Note: An avalanche transistor-based nanosecond pulse generator with 25 MHz repetition rate

Abstract

We have developed an avalanche transistor-based pulse generator for driving the photocathode of an image intensifier, which comprises a mainly capacitive load on the order of 100 pF. The circuit produces flat-top pulses with rise time of 2 ns, FWHM of 10 ns and amplitude of tens of V at a high repetition rate in the range of tens of MHz. The generator is built of identical avalanche transistor sections connected in parallel and triggered in a sequence, synchronized to a reference rf signal. The described circuit and mode of operation overcome the power dissipation limit of avalanche transistor generators and enable a significant increase of pulse repetition rates. Our approach is naturally suited for synchronized imaging applications at low light levels. The pulse repetition rate is another property of generators that plays an important role in some applications. High repetition rates of ≥20 MHz have been reported for circuits using vacuum tubes [3] and step recovery diodes [11]. One limiting factor in avalanche transistor circuits based on the basic triggered-switched capacitance-discharge topology [1] is the rate at which the energy storage element (lumped or distributed capacitance) at the collector can be recharged. Higher rates are achievable by replacing the charging resistor with a more complex passive [9] [12] or active circuit [10]. Eventually, another limitation arises due to power dissipation in the transistors. It can be mitigated to some extent by heat-sinking, but the pulse rates are still practically limited to a few MHz in continuous operation [10].The circuit presented in this work (German patent application 10 2017 125 386.6 filed on 10/30/2017) (FIG 1) overcomes both the recharging and dissipation limits. It is based on multiple avalanche transistor sections connected in parallel to the same load and triggered sequentially. A similar principle for increasing the pulse repetition rate of thyratron-based generators has been demonstrated [13], but without the provisions for synchronization detailed in our work. The pulse generator is designed for a specific application: driving the photocathode of a fast-gating image intensifier [14] for synchronized imaging of the ion micromotion in an rf trap [15] at a frequency of about f=25 MHz. Micromotion is a generally unwanted driven oscillation which occurs whenever a trapped ion is displaced from the rf node. We determine its amplitude via the photon-correlation technique, which makes use of the fluorescence modulation due to the 1st-order Doppler effect on a strongly allowed optical transition [16], [17].

Probing Time Dilation in Coulomb Crystals in a High-Precision Ion Trap

“…Details on the electronic circuit can be found in Ref. [43]. Photoelectrons are subsequently multiplied using a multichannel plate assembly and converted back to photons by acceleration onto a fluorescent screen.…”

“…We perform this calibration using the long-term stable axial micromotion amplitude of a single ion, as determined in PMT measurements before and after, as a reference (see Ref. [43]). The evaluation according to [38] yields a micromotion modulation index β i = k i r emm , where r emm is the micromotion amplitude and k the laser wave vector.…”

Cross-Hole GPR for Soil Moisture Estimation Using Deep Learning

“…The pulse based radars are implemented efficiently using ultra wide band principles for pulse generation. The design of pulse-based radars is based on avalanche transistors [22], tunneling diodes [23], nonlinear transmission lines [24], and step recovery diodes [25].…”

Design of an ultra‐wideband picosecond pulse generator based on step recovery diodes with an improved SPICE model

“…An ultra-wideband (UWB) narrow-width pulse generator is a critical component of short-range wireless communication technologies, ultra-wideband radar detection systems, 1 wideband sampling circuits, and real-time analog signal processing (R-ASP) technology. 2 A variety of architectures, including avalanche transistors, 3 field-effect transistors (FETs), 4,5 tunneling diodes (TDs), 6 nonlinear transmission lines (NLTLs), [7][8][9] and step recovery diodes, [10][11][12][13][14][15][16][17][18][19][20] have been experimentally demonstrated to generate a sub-nanosecond or even picosecond Gaussian pulse.…”