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19th August 2017, 14:12 #41
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Re: Gyrator implementation of chip inductor
I dont have any idea.
That is true. You have to write approximate equations in order to understand the circuit behavior not getting stuck in detailed small signal calculations.
in that formula if ro is high, gm4=gm3 and rd=1/gm3 (since ro3 is high), again you will reach Gm=gm1 as i wrote earlier.

22nd August 2017, 04:46 #42
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Re: Gyrator implementation of chip inductor
Regarding transconductance values determination, should I use manual calculation or simulation ? As for transconductance simulation, how would I do it ? in AC smallsignal simulation ? I could not find any spice examples on transconductance measurement.

22nd August 2017, 07:43 #43
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Re: Gyrator implementation of chip inductor
for BSIM3v3 NMOS model as in http://sprunge.us/EGHI or below , how do I find out which parameter is the transconductance, gm ?
There is no documentation regarding this at http://ngspice.sourceforge.net/exter...330_manual.pdf
*model = bsim3v3
*Berkeley Spice Compatibility
* Lmin= .35 Lmax= 20 Wmin= .6 Wmax= 20
.model N1 NMOS
+Level= 8
+version=3.3.0
+Tnom=27.0
+Acnqsmod=1 elm=3
+Capmod=3
+Nch= 2.498E+17 Tox=9E09 Xj=1.00000E07
+Lint=9.36e8 Wint=1.47e7
+Lintnoi=1e9
+Vth0= .6322 K1= .756 K2= 3.83e2 K3= 2.612
+Dvt0= 2.812 Dvt1= 0.462 Dvt2=9.17e2
+Nlx= 3.52291E08 W0= 1.163e6
+K3b= 2.233
+Vsat= 86301.58 Ua= 6.47e9 Ub= 4.23e18 Uc=4.706281E11
+Rdsw= 650 U0= 388.3203 wr=1
+A0= .3496967 Ags=.1 B0=0.546 B1= 1
+Dwg = 6.0E09 Dwb = 3.56E09 Prwb = .213
+Keta=3.605872E02 A1= 2.778747E02 A2= .9
+Voff=6.735529E02 NFactor= 1.139926 Cit= 1.622527E04
+Cdsc=2.147181E05
+Cdscb= 0 Dvt0w = 0 Dvt1w = 0 Dvt2w = 0
+Cdscd = 0 Prwg = 0
+Eta0= 1.0281729E02 Etab=5.042203E03
+Dsub= .31871233
+Pclm= 1.114846 Pdiblc1= 2.45357E03 Pdiblc2= 6.406289E03
+Drout= .31871233 Pscbe1= 5000000 Pscbe2= 5E09 Pdiblcb = .234
+Pvag= 0 delta=0.01
+ Wl = 0 Ww = 1.420242E09 Wwl = 0
+ Wln = 0 Wwn = .2613948 Ll = 1.300902E10
+ Lw = 0 Lwl = 0 Lln = .316394
+ Lwn = 0
+kt1=.3 kt2=.051
+At= 22400
+Ute=1.48
+Ua1= 3.31E10 Ub1= 2.61E19 Uc1= 3.42e10
+Kt1l=0 Kt1=0.1 Prt=764.3

22nd August 2017, 07:43

22nd August 2017, 08:23 #44
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Re: Gyrator implementation of chip inductor
how do I find out which parameter is the transconductance, gm ?

22nd August 2017, 09:05 #45
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23rd August 2017, 08:11 #46
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Re: Gyrator implementation of chip inductor
One guy told me that
"gm is the point behind the yaxis where the lines in saturation meets if you extrapolate them through the linear region when you sweep vds for stepping vgs"
Do you guys have any insights ?

23rd August 2017, 15:34 #47
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Re: Gyrator implementation of chip inductor
you are applying large signal !
When you apply large signal to your inverter, it wont behave like a gmcell. It will act like a digital gate.
If your inverter has VDD and GND you should apply Vin=VDD/2 + Vac.sin(wt) and Vac should be small signal.
when your inputs rises to 3 volts PMOS transistor turns off you should not let them (NMOS and PMOS turn off).
so your amplitude should be max vth (Nmos) < Vin < VDDvth(pmos) and also careful about output swing as well vdsat (nmos) < Vout < VDDVdsat(pmos) in order to be sure that both transistors and
operating at saturation
Example: VDD=3 and GND , vth=0.5, Vdsat=0.2
0.5 < Vin < 2.5 and 0.2 < vout < 2.8
Again I suggest you to read some reference books like Behzad Razavi's CMOS before designing these kind of circuitry.
you need to learn about fundamental CMOS design methods and concepts.
1 members found this post helpful.

24th August 2017, 03:02 #48
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24th August 2017, 03:27 #49

24th August 2017, 03:48 #50
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Re: Gyrator implementation of chip inductor
http://ngspice.sourceforge.net/docs/...al.pdf#page=81
Amplitude of sine wave = 1V

24th August 2017, 04:12 #51
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Re: Gyrator implementation of chip inductor
Last edited by Ata_sa16; 24th August 2017 at 04:19.

24th August 2017, 05:37 #52
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Re: Gyrator implementation of chip inductor
@Ata_sa16
Ok, I have changed it to use pulse() accordingly, but I think the transient simulation plot makes me think that pulse() stimulus for Vtest is not suitable to CMOS inverter used as gmcell.
https://github.com/noqsi/gnetspice...ard#simulation

24th August 2017, 05:37

25th August 2017, 10:20 #53
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Re: Gyrator implementation of chip inductor
Could anyone help with these two questions ?
https://www.reddit.com/r/chipdesign/...r_ota/dm0sm72/
https://sourceforge.net/p/ngspice/di...25&page=2#67d9

26th August 2017, 08:36 #54
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Re: Gyrator implementation of chip inductor

2nd September 2017, 15:49 #55
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Re: Gyrator implementation of chip inductor
@Ata_sa16
This is a gyrator made up of two gmcells (X1 and Gm2 blocks), transforming CL into active inductor.
equivalent inductance value, Leq = CL / [(gm of X1 circuit block)*(gm of Gm2 circuit block)]
Should I simulate the two respective values of overall transconductance of Gm2 and X1 circuit blocks independently or inside the larger circuit below with the presence of Cs and CL ?
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