Does your CMOS Ring Oscillator use the same MOSFET models (BSIM3V322(P)) as the "Push Push" Oscillator example?
The circuit appears to go into stagnant mode. The output meanders in a middle voltage range, rather than a definite on-or-off condition.
Can you set the very first input to low or high initially? Or connect it briefly to a supply lead as you start up?
We understood that the problem is with the unavailability of the PDK for 0.18um process. The Generic GenBicmos35 PDK uses a channel length of 0.35um. Are there any PDKs of 0.18um available for free download?
You can get PDKs only from the foundries or their representatives against signing an NDA (s. here), or GPDKs from the EDA tool companies.
But I guess you just need appropriate model files for a 0.18µm process. Why not use the free PTM models? Click Latest Models, then scroll down to the bottom, where you still can find 180nm BSIM3 level=49 NMOS & PMOS SPICE models.
I don't see any model, but only the parameters. Is there any way to export all the parameters at once into the model, instead of manually one by one?
Code PHP (brief) - [expand] 1 2 3 4 5 6 7 * * Predictive Technology Model Beta Version * 180nm NMOS SPICE Parametersv (normal one) * .model NMOS NMOS +Level = 49
x1 drain gate source substrate NMOS W=1e-6 L=180n * x1 is the individual FET's name; NMOS refers to the model.
Now the problem is how to adjust its width. How to make the model's length and width as variables?
.DC sweep wn LIN 10 0.1u 1u
Usually in (H)SPICE simulators you can assign a parameter (e.g. wn, ln for NMOS), give it a preliminary value, and in the analysis sweep it between limit values:
Some simulators can sweep multiple parameters, HSPICE e.g. with the DATA structure.
This tutorial shows how it's done with the Cādence tool (s. pp. 15 ff): View attachment 120285
Well done, congrats! The .SUBCKT + M1 method is only necessary for the sweep, not for building a netlist. For a netlist without sweeping parameters, you could assign the width and length for individual transistors directly:Instead we added .SUBCKT command to the NETLIST file. Now the width and length is accessible and they can be varied.
MS1 1 2 3 4 CMOSN W=1u L=0.18u
MS2 1 2 5 5 CMOSP W=3u L=0.18u
. . .
The original model file doesn't contain parameters for W & L , but it's necessary to assign these values for each individual transistor, s. above (or with your .SUBCKT method for sweeping).1. Which parameter in this model file corresponds to the length and width of the MOSFET? In case it is not there, how to calculate it? We need the minimum and maximum length and width for simulation purposes.
T92Y was a (6 years old) TSMC 0.18µm wafer lot, these data had been published freely by MOSIS in former days (still in 2015, AFAIR).2. How to verify this model is for 180nm technology?
You don't change parameters of a model file - apart from W & L - because this foundry-provided model description describes how their MOSFET will behave, and this is what you want to see by simulation - and later in reality, perhaps.3. Can the parameters in the model be changed for a low voltage/power consumption?
You don't change parameters of a model file - apart from W & L - because this foundry-provided model description describes how their MOSFET will behave, and this is what you want to see by simulation - and later in reality, perhaps.
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