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DG645Digital Delay/Pulse Generator

DG645Digital Delay/Pulse Generator
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Digital Delay/Pulse Generator DG645 — Digital delay and pulse generator (4 or 8 channels) DG645 Digital Delay/Pulse Generator · 4 pulse, 8 delay outputs (opt.) · <25 ps rms jitter · Trigger rates to 10 MHz · Precision rate generator · Easy synchronization with 80 MHz mode locked lasers · Fast transition times · Ovenized crystal or Rb timebase (opt.) · Ethernet, GPIB and RS-232 interfaces The DG645 is a versatile digital delay/pulse generator that provides precisely defined pulses at repetition rates up to 10 MHz. The instrument offers several improvements over older designs — lower jitter, higher accuracy, faster trigger rates, and more outputs. The DG645 also has Ethernet, GPIB and RS-232 interfaces for computer or network control of the instrument. Delay Generator Timing All digital delay generators measure time intervals by counting cycles of a fast clock (typically 100 MHz). Most digital delay generators also have short programmable analog delays to achieve time intervals with finer resolution than the clock period. Unfortunately, one clock cycle of timing indeterminacy (typically 10 ns) can occur if the trigger is not in phase with the clock. The DG645 eliminates timing indeterminacy by measuring the timing of triggers with respect to the internal clock and compensating the analog delays. This approach reduces the jitter by about 100× and allows the internal rate generator to operate at any rate — not just a sub-multiple of the clock frequency. Triggering Stanford Research Systems The DG645 has many trigger modes. An internal rate generator, with less than 100 ps period jitter, may be set

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DG645 Digital Delay/Pulse Generator File Control Setup Measure Analyze Utilities Help 2:25 PM Combinatorial outputs showing 3 ns, 5 ns and 10 ns pulses with 1 ns transition times (5ns/div) and output offsets can range over ±2 VDC to source virtually any logic level (NIM, ECL, PECL, CMOS, etc.). Output transition times are less than 2 ns at any output amplitude. Rear-Panel Outputs Optional rear-panel outputs are available to support diverse applications. Option 01 provides a T0 output and eight logic levels, with transition times less than 1 ns. Option 02 provides these same outputs but as...

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DG645 Digital Delay/Pulse Generator Ideal External Timebase Jitter vs. programmed delay Timebases The standard time base has an accuracy of 5 ppm, and a jitter of 10–8, which is suitable for many applications. Optional timebases are available for users who require better rate and delay accuracy or reduced rate and delay jitter. The timing error for a 1 s delay can be as large as 5 µs for the standard timebase, 200 ns for the OCXO timebase, but is only 500 ps for the rubidium timebase (all 1 year after calibration.) DG645 (cover removed) with optional Rb timebase. Rear panel shows the...

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DG645 Digital Delay/Pulse Generator More About the Outputs A timing cycle is initiated by an internal or external trigger. The T0 output, whose leading edge is the zero-time reference, is asserted 85 ns after the trigger. The delay settings (A, B, C, D, E, F, G and H) determine the timing of the front-panel and rear-panel outputs. The front-panel outputs have adjustable amplitude, offset, and polarity (non-inverted or inverted). Opt. 02 rear-panel outputs (30 V) Front-panel outputs (adjustable) Option 01 rear-panel outputs provide T0 and eight delay outputs (A, B, C, D, E, F, G and H) to...

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Channels 4 independent pulses controlled in position and width. 8 delay channels available as an option (see Output Options). Range 0 to 2000 s Resolution 5 ps Accuracy 1 ns + (timebase error × delay) Jitter (rms) Ext. trig. to any output 25 ps + (timebase jitter × delay) T0 to any output 15 ps + (timebase jitter × delay) Trigger delay 85 ns (ext. trig. to T0 output) Computer interfaces GPIB (IEEE-488.2), RS-232, and Ethernet. All instrument functions can be controlled through the interfaces. Non-volatile memory Nine sets of instrument configurations can be stored and recalled. Power <100...

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