Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

MOS varactors for High Frequency

Status
Not open for further replies.

umberabbas

Member level 1
Member level 1
Joined
Mar 24, 2017
Messages
32
Helped
0
Reputation
0
Reaction score
0
Trophy points
6
Activity points
285
I am trying to characterize MOS varactors (NMOS) to get S-parameters along with the CV-curve for this circuit. However, I am not getting a suitable result. Please have a look and point out the mistake.
MOS_vrac.pngS_para.png
 

You'd better connect NMOS substrates to GND, not to VDD. In this latter case you just generate a forward polarized pn-junction between substrate & MOS channel.
 

Also, your test-bench is wrong.Review it..
 

So I modified the test bench as shown below with the results attached. Is this the correct method for a MOS transistor to be tested as a MOS varactor?

*The inductor value is 1pH.

Here is the netlist

******************
DC Analysis `dcOp'
******************
Important parameter values:
reltol = 1e-03
abstol(V) = 1 uV
abstol(I) = 1 pA
temp = 27 C
tnom = 27 C
tempeffects = all
gmindc = 1 pS
Convergence achieved in 8 iterations.
Total time required for dc analysis `dcOp': CPU = 3 ms, elapsed = 3.39508 ms.
Time accumulated: CPU = 339.948 ms, elapsed = 2.42305 ks (40m 23.1s).
Peak resident memory used = 26.4 Mbytes.

dcOpInfo: writing operating point information to rawfile.

***********************************
DC Analysis `dc': Vtune = (-2 -> 2)
***********************************
Important parameter values:
reltol = 1e-03
abstol(V) = 1 uV
abstol(I) = 1 pA
temp = 27 C
tnom = 27 C
tempeffects = all
gmindc = 1 pS
dc: Vtune = -1.5 (12.5 %), step = 500e-03 (12.5 %)
dc: Vtune = -1 (25 %), step = 500e-03 (12.5 %)
dc: Vtune = -500e-03 (37.5 %), step = 500e-03 (12.5 %)
dc: Vtune = 0 (50 %), step = 500e-03 (12.5 %)
dc: Vtune = 500e-03 (62.5 %), step = 500e-03 (12.5 %)
dc: Vtune = 1 (75 %), step = 500e-03 (12.5 %)
dc: Vtune = 1.5 (87.5 %), step = 500e-03 (12.5 %)
dc: Vtune = 2 (100 %), step = 500e-03 (12.5 %)
Total time required for dc analysis `dc': CPU = 9.998 ms, elapsed = 10.6552 ms.
Time accumulated: CPU = 362.943 ms, elapsed = 2.42308 ks (40m 23.1s).
Peak resident memory used = 26.4 Mbytes.


