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Wow. Thank you guys so much for your answers!!
This is the best forum ever :)
Reducing temp and/or making Vsb=0 in M2 didn't help.
But removing channel length modulation did :)
The models on cmosedu.com are level 3 and I didn't know how to remove CLM
in a level 3 model, so I made them level 1...
Hi,
I am simulating in LTSpice the self-biased reference shown below without any startup circuit.
This is fig. 20.15 of J. Baker 4th ed.
I used L=2u for all transistors with W/L as shown on the figure.
Models are N_1u and P_1u from cmosedu.com
I was wondering wether a start-up circuit is...
Thanks a lot for your answer, even if I didn't really get it :)
I'm doing a very simple noise analysis on the circuit attached (rc_noise.png).
I set output noise as voltage between out and gnd and runned the simulation.
Going thru Direct Plot -> Main form, I can choose either V^2/Hz or V/√Hz
in...
Hi everybody,
I'm learning how to perform noise simulation in Cadence/Spectre.
I've designed an simple RC network (R=1k, C=1p) and then performed a noise simulation between
1 and 100GHz and set as the output the voltage around C.
I would expect the famous shaped DSP with 4kTR (16.5e-18 V^2/Hz...
Cause if I don't, the results are nonsense. like this:
the pk2pk amplitude here is 170uV...
Actually, it still doesn't work properly even with plotwinsize=0.
The same problem seems to occur even when simulating
the tank with a current source only.
Don't understand why it's happening, but...
Well, actually, it seems to me that the inductor keeps drain's DC level at 5v.
This is why, as I mention in my first post, I expect a slightly higher gain in the tuned amp.
compared to the gain of the CS.
- - - Updated - - -
Yes, I'm gonna reduce the Q. I wasn't really focusing on it until...
Thank you very much!!
Next time I'll attach a zip.. thx.
I don't understand the mechanics behind the transient simulation enough to understand how its timestep
can modify the resonance frequency. I need to study a bit :)
Don't you think that this is the effective frequency of the signal that...
44/16 is not 4, and as I said above, the amplitude of ic is actually 0.44/2 which is 0.22V.
0.44 V is a peak-to-peak value while 0.16 V is not
So you get 0.22 instead of 0.16 which is not that surprising
pif
The input voltage has a 1V offset which, as DC simulation told me, is an acceptable bias
what about it?
That's a good question whose answer is not that obvious :)
I just want to see if simulation gives me the result I expect.
In particular, that at the resonnant frequency, the gain of the...
Hi.
It seems to me that 0.44mA is a peak-to-peak value, while 0.16mA is a peak theoretical value..
So you should compare 0.16 with 0.44/2=0.22
Not exactly equals but sounds good to me.
Hi everybody.
I'm trying to simulate a tuned amplifier in LTSpice in order to get a better grasp on its operation.
This is a first step in my studying of oscillators.
Anyway, I am getting weird results that I am not able to explain.
I would be very grateful if some of you guys could help
I'd...
That worked!!
As explained in the thread you linked, I just had to check the "save subcircuit voltages/currents" boxes in the control panel.
Very sorry, I tried to run a search on "LTSpice" in the forum before posting, but apparently, i did that wrong...
Thank you so much
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