Model 745T-4C Femtosecond Digital Delays with 5 Picosecond Jitter

Model 745T-4C Femtosecond Digital Delays with 5 Picosecond Jitter


Channels4 or 8 independent delay outputs
Range0 up to 20s
Resolution 1 ps
RMS Jitter25 ps + delay x 10e-8 (T0 to any output)
Accuracy< 250 ps + delay x 10e-8
Time Base50 ppm stability


Model 745T Datasheet




745T User Manual

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  • Description


Model 745T Femtosecond Digital Delays with 5 Picosecond Jitter

The Model 745T Digital Delay Generator (DDG) offers the world’s leading performance in a benchtop timing instrument. Twenty-five years ago, our Model 7095 Digital Delay Generator dramatically advanced research with jitter below 25 ps. Now, with all the features of a modern DDG, the Model 745T gives users incredible performance at a fraction of the cost. The Model 745T offers 4 precision delay channels from the front panel (output rise time less than 2 ns) with an additional 4-channel option on the rear panel (output rise time less than 5 ns). The Model 745T synchronizes to an external clock at 10 MHz or 80 MHz or custom frequency between 10MHz and 80MHz making the unit ideal for a broad range of applications that require short time domain delays.

The Clock In Connector and Clock Out Connector, are located on the rear panel of the instrument. A convenient Ethernet interface on the rear panel, allows remote control of the instrument. Berkeley Nucleonics’ DDG-MUC software controls up to eight instruments (64 Channels). Alternatively, you may use the LabVIEW driver or the embedded web interface for ease of set up and control. The control software and LabVIEW drivers are included with the Model 745T at no additional cost.

Because many industries are now moving away from locally installed software packages, we have embedded a control interface in the Model 745T instrument. This also allows all parameters to be controlled by any PC, Mac or Linux system with a web browser. All you have to do is to type in the unit’s IP address into the browser after connecting a cable from the Ethernet port to your computer or network. A USB port is also available if LAN port cannot be used. Ethernet ports allow the user to use the web interface or sends and receives SCPI commands while the USB is SCPI . This is ideal for laboratories where you may need to move the delay generator to different locations.



The Model 745T virtually eliminates triggering indeterminacy by having a clock that is now in phase with an External Trigger. The resulting external trigger jitter is far better than instruments whose outputs are synched to an internal free-running clock. See the datasheet for exact jitter specification and additional details on “Achieving 2 Picoseconds Jitter in a DDG”. The following chart indicates typical jitter at various delays:

  • Internal Trigger, Delays < 100ns: 2 picoseconds
  • Internal Trigger, Delays > 100ns: 15 picoseconds + timebase
  • External Trigger, Delays < 100ns: 25 picoseconds
  • External Trigger, Delays > 100ns: 25 picoseconds + timebase

Back of Model 745T


The Model 745T Digital Delay Generator offers users several options for triggering timing channels: External, Internal, and Remotely (Remote trigger: only asynchronous Single-Shot). Externally trigger on the positive or negative slope of your trigger signal and select a level from 0.lV to 5.0V. Two internal trigger generators are adjustable from 0.25 Hz to 1 MHz in 1 Hz increments (note: it’s possible to set the period by step of 5ns as well, the range is then 1µs to 4s by step of 5ns). These internal rep rate generators may be started by front panel pushbutton or remotely via your software interface. Either trigger mode may be set as one-shot or repetitive.

BURST MODE, for instance: pulse number 2 to 2^16-1, period 1000ns to 1s (depending on the trigger rate)

TRIGGER PRESCALER, for instance: prescaler value applied to the external trigger goes from 1 to 2^16-1

GATE MODE, for instance: can be set to General or individual channel

*See the user manual for more details.


The Model 745T Digital Delay Generator is housed in a compact design. The packaging dimensions are of 8.5″ X 9.6″ x 5.3″. The convenient design allows two instruments (up to 16 channels) to fit side-by-side in a 19″ rack mount (sold separately). This small footprint allows for many channels packed into a small space on a bench or in a rack system. Berkeley Nucleonics offers a variety of custom packaging options as well. For even tighter space constraints, ask about a cPCI card-level version of the Model 745T or a custom enclosure design. Multi-instrument applications may find that operating from a single master clock may be useful. The standard benchtop package can be mounted with one or two instruments in a 19″ rack.


On the front panel there are four standard Outputs, one external Trigger Input, and one Gate Input. Optionally, four more Outputs can be available on the front panel as well (total eight channel outputs) On the rear panel, there are Clock In, Clock Out, T0, and Auxiliary connectors.


Model NumberDescription
745T-4CStandard Touchscreen Model, 4 High Precision Channels
745T-8CStandard Touchscreen Model, 4 High Precision Channels, 4 Standard Channels

Add On Module / Options

Model NumberDescription
745-RMRack Mount System. Accommodates one or two Model 745T units
GFT101Electrical to Optical Converter - Takes a 2.5V to 10V input and produces a 1310nm output with 1 ns Risetime and 30ps RMS jitter. The convertor connects to the front panel of the Pulse/Digital Delay Generator. The optical pulse is appx 0.3mW and allows long range transmission in remote locations.
GFT500200ps Fast Rise Time Step Generator Module - This device provides fast Step Pulses with <2ps RMS jitter and amplitudes from 4V to 9V, settable by the factory. Connectors are high speed SMA.
GFT200Optical to Fast Electrical Pulse of 10 volts under 50Ω - This unit takes 1310nm wavelength pulses at -15dBm or better, and converts them to 10V output pulses with 30ps RMS jitter. This unit enables long range transmission of timing signals.
GFT632High Voltage Module - Offers fast output pulse 32V amplitude under 50Ω, < 3ns rise time - This module is externally triggered and provides high voltage pulses with fast risetimes. The device can be up to 20 meters from your pulse generator so it is closer to the device being triggered. A 70V option is also available with widths of 1uS and risetime of 1.2 nanoseconds.
GFT400Narrow Pulse Module - Achieve 2V into 50 Ω with narrow 500ps wide pulses. Jitter is <5ps RMS and the module operates on standard 12V AC/DC adapters. Input signals can be as low as 1.5V and require a width of >10ns.


Rise times below 1 nanosecond and Pulse Widths down to 10 nanoseconds are achieved by Channel Grouping. In this example, we group Channel 1 + Channel 2. The jitter is below 5 picoseconds and the delay and width resolution are both 250 femtoseconds. Contact the customer support for special output requirements. Available with GFT400 Module.


Channels4 or 8 independent delay outputs
Range0 up to 20s
Resolution 1 ps
RMS Jitter25 ps + delay x 10e-8 (T0 to any output)
Accuracy< 250 ps + delay x 10e-8
Time Base50 ppm stability


InternalTwo Timers, F= 0.25 Hz to 1 MHz
External1 trigger inputSoftware Asynchronous single shot

Output T0 5 V / >50 Ω, 100ns to 10µs

Posititve or negative slope

Minimum trigger delay < 65 ns

ControlFront Panel or Remote via Ethernet or USB


Amplitude2 V to 5 V / 50 Ω
Rise/Fall time< 2 ns / <2 ns
Width100 ns to 10µs
Clock InputStandard 10 MHz and 80 MHz     *ask factory for custom clock frequency


Interface ControlFront panel, Ethernet/Internet (Webpage)
SoftwareFree Drivers for Win7
SizeRack 19", 2U, D= 300mm
Power90 to 220 VAC / 0.5 A
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