****************************************************
S-Parameter Analysis `sp': freq = (40 GHz -> 80 GHz)
****************************************************
sp: freq = 41 GHz (2.5 %), step = 1 GHz (2.5 %)
sp: freq = 42 GHz (5 %), step = 1 GHz (2.5 %)
sp: freq = 43 GHz (7.5 %), step = 1 GHz (2.5 %)
sp: freq = 44 GHz (10 %), step = 1 GHz (2.5 %)
sp: freq = 45 GHz (12.5 %), step = 1 GHz (2.5 %)
sp: freq = 46 GHz (15 %), step = 1 GHz (2.5 %)
sp: freq = 47 GHz (17.5 %), step = 1 GHz (2.5 %)
sp: freq = 48 GHz (20 %), step = 1 GHz (2.5 %)
sp: freq = 49 GHz (22.5 %), step = 1 GHz (2.5 %)
sp: freq = 50 GHz (25 %), step = 1 GHz (2.5 %)
sp: freq = 51 GHz (27.5 %), step = 1 GHz (2.5 %)
sp: freq = 52 GHz (30 %), step = 1 GHz (2.5 %)
sp: freq = 53 GHz (32.5 %), step = 1 GHz (2.5 %)
sp: freq = 54 GHz (35 %), step = 1 GHz (2.5 %)
sp: freq = 55 GHz (37.5 %), step = 1 GHz (2.5 %)
sp: freq = 56 GHz (40 %), step = 1 GHz (2.5 %)
sp: freq = 57 GHz (42.5 %), step = 1 GHz (2.5 %)
sp: freq = 58 GHz (45 %), step = 1 GHz (2.5 %)
sp: freq = 59 GHz (47.5 %), step = 1 GHz (2.5 %)
sp: freq = 60 GHz (50 %), step = 1 GHz (2.5 %)
sp: freq = 61 GHz (52.5 %), step = 1 GHz (2.5 %)
sp: freq = 62 GHz (55 %), step = 1 GHz (2.5 %)
sp: freq = 63 GHz (57.5 %), step = 1 GHz (2.5 %)
sp: freq = 64 GHz (60 %), step = 1 GHz (2.5 %)
sp: freq = 65 GHz (62.5 %), step = 1 GHz (2.5 %)
sp: freq = 66 GHz (65 %), step = 1 GHz (2.5 %)
sp: freq = 67 GHz (67.5 %), step = 1 GHz (2.5 %)
sp: freq = 68 GHz (70 %), step = 1 GHz (2.5 %)
sp: freq = 69 GHz (72.5 %), step = 1 GHz (2.5 %)
sp: freq = 70 GHz (75 %), step = 1 GHz (2.5 %)
sp: freq = 71 GHz (77.5 %), step = 1 GHz (2.5 %)
sp: freq = 72 GHz (80 %), step = 1 GHz (2.5 %)
sp: freq = 73 GHz (82.5 %), step = 1 GHz (2.5 %)
sp: freq = 74 GHz (85 %), step = 1 GHz (2.5 %)
sp: freq = 75 GHz (87.5 %), step = 1 GHz (2.5 %)
sp: freq = 76 GHz (90 %), step = 1 GHz (2.5 %)
sp: freq = 77 GHz (92.5 %), step = 1 GHz (2.5 %)
sp: freq = 78 GHz (95 %), step = 1 GHz (2.5 %)
sp: freq = 79 GHz (97.5 %), step = 1 GHz (2.5 %)
sp: freq = 80 GHz (100 %), step = 1 GHz (2.5 %)
Accumulated DC solution time = 0 s.
Intrinsic sp analysis time = 0 s.
Total time required for sp analysis `sp': CPU = 3 ms, elapsed = 3.77607 ms.
Time accumulated: CPU = 365.943 ms, elapsed = 2.42308 ks (40m 23.1s).
Peak resident memory used = 26.4 Mbytes.


**************************************************
AC Analysis `ac': freq = 60 GHz, Vtune = (-2 -> 2)
**************************************************
ac: Vtune = -1.84 (4 %), step = 80e-03 (2 %)
ac: Vtune = -1.76 (6 %), step = 80e-03 (2 %)
ac: Vtune = -1.68 (8 %), step = 80e-03 (2 %)
ac: Vtune = -1.6 (10 %), step = 80e-03 (2 %)
ac: Vtune = -1.52 (12 %), step = 80e-03 (2 %)
ac: Vtune = -1.44 (14 %), step = 80e-03 (2 %)
ac: Vtune = -1.36 (16 %), step = 80e-03 (2 %)
ac: Vtune = -1.28 (18 %), step = 80e-03 (2 %)
ac: Vtune = -1.2 (20 %), step = 80e-03 (2 %)
ac: Vtune = -1.12 (22 %), step = 80e-03 (2 %)
ac: Vtune = -1.04 (24 %), step = 80e-03 (2 %)
ac: Vtune = -960e-03 (26 %), step = 80e-03 (2 %)
ac: Vtune = -880e-03 (28 %), step = 80e-03 (2 %)
ac: Vtune = -800e-03 (30 %), step = 80e-03 (2 %)
ac: Vtune = -720e-03 (32 %), step = 80e-03 (2 %)
ac: Vtune = -640e-03 (34 %), step = 80e-03 (2 %)
ac: Vtune = -560e-03 (36 %), step = 80e-03 (2 %)
ac: Vtune = -480e-03 (38 %), step = 80e-03 (2 %)
ac: Vtune = -400e-03 (40 %), step = 80e-03 (2 %)
ac: Vtune = -320e-03 (42 %), step = 80e-03 (2 %)
ac: Vtune = -240e-03 (44 %), step = 80e-03 (2 %)
ac: Vtune = -160e-03 (46 %), step = 80e-03 (2 %)
ac: Vtune = -80e-03 (48 %), step = 80e-03 (2 %)
ac: Vtune = 0 (50 %), step = 80e-03 (2 %)
ac: Vtune = 80e-03 (52 %), step = 80e-03 (2 %)
ac: Vtune = 160e-03 (54 %), step = 80e-03 (2 %)
ac: Vtune = 240e-03 (56 %), step = 80e-03 (2 %)
ac: Vtune = 320e-03 (58 %), step = 80e-03 (2 %)
ac: Vtune = 400e-03 (60 %), step = 80e-03 (2 %)
ac: Vtune = 480e-03 (62 %), step = 80e-03 (2 %)
ac: Vtune = 560e-03 (64 %), step = 80e-03 (2 %)
ac: Vtune = 640e-03 (66 %), step = 80e-03 (2 %)
ac: Vtune = 720e-03 (68 %), step = 80e-03 (2 %)
ac: Vtune = 800e-03 (70 %), step = 80e-03 (2 %)
ac: Vtune = 880e-03 (72 %), step = 80e-03 (2 %)
ac: Vtune = 960e-03 (74 %), step = 80e-03 (2 %)
ac: Vtune = 1.04 (76 %), step = 80e-03 (2 %)
ac: Vtune = 1.12 (78 %), step = 80e-03 (2 %)
ac: Vtune = 1.2 (80 %), step = 80e-03 (2 %)
ac: Vtune = 1.28 (82 %), step = 80e-03 (2 %)
ac: Vtune = 1.36 (84 %), step = 80e-03 (2 %)
ac: Vtune = 1.44 (86 %), step = 80e-03 (2 %)
ac: Vtune = 1.52 (88 %), step = 80e-03 (2 %)
ac: Vtune = 1.6 (90 %), step = 80e-03 (2 %)
ac: Vtune = 1.68 (92 %), step = 80e-03 (2 %)
ac: Vtune = 1.76 (94 %), step = 80e-03 (2 %)
ac: Vtune = 1.84 (96 %), step = 80e-03 (2 %)
ac: Vtune = 1.92 (98 %), step = 80e-03 (2 %)
ac: Vtune = 2 (100 %), step = 80e-03 (2 %)
Accumulated DC solution time = 0 s.
Intrinsic ac analysis time = 40 ms.
Total time required for ac analysis `ac': CPU = 35.994 ms, elapsed = 36.0401 ms.
Time accumulated: CPU = 401.937 ms, elapsed = 2.42312 ks (40m 23.1s).
Peak resident memory used = 26.4 Mbytes.

