26 Threads found on edaboard.com: Positive Pole
Yes - such a capacitor between C and E in common-B configuration provides positive feedback and, thus, increases the input impedance for rising frequencies.
This can be also described by the term "invers (negative) MILLER effect". However, at the same time, the gain decreases (C parallel to Rc).
Why do you expect an RHP pole?
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Elementary Electronic Questions :: 08-25-2016 10:06 :: LvW :: Replies: 2 :: Views: 1012
1 st order are inherently stable but noisy
2nd order are less noisy and C2/C1 ratio affects pole position
3rd order are inherently unstable with >180 deg phase shift and negative feedback becomes positive feedback.
Rule of Thumb ratios help provide LPF additional rolloff using lag-lead filters to give phase margin at unity gain and may have
Analog Circuit Design :: 07-29-2015 15:30 :: SunnySkyguy :: Replies: 2 :: Views: 667
As I recall the negative feedback loop may have zeros, but the transfer function of P(s)/Q(s) for the positive input is often 1/(1+H(s)) thus the overall gain never reaches zero unless H(s) =-1
Digital Signal Processing :: 11-13-2014 16:31 :: SunnySkyguy :: Replies: 2 :: Views: 795
Hi guys, I have a problem about the stability of positive feedback.
Let's say for a opam, it has 3 poles (LHP) at DC and 2 zeros (LHP) at wz. Then at DC, its phase shift is -270 degree , and at wz, its phase shift is -180 degree. At wz, its gain is 4.
Then we connect the opam in a unity gain negative feedback structure.
The phase margin of
Analog Circuit Design :: 11-03-2014 22:15 :: kerrytang :: Replies: 15 :: Views: 3075
If Real(s1) and Real (s2) is positive, the circuit will absolutely be unstable regarding to Hurwitz criteria.
RF, Microwave, Antennas and Optics :: 10-30-2014 20:17 :: BigBoss :: Replies: 6 :: Views: 1065
please leave this figure it is not that clear, refer to the first one of my post with the separated results , the curve with the DC gain of 81 is the circuit with the positive feedback
the second graph with the DC gain of 74 is without the positive feedback
I dont know what you mean to say by my self, I am using mentor gr
Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 02-05-2013 19:34 :: LvW :: Replies: 21 :: Views: 2980
You'll determine stability by analyzing the loop gain magnitude and phase characteristic. For the simple case of monotone magnitude characteristic, a positive phase margin implies stability. A considerably larger phase margin will be required for acceptable time domain behaviour, however.
Strictly speaking, an OP with only two poles and real fee
Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 11-25-2012 22:50 :: FvM :: Replies: 7 :: Views: 3032
If you have a transistor with components connected from its collector circuit to its base circuit, its negative feedback, because when th collector signal goes positive, the base signal is going negative. If however you change the components so they introduce greater then 180 degrees phase shift and the transistor has a gain greater then 1. The cir
Elementary Electronic Questions :: 05-16-2012 16:20 :: chuckey :: Replies: 7 :: Views: 730
Yes, I mean the Vcc, the + pole of the battery, call it how you want! Vss is how microchip calls it in the datasheets, that's why I used it like this.
I never saw the positive supply node named Vss in a datasheet. If pin 2 is the positive supply node and pin 1 more negative tahn pin 2, you'll expect a PMOS FET like Si2323.
Elementary Electronic Questions :: 01-24-2012 23:19 :: FvM :: Replies: 9 :: Views: 2465
What is the inverse laplace transform of 1/(s+a)? What do you think happens when a is positive?
Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 12-30-2011 10:03 :: checkmate :: Replies: 2 :: Views: 522
Grounded load only means the the load is connected one end to a ground ..
In this case the current source sources current from the positive pole to negative pole (ground) through a load ..
If you use current source a current limiting resistor is not required ..
See:
A Constant Current Source
Elementary Electronic Questions :: 10-14-2010 04:05 :: IanP :: Replies: 2 :: Views: 2311
That's not possible! Q factor by definition is always is positive. Check for calculation error.
Analog Circuit Design :: 05-05-2010 07:19 :: LvW :: Replies: 20 :: Views: 7466
Thanks, flatulent.
I want to realize a rising phase vs frequency, so it need a positive pole, and negative zero. But in many paper and book, there are a negative pole and positive zero.
Analog Circuit Design :: 10-01-2009 08:30 :: rambus_ddr :: Replies: 5 :: Views: 1070
There no positive pole or negative pole concept in the alternative current, since it is continuously changing. It doesn't matter how you plug your AC since both poles will be having the same function.
In the other hand, in DC DOES matter the polarization, since it is a constant voltage. From the + pin, you will have (...)
Elementary Electronic Questions :: 09-30-2008 07:51 :: halls :: Replies: 4 :: Views: 4044
It means you have peaking caused by a conjugated pole pair around 105 MHz. This pair is probably unwanted and can be caused by a feedforward path or positive feedback at that frequency. If you used feedback, is your phase margin large enough? You might be close to instability at 105MHz.
Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 01-11-2008 10:05 :: ce :: Replies: 2 :: Views: 852
poles and zeroes introduce phase shift frequency dependant. So at some frequencies the negative feedback can turn to positive feedback
Elementary Electronic Questions :: 01-03-2008 13:29 :: cesare :: Replies: 5 :: Views: 13748
what you see are more poles at f=1e8 . Each pole adds phase shift, but phase shift larger than minus 180 degrees is subtracted from plus 180 degrees (kinda fuzzy explanation). Basically what you are seeing is that the phase shift is clipping.
Also the magnitude shows a positive peek as well again, this indicates some zeros at that point.
Hope
Analog Circuit Design :: 11-02-2007 15:14 :: demodb :: Replies: 1 :: Views: 2533
I have derived a transfer function containing 3 poles. All the coefficients are positive but from matlab analysis, there is one LHP real pole and a pair of RHP complex poles. Previously, I have a misconception that a cubic equation having all +ve coeff will yield all poles in the LHP. Could some mathematics (...)
Analog Circuit Design :: 05-22-2007 14:02 :: pseudockb :: Replies: 3 :: Views: 3920
If I am not wrong, I read that the B+ comes from the Battery positive connector/pole used in old vacuum tubes/valve operated equipment (radios).
Elementary Electronic Questions :: 05-07-2007 11:52 :: rkodaira :: Replies: 3 :: Views: 911
Dear All,
why a positive zeros in a transfer function creates negative phase shift (just as a pole) ?
Thanks for answering.
Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 02-22-2007 17:50 :: Tahar :: Replies: 1 :: Views: 745