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4GHz time-to-digital converter (TDC)

Kore is pleased to announce our new 4GHz time-to-digital converter (TDC) product for 2010. This timing unit with 250ps capability is the product of a three year development programme and replaces our older 2ns TDC. The new TDC will feature in all future Kore products for time-of-flight mass spectrometry.

As with our previous 2ns TDC, we are offering our new TDC as a stand-alone product for researchers who are building their own TOF experiments and who are looking to configure their equipment with a high performance timing unit.

We also offer to bundle the TDC with a data acquisition computer running GRAMS/AI - a general spectroscopy program from Thermo Galactic 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.

4GHz Time-to-Digital Converter (TDC)

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Introduction

The Kore 4GHz time-to-digital converter (TDC) is new for 2010 and is a compact, bench-top timing unit designed to record a fast stream of event times relative to a single start event (at time=0). 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.

This product on its own, without the data acquisition system and software, is suited to engineers with experience of integrating instrument systems. Users with little or no programming experience are advised to ask Kore about the extended data package with a Kore data acquisition computer, GRAMS /AI and Kore TOF acquisition software.

Key Features

Detailed TDC Specification

Deliverables

Note 1: The data collection utilities are launched from the command line with parameters taken from a simple text file. They can be used for collecting time histograms, collecting time-stamp list-files and monitoring count-rates within a pair of regions of interest for diagnostic purposes. They display windows during execution to show experiment progress. A complete data system might have in addition (a) a graphical user interface to assist in selecting experimental parameters (b) software to process the data and display the result in the form of plots or images. These facilities can be added by the user; the utilities have been designed to make this as easy as possible. Alternatively, the optional Grams/AI and extensions may be purchased.

4GHz Time-to-Digital Converter (TDC) and Time-of-Flight Mass Spectrometry Data Acquisition System

photo   photo

Introduction

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.

The Kore 4GHz time-to-digital converter (TDC) is new for 2010, and is a compact, bench-top timing unit designed to record a fast stream of event times relative to a single start event (at time=0). 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.

GRAMS/AI from Thermo Galactic 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.

A researcher would use the TDC's start signal to trigger various units in the apparatus, and would take the detector output signal to the TDC signal input. The researcher would then have 250ps timing accuracy up to 4.2ms (maximum cycle length) combined with full data acquisition and replotting facilities.

Key Features

Detailed TDC Specification

Key Features of GRAMS/AI and Kore Mass Spectral Extensions

Deliverables

Note 2: The data collection utilities are launched from the command line with parameters taken from a simple text file. They can be used for collecting time histograms, collecting time-stamp list-files and monitoring count- rates within a pair of regions of interest for diagnostic purposes. They display windows during execution to show experiment progress. A complete data system might have in addition (a) a graphical user interface to assist in selecting experimental parameters (b) software to process the data and display the result in the form of plots or images. These facilities can be added by the user; the utilities have been designed to make this as easy as possible. Alternatively, the optional Grams/AI and extensions may be purchased.

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4GHz time-to-digital converter (TDC) specifications

Timing resolution 0.25ns
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 1)
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

Note 1: Using the standard motherboard-based USB interface on an inexpensive general purpose PC purchased early 2009 [Pentium E5300 Dual Core 2.6 GHz with 1G RAM running WinXP svpk3. Device manager reports hub as "Intel 82801G (ICH7 Family) USB2 Enhanced Host Controller - 27CC"]

Note 2: A measurement was made of the pulse width from a digital oscilloscope 'Cal' output, presumably crystal controlled, but no specification was available for pulse-width jitter. The TDC was triggered on each cycle by the leading edge of the pulse and the trailing edge was interpreted as a stop value. The histogram from a 1 hour measurement was fitted with a Gaussian curve, which had a full width half maximum of 470 ps. The leading edge will be subject to 250 ps of jitter because the 'scope is not synchronised to the TDC. This element of the jitter would be absent in an experiment using internal cycle trigger. For estimation purposes it was assumed that the 'scope and intrinsic TDC jitter were of similar size (both crystal controlled clocks) and that the various elements combined in quadrature (sum equals square-root of sum of squares).

Note 3: The input comparator has protection diodes that limit the differential input voltage. This means as the difference between the input and the threshold exceeds about 1.25V a little more current will be drawn. This causes no damage but may give rise to double pulsing under some circumstances.

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Last updated: 14:15 12/03/2014

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