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# How to generate a ramp voltage supply in ADS

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#### mohamis288

##### Full Member level 3
Hello,

I wish to generate a DC signal which it begins with a ramp function in ADS. I know two solution in ADS in order to do this.

1) using "Ramp" component in ADS. I have tried to do this, but it did not produce any ramp signal. I put the image in the following:

For TStep I have written maxTimeStep in transient simulation. Anyway, I think this component is not compatible with transient simulation. see the following link:

I also want to know how to simulate this type of components.

2) second way to produc a ramp signal is ramp() equation. we define a simple V_DC signal and for its value we give ramp() as shown below:

But it is a continuous ramp function and it is only defined using the parameter of transient simulation. I would appreciate any help.
Thank you

Solution
The second approach with the DC voltage source is the right way to go but it would be better to use the pwl() function in an expression to set the Vdc parameter.

pwl(time, T1, V1, T2, V2, ..., TN, VN)

This would allow you to set the time delay for the start for ramp and also the stop time at the appropriate maximum voltage.

This function is periodic in that after TN it repeats but you can set that value as high as needed for the transient simulation.
The second approach with the DC voltage source is the right way to go but it would be better to use the pwl() function in an expression to set the Vdc parameter.

pwl(time, T1, V1, T2, V2, ..., TN, VN)

This would allow you to set the time delay for the start for ramp and also the stop time at the appropriate maximum voltage.

This function is periodic in that after TN it repeats but you can set that value as high as needed for the transient simulation.

The second approach with the DC voltage source is the right way to go but it would be better to use the pwl() function in an expression to set the Vdc parameter.

pwl(time, T1, V1, T2, V2, ..., TN, VN)

This would allow you to set the time delay for the start for ramp and also the stop time at the appropriate maximum voltage.

This function is periodic in that after TN it repeats but you can set that value as high as needed for the transient simulation.
Thank you,
But I do not know why in my original circuit, I have time step problem with some components and functions. the link to my problem is shown here:

PAY ATTENTION!! I do not have problem with this function lonely, I mean when I simulate this source alone without any other connection, this will produce ramp successfully. The problem occurs once I connect it to the original circuit (IC's drain-source voltage lead) .

Are you questioning about using the Ramp source in your transient style circuit simulation? You have had exactly this same problem before but then it was the PulseRF source:

Again...

This Ramp source is from the Signal Processing (DSP) components in ADS, Timed library. It is intended for use within the ADS Ptolemy domain (the clue is the big arrow on the symbol) that can include Circuit Envelope Simulations and certain Transient/Convolution Simulations for modulated signal simulations. However, it will never work for regular circuit level simulations like S-parameter, AC, Harmonic Balance and regular Transient Time Domain (Spice like) simulations.

You are obviously finding these sorts of components and trying to use them when they are not a valid selection for the level of simulation you are performing. It would be best if you remove this choice entirely from your design environment. Go to the ADS main window when you have this workspace open and select the command - Design Kits > Manage Libraries... In the following window 1. Find the entry for dsp.defs. 2. Remove that library so that it is no longer referenced when this workspace is opened. This will reduce the choice of libraries/palette entries so that only those libraries relevant for circuit simulation, analog_rf, are presented.

Similarly, when you create a new workspace make sure that the dsp,defs library entry in NOT selected.

mohamis288

### mohamis288

Points: 2
Are you questioning about using the Ramp source in your transient style circuit simulation? You have had exactly this same problem before but then it was the PulseRF source:

Again...

This Ramp source is from the Signal Processing (DSP) components in ADS, Timed library. It is intended for use within the ADS Ptolemy domain (the clue is the big arrow on the symbol) that can include Circuit Envelope Simulations and certain Transient/Convolution Simulations for modulated signal simulations. However, it will never work for regular circuit level simulations like S-parameter, AC, Harmonic Balance and regular Transient Time Domain (Spice like) simulations.

You are obviously finding these sorts of components and trying to use them when they are not a valid selection for the level of simulation you are performing. It would be best if you remove this choice entirely from your design environment. Go to the ADS main window when you have this workspace open and select the command - Design Kits > Manage Libraries... In the following window 1. Find the entry for dsp.defs. 2. Remove that library so that it is no longer referenced when this workspace is opened. This will reduce the choice of libraries/palette entries so that only those libraries relevant for circuit simulation, analog_rf, are presented.

View attachment 177932

Similarly, when you create a new workspace make sure that the dsp,defs library entry in NOT selected.
Hello,
NO. I do not use the " ramp" component and I am using V_DC with "pwl" as its value. I faced an error when I connect this source to the IC.

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