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How to synchronize multiple function/arb waveform generators

Question asked by lhornburg

on Feb 10, 2010
Latest reply on Aug 3, 2020 by JodyMusto

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There are two methods of using the external clock reference to synchronize the outputs of multiple function/arbitrary waveform generators. Each function/arbitrary waveform generator requires an external clock reference. The external clock reference is standard on the 33250A, and is option 001 on the 33210A and 33220A. Option 001 is available as a retrofitp

The first method has the function/arbitrary waveform generator output a continuous waveform. You can get a more precise phase relationship using this method and is easier to use when making changes to the phase relationship between the generators.

The second method uses infinite burst mode. It is a bit more complex to set up, but once it is set up it is easier to use when making changes to the waveform shape or frequency. While it is not as accurate as the first method, the additional trigger error is not a significant factor for many applications.

CONTINUOUS MODE

On the primary unit, connect a BNC cable to the 10 MHZ OUT. On the secondary unit, connect the clock reference cable to the 10 MHZ IN.

Power on both units and configure waveform (shape, frequency, amplitude, offset, etc). Enable the output on both units by pressing OUTPUT.

Align the outputs of both units:

Connect outputs to an oscilloscope or counter and find the current phase relationship.
On the SECONDARY UNIT:
- Press the UTILITY key on the front panel and select OUTPUT SETUP on the softkeys.
- Select the softkey for ADJUST PHASE.
- Using the **** (recommended), adjust the phase until both outputs are aligned at 0 phase.
- Press the SET 0 PHASE softkey.
- Adjust the PHASE using the **** or keypad to the desired phase relationship (eg 180.000 degrees).
Remove output connections from oscilloscope/counter and reapply to application.
To make a change to waveshape or frequency, make the change and repeat the alignment procedure on both units. To make a change to the phase relationship, simply re-adjust the phase as desired (eg 90.000 degrees, 180.010 degrees).

INFINITE BURST MODE

On the primary unit, connect BNC cables to the 10 MHZ OUT and the EXT TRIG. On the secondary unit, connect the clock reference cable to the 10 MHZ IN and the trigger cable to the EXT TRIG.

Power on both units and configure waveform (shape, frequency, amplitude, offset, etc).

Configure BURST on both units. Press the BURST key from the front panel. Starting from the left, use the softkeys to toggle between parameters to the following settings:

Select N CYCLE
Select INFINITE
START PHASE may be set. Set it to the phase you wish the waveform to have on each unit. For example, if two units should have a phase relationship of 180 degrees, set the primary to 0 degrees, and the secondary to 180 degrees. You can also set -90 degrees and +90 degrees if you wish.
BLANK KEY
BLANK KEY
TRIGGER SETUP: This will open a new menu. From left to right, again use the softkeys to toggle between parameters:
ON THE PRIMARY UNIT:
- SOURCE: Set to MANUAL (front panel trigger key will light).
- BLANK KEY
- TRIG OUT: Select a slope, either positive or negative.
- BLANK KEY
- BLANK KEY
- DONE: Press this key to finish
ON THE SECONDARY UNIT:
- SOURCE: Set to EXT
- SLOPE: Set to match slope of the primary TRIG OUT setting
- BLANK KEY
- BLANK KEY
- BLANK KEY
- DONE: Press this key to finish
Turn on the OUTPUT if not already done. Press the TRIGGER key on the primary unit to start the output on both units.

To make a change (frequency, waveshape, phase, etc) press the TRIGGER key on both units to stop the infinite burst. Make the changes, then press the TRIGGER key on the primary unit to start the output on both units.

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bwaj Apr 12, 2013 5:26 PM

I am trying to synchronize 33120A with 33250A. I followed the literature found on web published by Agilent - "How to Connect Two or More Signal Generators to Create a Multi-Channel Waveform Generator; Application Note 1426" - [http://cp.literature.agilent.com/litweb/pdf/5988-8151EN.pdf] .

