AnsweredAssumed Answered

analogLib source vs adsLib source

Question asked by PEOL on Feb 13, 2007
Latest reply on Feb 14, 2007 by nacim1
Hi,

I am simulating a differential amplifier and I wanted to compare the results from Cadence with the results from RFDE. I used a 2-tone signal (10M, 15M) and used a transient simulation (stop:400n, max step: 100p). I got slightly different results in RFDE depending on if I used the original Cadence isin source or the I_nTone source from adsLib (the wave form differed). There seems to be a phase shift between the sources even if I set the starting phases the same.
I did a quick test as shown below:

The two sources were put on a schematic with 1k resistor as load to gnd, only one frequency were considered:
1.) isin source connected to a 1k resistor.
Offset current: 10mA
Amplitude: 5mA
Frequency: 10M
DC current: 10mA
Initial phase for sinusoid: 0

2.) I_nTone source connected to a 1k resistor.
Freq1: 10M
I1: polar(5m,0)A
Idc: 10mA

To me, these two cases should be equivalent, but plotting the voltage over the two resistors reveals a 90deg phase shift between the two. Why is that? If I either specify I1 as polar(5m,-90) or change the initial sinusoid to +90 the traces ends up on top of each other.
I assume that you can use either type of source in RFDE (and not only sources from adsLib)?

Regards,
Peter  

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