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Band gap reference
Play with the resistor. The resistor sets the amplification of the PTAT Voltage. Means you can move the maximum of the Bandgap refrence (Vbe-V_PTAT=Vbg). Normal people set the maximum of the Vbg voltage to 27 C°. You can do a parametric simulation (with Rpn as paramtere) you...
I looked into the Datasheet. I thinke you have to fit your model by hand, even if you know the correct W and L.
The Vth can go from 0.8 V- 1.8V ! The model uses the nominal value 1.3V. I would try to measure Vth from the real MOS to see if Vth is your problem.
I woulded do a two stage, because of compensation and power. I would go for a singel stage folded cascode, you should get the swing of 2V, if needed gain boosting to regain Gain if you lose to much at the corners.
Added after 1 minutes:
I mean wouldn't sorry
Hi look for the paper from C. C. Enz and G. C. Temes "Circuit techniques for reducing the effects of op-amp imperfections: autozeroing, correlated double sampling, and chopper stabilization". It is good summary. Or papers from delft U. they do also a lot of this stuff
how to calculate amps
Good luck, if you don't make the circuit simpler. I've done a telescopic (without the Gain Boosters), and I used the matlab symbolic tool box. This was a transfere function, big very big. So I would sugest, reduce the circuit to its important parts (like input pair and...
cmos opamp
Don’t use a two stage approach; you will burn too much current in the second stage.
Unity Gain Bandwidth = 500 MHz => for stability second pole should be around 1.5 GHz!!!!!
Second Pole = gm(second stage)/(2*pi*Cload), believe me that will cost current.
Normally a folded cascade...
Accurate resistor
Don't use resistors, if accuracy is needed. For example if you trie to move the zero in a miller compensation with a resistor you will run into problems. Accuracy is not the only problem, temp variations are also a bad habbit of such things.
spectre dc analysis
You can find the answer in Behzad Razavis book (”Design of Analog CMOS Integrated Circuits”, McGraw-Hill 2001)
Basically the reason is a none linear doping which fights the DIBL (drain-induced barrier
lowering) effect. Is needed for short channel transistors
how to find the threshold voltage of a transistor
You can try to implement you optimization algorithm into Ocean, here you can automate the howl thing and you have the chance to grab the v_th from the operating point analysis.
Joyes statement is correct; the equation you are using is for differential gain. But you are using it as an single ended version, hence the DC gain is twice the differential gain.
cadence optimization dc
You can find the threshold voltage under the DC operating point information. But, I think that information will be useless for optimization, because the threshold voltage depends on the channel length for short channel processes (Vth is not a constant).
Actually I...
First I don’t understand why M14 should only has a gm/Id= 4, because it is cascode and I would expected a much higher gm/Id like 12 or 14. I think that’s the problem, for gm/Id=4 you need a very large Vov and this can’t be delivered from M12.
The coscod bulk connection is also a problem usally...
gm of MOSFET
I think it is impossible to model gds (Ro) with one lambda factor. You can plot gds with a simulator and you will see that is hopeless. All calculation (in a short channel process) with the square law equations will be off big time. I use the gm/Id method and I’m very happy with...
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