I connected a BNC cable from 10MHz ref out of 33120A to 10MHz ref in of 33250A. I kept the same frequency (200kHz) and signal shape (square wave) on both and with the help of Oscilloscope, I reduced the phase between the 2 signals to zero. Then I changed the output signal to arb signal on 33250A which has 64000 data points with repetition rate of 3.125kHz and peak to peak amplitude of 100mV.

Now, I have a couple of questions:

1. After changing to arb wave in 33250A, I couldn't lock the 2 signals on oscilloscope. I triggered the arb signal on the scope, but the square wave signal from 33120A was walking around still. Why is that? How can I avoid the walking of square wave signal if possible?

2. In order to further understand, I reverted back to square wave on 33250A and frequency back to 200kHz, I was surprised to see the phase between the 2 signals on Oscilloscope is not zero anymore. (I didn't remove the BNC cable or turn off any of the systems in the middle of this trial). Why does this happen?

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cldiller

@ bwaj on Apr 15, 2013 2:44 PM

I hope the application note was helpful in getting you started with synchronizing multiple generators. I also like to use the measurement brief at http://cp.literature.agilent.com/litweb/pdf/5990-3467EN.pdf. Let's see if we can answer some of your questions.

> {quote:title=bwaj wrote:}{quote}
> 1. After changing to arb wave in 33250A, I couldn't lock the 2 signals on oscilloscope. I triggered the arb signal on the scope, but the square wave signal from 33120A was walking around still. Why is that? How can I avoid the walking of square wave signal if possible?

With these specific frequencies, you would expect to get 64 cycles of the square wave from the 33120A for every arb cycle. There might be a couple of different issues at play.

First, the 33120A generates its square wave by running a sine wave signal through an analog comparator. You could be seeing some jitter due to small variations in the signal or the comparator.

Second, the 33120A does not have the frequency accuracy of the 33250A. The 33120A specified frequeny accuracy is 20 ppm in one year.compared to 2 ppm for the 33250A. To meet this higher frequency accuracy, the 33250A uses a larger phase increment register and therefore has a smaller quantization error. This error could produce a slow phase creep between the two signals.

> {quote:title=bwaj wrote:}{quote}
> 2. In order to further understand, I reverted back to square wave on 33250A and frequency back to 200kHz, I was surprised to see the phase between the 2 signals on Oscilloscope is not zero anymore. (I didn't remove the BNC cable or turn off any of the systems in the middle of this trial). Why does this happen?

The function generator only synchronizes to the 10 MHz clock signal -- it does not keep track of what the opposite unit considers to be 0 degrees. Every time you change the shape or the timing of the signal, the function generator performs the update then outputs the new waveform. It will still be synchronized to the external 10 MHz clock signal, but the new phase relationship will be random.

Best Regards,
Cheryl

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arashm @ bwaj on Aug 21, 2013 3:02 PM

Hi,

I am trying to synchronize two 33120A signal generators. I need two signals with frequency of 500 kHz, 180 phase difference and Amplitude of 2 Vp-p.
On the rear panel, I have only "Ext Trig/FSK/Burst" and "AM Modulation" terminal. I mean the option of "Ref in" or out is not available. Do you know how I can synch them? I also tried to use the manual but I was not able to do it.
I'd be thankful if you can help me.

Arash

Edited by: ArashM on Aug 21, 2013 4:01 PM

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xiaoleic Aug 3, 2020 7:38 AM

Hi,

Regarding the first method you introduced. I want to output 26 MHz from primary unit, and 19.2 Mhz from secondary.

I have primary 10 Mhz OUT connected to secondary 10 MHz IN. I then put outputs of both units on scope. I can see that the two signals are NOT static relative to each other. While one waveform is static, the other is walking.

However, if I set both outputs to 26 Mhz, I can see on scope the waveforms are static relative to each other. So I can know that they are synchronous.

So , my question is : in the former case (where two output freq. are different), how can I know that the two outputs are synchronous?

