Generation of narrow impulses for TDR Application

[uditha]

Hi,

I'm trying to find a circuit topology for generating fast impulses for a TDR application. The requirement is to generate pulses with about 3.5 V peak amplitude onto a 50 Ω line with pulse widths in the order of 350 ps.

I would be very much grateful if you could shed some light into some circuit topologies I may look into. Also what is the best approach to simulate this sort of circuit?

Thanks in advance

 

[D.A.(Tony)Stewart]

Normally PECL gates can be configured to produce predictable fast impulses. Consider direct and inverted signal into an OR gate to achieve a pulse 0.8Vpp

Other methods might use a chain of FF's being clocked at 3GHz or ...
a 20GHz 6 bit DAC... or..
an ASIC with a step recovery diode (SRD)