Digital Delay/Pulse-Generator

ISA-Card: BME_G02
 
 

BME-G02f.gif
 
 


for precision Timing with low Jitter

Circuit Description

The BME_G02 is a PC-ISA card having 3 delay outputs that can produce delayed signals from 50nsec to 429sec, in steps of 25 picoseconds.

A trigger circuit starts the delay counters. There are 4 counters, T, A, B and an auxiliary counter. The T, A and B counters actually produce an output signal, while the auxiliary counter can only be used to produce an interrupt. In Edge-Mode the first level transition is determined by the programmed Delay - after the last Delay expired all outputs are reset together. In Gate-Mode the outputs A and B can be combined to form a gate signal, i.e. a rising(falling) edge after delay A has elapsed and a falling(rising) edge after delay B has elapsed, so you get an pulse with a variable(25ps resolution) pulse-width from 2ns to 429s.

The trigger can be produced internally by a modulo-N counter or by an external signal. The external trigger can by used as external clock, and can additionally can be gated and prescaled.
If more than 3 Outputs (or more than 1 Gate output) are needed, two ore more card's can be connected together via a ribbon-cable, resulting in 6 or more synchronous delayed outputs.


Specifications

Delays Delayrange 50ns - 429s (44bit)
  Delayresolution 25ps
  min. Dalaytime : 50ns (Insertion-Delay) (32bit * 100ns)
  Error :    <(1ns + 25ppm * delay)    )1
  RMS Jitter:      Output to Output: <(50ps + 10-8 * delay)       )1
Trigger to Output: <(250ps + 10-8 * delay)     ) only BME_SG02
Trigger to Output: <(50ns + 10-8 * delay)     ) BME_G03, BME_G05
Trigger External: Threshold Range: -2.5V to 2.5V in Steps of 1.2mV
    Slope :              rising or falling edge
    Input impedance : 10kW or 50W
  Internal: by a modulo-N counter running with the main clock
Outputs T0,A,B Mode : Slope or Gate (AB) output
  Load :  50W or 25W,
    T0 output can be configured for NIM output pulse
  Risetime :  <2ns for TTL 
<1.2ns for ECL or NIM (typical)
  Levels :  TTL:0 to 4V normal or inverted
    ECL: into -2.0 normal or inverted
    NIM
General Clock Source:  Internal: 10Mhz (80MHz) 25ppm        )1
    External: max. 250MHz with prescaler
  Interface :  PC ISA-bus    I/O adressable between 000 and 3F0 H
  Interrupts : can be fired with the finish of any of the delays T, A, B or after the auxiliary delay has elapsed.
    It is also possible to fire an interrupt with the main trigger of the delay generator(s), or after a fixed number of triggers has occurred.
    An Interrupt can be requested on lines int3 , int4,.... int7 of the PC XT/AT bus

 )1 Accuracy and Jitter depend on Clock Source (specs with 25ppm clock source)
     optional 1ppm clock source available


Options


  

  • BME_SG02:  Outputs synchronized to external trigger. 
                             All other functions as for BME_G02

  • BME_G03:  Delays individually resettable with a resolution of 100nsec. 
                            All other functions as for BME_G02

  • BME_G04:  Delays can be individually fired a second time after main trigger. 
                            All other functions as
      for BME_G03

  • BME_G05:  the ouputs can be vetoed with a modulo-counter 

Software


  

Application:    Laser Timing

Download pdf:      bme_g0x.pdf(159kB)


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