Both primary and secondary units I use are 33250A.

Thanks.

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IAMSHYBOY May 6, 2014 3:47 AM

Hi Team,
if I have _*33522B*,_ Can I synchonizine for generate 4 sine waves that are all phase locked to each other.Plese advice?

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gemsupport

@ IAMSHYBOY on Jun 23, 2015 2:01 PM

Hi. There is a video on YouTube showing how to synchronize multiple waveform generators. It demonstrates the method to sync four waveforms, but you can expand to more generators and outputs as well.

Check it out at https://www.youtube.com/watch?v=OW2ohMS7SZ8

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Laurens001 Jun 3, 2014 10:22 AM

I have a 33522A.

I would like to generate a single 25ns pulse at 10Hz on channel 1
and generate 128x 25ns pulses at 1280Hz on channel 2
I would like the start of pulse to be the same for Ch1 and Ch2

I have an extra 33521A that can act as a trigger.

I'm unable to get the burst modes to phase align the outputs on channels 1 and 2 - the moment that I turn on burst mode, then the phase sync possibility disappears. Running latest FW.

Is this possible?

Actions

JodyMusto Aug 14, 2020 1:12 PM

Hello...the terminology can be confusing because, besides arbitrary waveforms, ARBs can generate predefined functions, such as sine, square, triangular, and sawtooth waveforms. But generating these and other predefined signals is the mainstay of SFGs.

rigid flex pcb design for assembly guidelines

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8 Replies

bwaj Apr 12, 2013 5:26 PM
Mark Correct
Correct Answer
I am trying to synchronize 33120A with 33250A. I followed the literature found on web published by Agilent - "How to Connect Two or More Signal Generators to Create a Multi-Channel Waveform Generator; Application Note 1426" - [http://cp.literature.agilent.com/litweb/pdf/5988-8151EN.pdf] .

I connected a BNC cable from 10MHz ref out of 33120A to 10MHz ref in of 33250A. I kept the same frequency (200kHz) and signal shape (square wave) on both and with the help of Oscilloscope, I reduced the phase between the 2 signals to zero. Then I changed the output signal to arb signal on 33250A which has 64000 data points with repetition rate of 3.125kHz and peak to peak amplitude of 100mV.

Now, I have a couple of questions:

1. After changing to arb wave in 33250A, I couldn't lock the 2 signals on oscilloscope. I triggered the arb signal on the scope, but the square wave signal from 33120A was walking around still. Why is that? How can I avoid the walking of square wave signal if possible?

2. In order to further understand, I reverted back to square wave on 33250A and frequency back to 200kHz, I was surprised to see the phase between the 2 signals on Oscilloscope is not zero anymore. (I didn't remove the BNC cable or turn off any of the systems in the middle of this trial). Why does this happen?
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- cldiller @ bwaj on Apr 15, 2013 2:44 PM
  Mark Correct
  Correct Answer
  I hope the application note was helpful in getting you started with synchronizing multiple generators. I also like to use the measurement brief at http://cp.literature.agilent.com/litweb/pdf/5990-3467EN.pdf. Let's see if we can answer some of your questions.
  
  > {quote:title=bwaj wrote:}{quote}
  > 1. After changing to arb wave in 33250A, I couldn't lock the 2 signals on oscilloscope. I triggered the arb signal on the scope, but the square wave signal from 33120A was walking around still. Why is that? How can I avoid the walking of square wave signal if possible?
  
  With these specific frequencies, you would expect to get 64 cycles of the square wave from the 33120A for every arb cycle. There might be a couple of different issues at play.
  
  First, the 33120A generates its square wave by running a sine wave signal through an analog comparator. You could be seeing some jitter due to small variations in the signal or the comparator.
  
  Second, the 33120A does not have the frequency accuracy of the 33250A. The 33120A specified frequeny accuracy is 20 ppm in one year.compared to 2 ppm for the 33250A. To meet this higher frequency accuracy, the 33250A uses a larger phase increment register and therefore has a smaller quantization error. This error could produce a slow phase creep between the two signals.
  
