hello
I need test the time response of a logarithmic amplifier( DC to 1.4GHZ, -60 to 0 dBm dynamic range)
So , I need a Rf pulse modulated with rise time better than 30nseg and level between -60 and 0 dBm.
I have a analog signal generator Agilent E4428C ESG, wich internal pulse modulation rise/fall time 150nseg. And Agilent 33220A 20 MHz function / Arbitrary Waveform Generator with a pulse rise time better 15 ns .
My questions: with these two intruments Can I performe the modulated pulse that I need?
thanks
I need test the time response of a logarithmic amplifier( DC to 1.4GHZ, -60 to 0 dBm dynamic range)
So , I need a Rf pulse modulated with rise time better than 30nseg and level between -60 and 0 dBm.
I have a analog signal generator Agilent E4428C ESG, wich internal pulse modulation rise/fall time 150nseg. And Agilent 33220A 20 MHz function / Arbitrary Waveform Generator with a pulse rise time better 15 ns .
My questions: with these two intruments Can I performe the modulated pulse that I need?
thanks
The pulse modulator is not a linear modulator but rather it works on a threshold of roughly 0.5 V (some hysteresis ~0.05 V slop). You could put a pulse with a rise time as slow as 1 second and the E4428C would latch at the threshold and the rise time of the RF pulse would still be ~100 ns or as fast as it can go.
Although the specified rise/fall time is 150 ns, you might find the typical (not warranted) rise/fall times are faster. I've attached a trace from an oscilloscope showing a 4-us pulse at 500 MHz RF using the internal generator of an E4438C (vector version of your E4428C). The rise time is about 40 or 50 ns; just understand that this is only a sample, not warranted performance. Using a 33522A function generator pulse with rise time of 30 ns produces the EXACT same rise/fall times.
Now, if you have a vector E4438C available, it has standard AM capability as well as "wideband AM." With this wideband AM input, you can use an external pulse to linearly modulate the RF and I've seen rise times as fast as 10 ns (which is as fast as my 33522A will go). I've also attached a plot of this showing this.
So the short answer is "no" you can't make the E4428C rise time any faster by using an external pulse from a function generator but the typical performance is better than the specification in the manual. The alternative is to use an E4438C with wideband AM and external pulse source or consider an N5281A analog MXG which has pulse rise times as fast as 7 ns without external pulse signals.