[Q] pulse generaton with a carrier

[googler]

I am trying to find a way to generate a <10ns electrical pulse with
400MHz carrier inside the pulse at 0.1~1MHz repetition rate.

I was trying to combine a <10ns electrical pulse and a 400MHz carrier
with a frequency mixer. But between <10ns electrical pulse there is the
leakage of 400MHz with a small amplitude. So far pulse train looks fine
but I'd like to have a better pulse shape.

 

[Don Bowey]

On 9/12/05 8:42 PM, in article
1126582945.069897.257360@g14g2000cwa.googlegroups.com, "googler"
<gcsel@yahoo.com> wrote:

I am trying to find a way to generate a <10ns electrical pulse with
400MHz carrier inside the pulse at 0.1~1MHz repetition rate.

I was trying to combine a <10ns electrical pulse and a 400MHz carrier
with a frequency mixer. But between <10ns electrical pulse there is the
leakage of 400MHz with a small amplitude. So far pulse train looks fine
but I'd like to have a better pulse shape.

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

 

[googler]

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 ?



Don Bowey wrote:

On 9/12/05 8:42 PM, in article
1126582945.069897.257360@g14g2000cwa.googlegroups.com, "googler"
gcsel@yahoo.com> wrote:

I am trying to find a way to generate a <10ns electrical pulse with
400MHz carrier inside the pulse at 0.1~1MHz repetition rate.

I was trying to combine a <10ns electrical pulse and a 400MHz carrier
with a frequency mixer. But between <10ns electrical pulse there is the
leakage of 400MHz with a small amplitude. So far pulse train looks fine
but I'd like to have a better pulse shape.


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

 

[Don Bowey]

On 9/13/05 6:38 AM, in article
1126618729.493233.234290@o13g2000cwo.googlegroups.com, "googler"
<gcsel@yahoo.com> wrote:

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 ?



Don Bowey wrote:
On 9/12/05 8:42 PM, in article
1126582945.069897.257360@g14g2000cwa.googlegroups.com, "googler"
gcsel@yahoo.com> wrote:

I am trying to find a way to generate a <10ns electrical pulse with
400MHz carrier inside the pulse at 0.1~1MHz repetition rate.

I was trying to combine a <10ns electrical pulse and a 400MHz carrier
with a frequency mixer. But between <10ns electrical pulse there is the
leakage of 400MHz with a small amplitude. So far pulse train looks fine
but I'd like to have a better pulse shape.


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

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

 

[Jasen Betts]

On 2005-09-13, googler <gcsel@yahoo.com> wrote:

I am trying to find a way to generate a <10ns electrical pulse with
400MHz carrier inside the pulse at 0.1~1MHz repetition rate.

I was trying to combine a <10ns electrical pulse and a 400MHz carrier
with a frequency mixer. But between <10ns electrical pulse there is the
leakage of 400MHz with a small amplitude. So far pulse train looks fine
but I'd like to have a better pulse shape.

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