The 4GHz Time-to-Digital Converter
A high performance timing unit.
A high performance timing unit.
Our most advanced timing electronics yet, the Kore 4GHz time-to-digital converter (TDC) is a compact, bench-top timing unit designed to record a fast stream of event times relative to a single start event. It performs this task with a timing resolution of 0.25 ns with minimal dead time, high data rates and the ability to repeat the experiment at very high repetition rates. These features make the unit ideal for use in Time-of-Flight (TOF) mass spectrometry applications. In such an application, the unit issues or receives a cycle start signal at pre-set intervals and waits to receive timing pulses from an ion detector. The pulse times are recorded, buffered and streamed to the PC via a standard USB 2.0 serial interface. Here the standard driver software may process them to spectra ‘live’, or stream them to the hard disk for more flexible processing options.
We also offer to bundle the TDC with a data acquisition computer running GRAMS/AI™ – a general spectroscopy program from Thermo Scientific for which Kore has written time-of-flight mass spectrometry ‘extensions’. With this bundle, a user can add the ability to acquire and manipulate time-of-flight mass spectrometry data to their instrumentation, without needing to write their own data acquisition software.
|Number of hits per cycle||Unlimited|
|Maximum burst count rate||2 GHz|
|Full speed front end FIFO depth||8192 frames of 4ns|
|Maximum sustained count rate||>17,000,000 counts/s (Theoretical)|
|>4,000,000 counts/s (Measured)|
|Maximum time stamp value||0xFFFEFF ~4.2 millisec|
|Triggering modes||Fixed frequency free-running OR External Start trigger|
|Max cycle repetition rate||≥ 1MHz (hardware)|
|200 kHz (current software limit)|
|Min cycle repetition rate (free running)||≤20 Hz (hardware)|
|500 Hz (current software limit)|
|Min cycle repetition rate (External start trigger)||Unlimited|
|Number of cycles per experiment (on board counter)||1 to 4x109|
|Cycle counter reset time||<1µs|
|Dead time between cycles||36ns at cycle start and 4ns at end|
|Timing precision||<470ps (1 hour measurement of peak at 500µs) estimated as 280ps internal trigger & 380 ps external trigger 2 )|
|Start/Stop input range||-5V to +5V 3|
|Start/Stop input threshold range||-2.5V to +2.5V (positive or negative timing edges selectable in software)|
|Start/Stop input termination (jumper selectable)||50Ohm to ground (Normal) OR 50Ohm to -2V (ECL)|
|PC interface||USB 2.0|
|Power requirement (typical for board)||+5V 730mA and -5.2V 65mA|
|Bench-top case dimensions||280 x 300 x 70 mm|
|Bench-top power requirement||230/115 VAC 50/60Hz 7watt|
|Software requirement||Windows XP or later|
Our new 4GHz TDC can be purchased together with a data acquisition system running GRAMS/AI™ with Kore TOF Mass Spectral ‘extensions’. Such a package would be of use to researchers who are building TOF-MS apparatus or have existing equipment and would like to purchase a complete TOF data acquisition / data plotting system.
GRAMS/AI™ from Thermo Scientific is a general spectroscopy software suite. Kore has been using the GRAMS™ platform successfully for many years in its instrumentation, and has written what we term ‘mass spectral extensions’ specifically for the case of time-of- flight spectrometry.
Key Features of GRAMS/AI™ and Kore Mass Spectral Extensions:
A very fast digitiser, or analogue-to-digital converter (ADC), records the shape of the pulse waveform into memory. All the pulses resulting from a single spectrometer start event are recorded in a single trace; so in principle a complete mass spectrum can be recorded from one spectrometer cycle. However to achieve acceptable precision, it is often necessary to add a number of traces together to give an average.
The arrival time of each ion pulse is recorded as a simple number, or time-stamp, by a time-to-digital converter (TDC). The implicit assumption is that each pulse represents a single ion; all information about the shape of individual pulses is discarded. To create a mass spectrum, many spectrometer cycles are performed, typically a few thousand, and the time-stamps built into an arrival-time histogram.
The best strategy depends on the experiment, in particular on the number of ions expected in a single cycle and on any constraints to the cycle repetition rate e.g. a laser that won’t pulse faster than 10Hz.
Kore Technology is a centre of excellence in time-of-flight mass spectrometer technology and has a very strong R&D capability in terms of its personnel, all of whom have been heavily involved in a variety of analytical instrumentation development programmes.