[Q] pulse generaton with a carrier

What are you using for the modulator (multiplier)? A double-balanced modulator should suppress the carrier 40 to 60 dB between the 10ns bursts, and will probably improve the 400MHz waveform.

Don

I was using a frequency mixer from Minicircuits. Its model number is ZAD-1-1.

LO/RF input freq. : 0.1-500MHz IF input freq. : DC-500MHz

If possible, would you please recommend any company that sells the double balanced modulator ?

D> On 9/12/05 8:42 PM, in article

Before you try a different mixer, it would be a good idea to check the voltage ratio of the 400 MHz RF input to the 10 nS pulse, which I'm guessing you are applying to the IF port. Since the pulse is the "LO signal" it should be about ten times the amplitude of the 400 MHz signal. If correction is not needed or does not improve the output signal, then another mixer will help.

The ZX05 family of double balanced mixers looks good. Be sure to choose by first matching the required LO signal to your pulse generator capability.

Realize that I'm shooting in the dark because I don't know the specifics of your equipment, so second-guess me and ask any questions you may have.

Don

in that 10ns you'll get 4 cycles of your 400mhz carrier

could you just use a 400Mhz source, divide it by 8 to get a 100mhz source (with 10ns wide pulses) and divide that by 500 (or 512) to get your ~100Khz timebase +-----------+ | ____ | clk1 | | | | --------+-(divide by 8)--+--(divide by 500)-+-|D _| +-|~~\\ out 400Mhz | | | Q|------| & )--- | +----(inveerter)-----|clk | +-|__/ | |____| | 3-input and gate | D-type flip-flop | +-----------------------------------------------+ if you want to sontroll the burst rate you'll need a programable divide stage instead of a fixed divide by 500 - what you put there depends on what form your control takes.

Bye. Jasen