modelParameter: writing model parameter values to rawfile.
element: writing instance parameter values to rawfile.
outputParameter: writing output parameter values to rawfile.
designParamVals: writing netlist parameters to rawfile.
primitives: writing primitives to rawfile.
subckts: writing subcircuits to rawfile.

Spara2.pngvaractor2.png
 

So I modified the test bench as shown below with the results attached.
Is this the correct method for a MOS transistor to be tested as a MOS varactor?
Needless to say, Wrong.

There is no response due to too wrong.
https://www.designers-guide.org/Forum/YaBB.pl?num=1519187411

I think you use this sets of MOS Varactors for differential VCO.

Surely consider polarity and bias.

And can you understand mode of S-parameters ?
https://www.edaboard.com/showthread.php?t=367048
https://www.edaboard.com/showthread.php?t=365152

Also surely understand following.
https://www.edaboard.com/showthread.php?t=373118
 
Last edited:

Needless to say, Wrong.

There is no response due to too wrong.
https://www.designers-guide.org/Forum/YaBB.pl?num=1519187411

I think you use this sets of MOS Varactors for differential VCO.

Surely consider polarity and bias.

And can you understand mode of S-parameters ?
https://www.edaboard.com/showthread.php?t=367048
https://www.edaboard.com/showthread.php?t=365152

Also surely understand following.
https://www.edaboard.com/showthread.php?t=373118

Yes it is for the differential VCO.
I need to use these transistors as varactors in my VCO design.
What changes need to be done to get certain results as mentioned. It's urgent :(
 

Yes it is for the differential VCO.
I need to use these transistors as varactors in my VCO design.
What changes need to be done to get certain results as mentioned. It's urgent :(
It is impossible to make corrections since it is too wrong.
 

These MOS transistors can be tested like this or not?
https://www.edaboard.com/showthread.php?t=373118
You can not understand anything at all.

First of all, polarity of MOSFETs are wrong.
Learn very basic hardly.

Use dc_feed instead of 1kohm.
Use dc_block instead of 94fF.

Evaluate Sdd, Scc, Sdc.
If you need only half value for differential drive, evaluate s11 with center node as AC ground.

Center node is a cold node for differential mode.
 

Attachments

  • 180307-205002.png
    180307-205002.png
    12.9 KB · Views: 146
Last edited:

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top