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How to Use ADS to simulate op amplifier?

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Mar 3, 2002
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ads op amplifier

I have used a op amplifier-LMH6703MF(National Semiconductor) for RF application, National Semiconductor provides a spice model file for LMH6703MF named LMH6703T.MOD, I import the LMH6703T.MOD into ADS and use a S-param simulator to simulate the circuit but the result is wrong.Who experts here can help to simulate the circuit with correct result?Thanks very much!

for more information about LMH6703MF please refer to:**broken link removed**


It will be very helpful if you post the silumation file here. people could not guess that what wrong when you say "the results is wrong" Cound you post the ADS project file? I can get the op-amp model file but I dont know what do u need. I have looked at the datasheet. If you need the transient responses, you can use transient in ADS. For the S-parameter. I guess that you will not get a good result since the input impedance of the op-amp is very high.


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But Can the SPICE model be used to make a S-Parameter simulation to get frenquency response just like which test the circuit use a Network Analyzer?

How to Use @DS to simulate op amplifier?

I have tried it but it does not give me any gain. I use HB simulation. I also connect the NSD (shut down control) to Vcc/Gnd. It gave the same result.

How to Use @DS to simulate op amplifier?

Isn't my guess a model to have mistake?

How to Use @DS to simulate op amplifier?

maybe the model can not be used to s-param simulate?

How to Use @DS to simulate op amplifier?

I have used both HB/and transient simulator. It is the same, no gain.

But,according to the application technote OA-11 given by national semiconductor,Voltage gain will be (1+Rf/Rg)=3 and the power gain will be
3.5dB,but why we get no gain from ads?

Re: How to Use @ds to simulate op amplifier?

Can i ask you a question, what is the program you used to draw this figure? (this is question's beyond your request, but forgive me)

Re: How to Use @DS to simulate op amplifier?

Needbias said:
I use ads2005a.

You didn't get my question, I don't mean what is the program you will use to simulate or work with your circuit, but i mean the above figure itself, it's not drawon on ads, but on another program, what's that program that draws that beutiful figures, I am asking about it to use it to draw figures in my papers and so on...


How to Use @DS to simulate op amplifier?

Sorry,The fig is draw by national semiconductor,you can find it on application technote OA-11 of national semiconductor. but I think you can draw it with microsoft visio.

I checked you ads file. It looks like you were confused by the pin number of the subcircuit. The correct order should be

Symbol pin# Name Subcircuit Name
pin1 in+ node3
pin2 in- node4
pin3 VDD node6
pin4 VSS node2
pin5 out node1
pin6 shut_dn_n node5

Usually we do not do S-parameter simulation for an opam since it is used in low frequency applications. Instead, AC simulation is enough to get all the results you need.

I modified your ads file, both S-parameter and AC simulations are running OK.

Added after 3 minutes:

sorry, miss the attachment


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How to Use @DS to simulate op amplifier?

Dear jon2000,
Good job! thank you very much!


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