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Digital Delay / Pulse Generator

Digital Delay / Pulse Generator
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· 4 pulse, 8 delay outputs (opt.) · 25ps rms jitter · Trigger rates to 10MHz · 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 · DG645 ... $3995 (U.S. list) Stanford Research Systems phone: (408)744-9040 www.thinkSRS.com The DG645 is a versatile digital delay/pulse generator that provides precisely defined pulses at repetition rates up to 10MHz. 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 The DG645 has many trigger modes. An internal rate generator, with less than 100 ps period jitter, may be set from DG645 Digital Delay/Pulse Generator Digital Delay/Pulse Generator DG645 . Digital delay and pulse generator (4 or 8 channels) www.thinkSRS.com

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DG645 Digital Delay/Pulse Generator Stanford Research Systems phone: (408)744-9040 www.thinkSRS.com 100 ìHz to 10 MHz with 1 ìHz resolution. An external trigger input, with adjustable threshold and slope, can trigger a timing cycle, a burst of cycles, or a single shot. A single shot can be triggered with a key press. A line trigger operates synchronously with the AC mains. A rear-panel trigger inhibit input can disable the trigger or any of the pulse outputs during a timing cycle. The DG645 supports a number of complex triggering requirements via a trigger holdoff and prescaling feature....

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The timing error for a 1 s delay can be as large as 5 ìs for the standard timebase, 200 ns for the OCXO timebase, but is only 500 ps for the rubidium timebase (all 1 year after calibration.) For short delays the jitter is typically 20 ps. However, for a 1 s delay, the standard timebase can contribute up to 10 ns of jitter, while the optional timebases contribute less than 10 ps of additional jitter. Fast Rise Time Module The DG645 front-panel outputs have transition times of less than 2 ns. The SRD1 is an accessory, built into an in-line BNC connector, which reduces the rise time of a...

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Stanford Research Systems phone: (408)744-9040 www.thinkSRS.com 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). Option 1 rear-panel outputs provide T0 and eight delay outputs (A, B, C, D, E, F, G and H) to allow...

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DG645 Specifications Stanford Research Systems phone: (408)744-9040 www.thinkSRS.com Delays 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) Timebases External input 10 MHz ± 10 ppm, sine >0.5 Vpp, 1 kÙ impedance Output 10 MHz, 2 Vpp sine into 50 Ù External Trigger Rate DC to...

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