  > {quote:title=bwaj wrote:}{quote}
  > 2. In order to further understand, I reverted back to square wave on 33250A and frequency back to 200kHz, I was surprised to see the phase between the 2 signals on Oscilloscope is not zero anymore. (I didn't remove the BNC cable or turn off any of the systems in the middle of this trial). Why does this happen?
  
  The function generator only synchronizes to the 10 MHz clock signal -- it does not keep track of what the opposite unit considers to be 0 degrees. Every time you change the shape or the timing of the signal, the function generator performs the update then outputs the new waveform. It will still be synchronized to the external 10 MHz clock signal, but the new phase relationship will be random.
  
  Best Regards,
  Cheryl
  Like • Show 1 Like1
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- arashm @ bwaj on Aug 21, 2013 3:02 PM
  Mark Correct
  Correct Answer
  Hi,
  
  I am trying to synchronize two 33120A signal generators. I need two signals with frequency of 500 kHz, 180 phase difference and Amplitude of 2 Vp-p.
  On the rear panel, I have only "Ext Trig/FSK/Burst" and "AM Modulation" terminal. I mean the option of "Ref in" or out is not available. Do you know how I can synch them? I also tried to use the manual but I was not able to do it.
  I'd be thankful if you can help me.
  
  Arash
  
  Edited by: ArashM on Aug 21, 2013 4:01 PM
  Like • Show 0 Likes0
  Actions
xiaoleic Aug 3, 2020 7:38 AM
Mark Correct
Correct Answer
Hi,

Regarding the first method you introduced. I want to output 26 MHz from primary unit, and 19.2 Mhz from secondary.

I have primary 10 Mhz OUT connected to secondary 10 MHz IN. I then put outputs of both units on scope. I can see that the two signals are NOT static relative to each other. While one waveform is static, the other is walking.

However, if I set both outputs to 26 Mhz, I can see on scope the waveforms are static relative to each other. So I can know that they are synchronous.

So , my question is : in the former case (where two output freq. are different), how can I know that the two outputs are synchronous?

Both primary and secondary units I use are 33250A.

Thanks.
Like • Show 0 Likes0
Actions
IAMSHYBOY May 6, 2014 3:47 AM
Mark Correct
Correct Answer
Hi Team,
if I have _*33522B*,_ Can I synchonizine for generate 4 sine waves that are all phase locked to each other.Plese advice?
Like • Show 0 Likes0
Actions
- gemsupport @ IAMSHYBOY on Jun 23, 2015 2:01 PM
  Mark Correct
  Correct Answer
  Hi. There is a video on YouTube showing how to synchronize multiple waveform generators. It demonstrates the method to sync four waveforms, but you can expand to more generators and outputs as well.
  
  Check it out at https://www.youtube.com/watch?v=OW2ohMS7SZ8
  Like • Show 0 Likes0
  Actions
Laurens001 Jun 3, 2014 10:22 AM
Mark Correct
Correct Answer
I have a 33522A.

I would like to generate a single 25ns pulse at 10Hz on channel 1
and generate 128x 25ns pulses at 1280Hz on channel 2
I would like the start of pulse to be the same for Ch1 and Ch2

I have an extra 33521A that can act as a trigger.

I'm unable to get the burst modes to phase align the outputs on channels 1 and 2 - the moment that I turn on burst mode, then the phase sync possibility disappears. Running latest FW.

Is this possible?
Like • Show 0 Likes0
Actions
JodyMusto Aug 14, 2020 1:12 PM
Mark Correct
Correct Answer
Hello...the terminology can be confusing because, besides arbitrary waveforms, ARBs can generate predefined functions, such as sine, square, triangular, and sawtooth waveforms. But generating these and other predefined signals is the mainstay of SFGs.

rigid flex pcb design for assembly guidelines
Like • Show 0 Likes0
Actions

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