Hello All,
This might not be the best forum, but I started in the network analyzer application forum with no replies so I am reposting here.
+_Task_+
I have been task with measuring the switching time of a digital attenuator to within 0.1 dB and 1 degree of the final value and the expected time is 30 ns. The frequencies are 1 to 3 GHz. The attenuator is a 2 bit 6 dB step (18 dB total). At 1 GHz the phase delta is less than 1 degree and at 3 GHz it is about 5 degrees / step.
PNA-X
I looked into this, but even with the IF BW wide open in CW mode, I can not get the time resolution. This would be perfect because I could do a response calibration and get both amplitude and phase simultaneously.
+Amplitude+
-Power Sensor_ (U2021XA) are not good since they do not the time resolution.
_Crystal Detector_ saw about 55 mV for 18 dB or I would need a step of 0.03 mV step for the oscilloscope. Unfortunately the oscilloscope I have access to is over 10 years old (non Agilent) and yields 10 times that for a error term.
_Spectrum Analyzer_ (Non Agilent) had 50 MHz resolution BW but the timing was way off.
_Oscilloscope_ I had to settle on using the oscilloscope directly since it was digital and had a 50 ohm input. Data was sampled at 10 GS/s. In the reference state (0 dB) I maximized the voltage on the screen. It did not have a envelope function, so I just use the maximum function. I also am doing a 400 point running averaging on the maximum data to "smooth" it. It seems reasonable and the customer is happy, but I am not since I typically see 0.1 dB ripple on the smoothed data. It is even worse when I am in the 18 dB state.
+Phase+
Very limited here. I put together a discriminator. I split the source. One path has the line stretcher and goes into the LO port of a double balance mixer. The other port goes into a variable attenuator, the device under test and into the RF port of the mixer. The IF port has a low pass filter with at least 80 dB of reject at the frequency of interest. Here I have been finding all sorts of little issues that are much to long to go into. I am looking into a getting a phase detector from Holzworth Instrument to see if this helps with some of my issues.
Been thinking about VSA and the new Infiniium S-Series (10 bit A/D). (Ideas?)
Also, thinking of using a oscilloscope directly and taking the mixer out. Take the two signals and go directly into the oscilloscope. Adjust the line stretcher for identical zero crossing. Since the frequency is known I could calculated the phase offset (time). Amplitude can be done also.
So I am looking for any inputs to get the high accuracy in value and timing.
Thanks for any advice in advance.
Michael Virostko
Integrated Device Technology
This might not be the best forum, but I started in the network analyzer application forum with no replies so I am reposting here.
+_Task_+
I have been task with measuring the switching time of a digital attenuator to within 0.1 dB and 1 degree of the final value and the expected time is 30 ns. The frequencies are 1 to 3 GHz. The attenuator is a 2 bit 6 dB step (18 dB total). At 1 GHz the phase delta is less than 1 degree and at 3 GHz it is about 5 degrees / step.
PNA-X
I looked into this, but even with the IF BW wide open in CW mode, I can not get the time resolution. This would be perfect because I could do a response calibration and get both amplitude and phase simultaneously.
+Amplitude+
-Power Sensor_ (U2021XA) are not good since they do not the time resolution.
_Crystal Detector_ saw about 55 mV for 18 dB or I would need a step of 0.03 mV step for the oscilloscope. Unfortunately the oscilloscope I have access to is over 10 years old (non Agilent) and yields 10 times that for a error term.
_Spectrum Analyzer_ (Non Agilent) had 50 MHz resolution BW but the timing was way off.
_Oscilloscope_ I had to settle on using the oscilloscope directly since it was digital and had a 50 ohm input. Data was sampled at 10 GS/s. In the reference state (0 dB) I maximized the voltage on the screen. It did not have a envelope function, so I just use the maximum function. I also am doing a 400 point running averaging on the maximum data to "smooth" it. It seems reasonable and the customer is happy, but I am not since I typically see 0.1 dB ripple on the smoothed data. It is even worse when I am in the 18 dB state.
+Phase+
Very limited here. I put together a discriminator. I split the source. One path has the line stretcher and goes into the LO port of a double balance mixer. The other port goes into a variable attenuator, the device under test and into the RF port of the mixer. The IF port has a low pass filter with at least 80 dB of reject at the frequency of interest. Here I have been finding all sorts of little issues that are much to long to go into. I am looking into a getting a phase detector from Holzworth Instrument to see if this helps with some of my issues.
Been thinking about VSA and the new Infiniium S-Series (10 bit A/D). (Ideas?)
Also, thinking of using a oscilloscope directly and taking the mixer out. Take the two signals and go directly into the oscilloscope. Adjust the line stretcher for identical zero crossing. Since the frequency is known I could calculated the phase offset (time). Amplitude can be done also.
So I am looking for any inputs to get the high accuracy in value and timing.
Thanks for any advice in advance.
Michael Virostko
Integrated Device Technology
I just PM'ed you to give me a call.
Al