-flight(TOF) ion composition spectrometer for in situ measurement of the mass/charge distributions of major ion species from 200 to 100 ke V/e in space plasma.By utilizing a constant fraction discriminator(CFD) and time-to-digital converter(TDC), challenging dynamic range measurements were performed with high time resolution and event rates. CFD was employed to discriminate the TOF signals from the micro-channel plate and channel electron multipliers. TDC based on the combination of counter and OR-gate delay chain was designed in a highreliability flash field programmable gate array. Owing to the non-uniformity of the delay chain, a correction algorithm based on integral nonlinearity compensation was implemented to reduce the time uncertainty. The test results showed that the electronics achieved a low timingerror of < 200 ps in the input range from 35 to 500 m V for the CFD, and a time resolution of ～550 ps with time uncertainty < 180 ps after correction and a time range of6.4 ls for the TDC. The TOF spectrum from an electron beam experiment of the impacting N_2 gas further indicated the good performance of this readout electronic.展开更多
基金This work was sponsored by the National Natural Science Foundation of China （Grant No. 40801123）.
文摘Constant fraction discriminator （CFD） is one of theoretic method which can locate timing point at same fraction of echo pulse in pulsed time-of-flight （TOF） laser rangefinding. In this paper, the theory of CFD method was analyzed in reality condition. The design, simulation and printed-circuit-board （PCB） performance of CFD circuit were shown. Finally, an over amplified method was introduced, by which the influence of direct-current （DC） bias error could be reduced. The experimental results showed that timing discriminator could set the timing point to a certain point on echo pulse, which did not depend on the amplitude of echo pulse.
基金supported by the National Key Scientific Instrument and Equipment Development Projects of the National Natural Science Foundation of China(No.41327802)China Mars Project
文摘Readout electronics is developed for a prototype time-of-flight(TOF) ion composition spectrometer for in situ measurement of the mass/charge distributions of major ion species from 200 to 100 ke V/e in space plasma.By utilizing a constant fraction discriminator(CFD) and time-to-digital converter(TDC), challenging dynamic range measurements were performed with high time resolution and event rates. CFD was employed to discriminate the TOF signals from the micro-channel plate and channel electron multipliers. TDC based on the combination of counter and OR-gate delay chain was designed in a highreliability flash field programmable gate array. Owing to the non-uniformity of the delay chain, a correction algorithm based on integral nonlinearity compensation was implemented to reduce the time uncertainty. The test results showed that the electronics achieved a low timingerror of < 200 ps in the input range from 35 to 500 m V for the CFD, and a time resolution of ～550 ps with time uncertainty < 180 ps after correction and a time range of6.4 ls for the TDC. The TOF spectrum from an electron beam experiment of the impacting N_2 gas further indicated the good performance of this readout electronic.
