Eight-Channel Fully Adjustable Pulse Generator

Abstract

This paper describes an eight-channel differential pulse generator based on a fast differential bipolar transistor output stage. It has been designed specifically to test new multichannel time-correlated single-photon counting (TCSPC) instruments, while maintaining a wide range of regulation possibilities in terms of frequency, amplitude, delay, and duty cycle. The input signal for each channel can be provided either by an on-board programmable frequency synthesizer or by an external reference shared by all channels. The chosen input is delivered to a delayer loop controlled by a field programmable gate array (FPGA), which provides the desired delay, minimizing the jitter contribution. The delayed signal is fed to an analog differential stage that provides the fast output, whose amplitude and offset are adjusted by a digital-to-analog converter, controlled by the FPGA. The experimental results on the instrument show an output slew rate of 1600 V/$mu text{s}$ over the complete full-scale range, which is between -2 and 6 V. The feedback delayer regulates the delay between 0 ns and 30 $mu text{s}$ whereas the high time is adjustable from a minimum of 10 ns to a maximum of 30 $mu text{s}$ . Finally, the frequency range is from 2 kHz to 50 MHz. All these adjustable parameters are managed by a microcontroller that works as an interface between the FPGAs and dedicated PC software. The implemented structure allows the system to achieve a time resolution down to 6 ps across all channels, making this instrument perfect for testing high time resolution TCSPC systems

Fast fully-integrated front-end circuit to overcome pile-up limits in time-correlated single photon counting with single photon avalanche diodes

“…A noninvasive way to estimate the duration of the reset transition consists in recording the distribution of events generated by a continuous illumination of the device, when the AQC is operated in gated mode [21,22]. To this purpose, we exploited a low-jitter pulse generator [23] to drive the Gate input of the AQC with a programmable square wave, so that it was possible to periodically force the active SPAD in hold-off and activate it for a fixed duration of 40 ns within each period; then we used a LED source to illuminate the active detector in a dark environment, ensuring that the average number of photons in a period was limited well below 0.1, to avoid pile-up distortion. A commercial TCSPC module (Becker&Hickl SPC-130) allowed us to collect recorded events in a histogram, depending on their arrival time within the Gate period.…”

5 ps Jitter Programmable Time Interval/Frequency Generator

“…Programmable arrays can be used either as a complete platform that performs timing generation [3,15,16,18] or just as a part of generator [13,14,17,19,20]. FPGA buildin DLLs and PLLs greatly facilitate TIG integration in a single chip but, so far, cannot generate as low-jitter TIs as those using external modules, e.g.…”

An FPGA-Based Hardware Platform for the Control of Spin-Based Quantum Systems

“…The control signal generation and output signal readout are required in spin-based quantum systems. Arbitrary waveform generators (AWGs) [13], [14] are usually utilized to generate radio frequency (RF)/microwave (MW) signals for controlling the spin-based quantum state [15], [16], and pulse/sequence generators are applied to obtain precise timing and synchronization [17], [18]. Amplitude and time measurements for the output signal are commonly realized with analog-todigital converters (ADCs) [19] and time-to-digital converters (TDCs) [20], [21].…”