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Type: Posts; User: htg

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1. ## Thread: Transition frequency fT of a transistor - definition

by htg
Replies
1
Views
297

### Closed: Transition frequency fT of a transistor - definition

Is it the frequency at which power gain decreases by 3dB or frequency at which gain drops to unity? Does current gain count here or power gain?
2. ## Thread: Did early power MOSFETs have body diode?

by htg
Replies
1
Views
224

### Closed: Did early power MOSFETs have body diode?

Also I would like to know if small-signal MOSFETs have body diode.
3. ## Thread: Cut-off current through an N-channel power MOSFET with negatively charged gate

by htg
Replies
6
Views
366

### Closed: Re: Cut-off current through an N-channel power MOSFET with negatively charged gate

In the response of dick freebird above there is the statement:

"GIDL (gate induced drain leakage) is a thing in some types
of MOSFETs (though I've seen it more in integrated, plain
FETs). That...
4. ## Thread: Cut-off current through an N-channel power MOSFET with negatively charged gate

by htg
Replies
6
Views
366

### Closed: Re: Cut-off current through an N-channel power MOSFET with negatively charged gate

I am clearly asking about MOSFETs, so gate current should be much smaller than drain current.
5. ## Thread: Optimally Accurate 28-bit A/D conversion

by htg
Replies
8
Views
496

### Closed: Re: Optimally Accurate 28-bit A/D conversion

New production techniques may be necessary - e.g. all Cu ICs including leads, microwelding. For a given A/D converter it is possible to compensate for nonlinearity.
6. ## Thread: Optimally Accurate 28-bit A/D conversion

by htg
Replies
8
Views
496

### Closed: Re: Optimally Accurate 28-bit A/D conversion

What is the fastest 28-bit A/D converter?
7. ## Thread: Optimally Accurate 28-bit A/D conversion

by htg
Replies
8
Views
496

### Closed: Optimally Accurate 28-bit A/D conversion

If I want e.g. 28-bit accurate A/D conversion by multiple conversions and averaging, what is the optimal A/D converter - so that total conversion time is the shortest?
8. ## Thread: Cut-off current through an N-channel power MOSFET with negatively charged gate

by htg
Replies
6
Views
366

### Closed: Cut-off current through an N-channel power MOSFET with negatively charged gate

How low can such current be?
9. ## Thread: Are there really ferrites for multi-GHz frequencies?

by htg
Replies
3
Views
522

### Closed: Are there really ferrites for multi-GHz frequencies?

Supposedly Hexaferrite (barium ferrite) works at such frequencies. But I have found information that it has permeability = 1.1, so it is not much gently speaking. If there are such high-frequency...
10. ## Thread: Are there really ferrites for multi-GHz frequencies?

by htg
Replies
3
Views
522

### Closed: Where Can I buy Transformer Core Ferrites for Frequencies ABOVE 200 MHz ?

I know of 200 MHz ferrites e.g. by National Magnetics Group. Are there any ferrites good for transformers above 200 MHz?
11. ## Thread: Permittivity of Ferrites

by htg
Replies
2
Views
920

### Closed: Permittivity of Ferrites

Various sources give different information regarding permittivity of ferrites.
They seem to agree that epsr = 10 to 20 for NiZn ferrites, but for MnZn ferrites they quote values from 10 to 300.
I...
12. ## Thread: Hysteresis material constant

by htg
Replies
0
Views
307

### Closed: Hysteresis material constant

I would like to know what values of nB I can expect for NiZn ferrites and for MnZn ferrites (*10^-6/mT). Also, I want to know what B value I should use in the equation tan(delta) = nB*mur*B - should...
13. ## Thread: What if the skin depth is of the order of 100 pm?

by htg
Replies
5
Views
835

### Closed: What if the skin depth is of the order of 100 pm?

If the skin depth is subatomic, it seems that resistance will not increase when compared with the situation when skin depth = atomic diameter.
14. ## Thread: Inductance of not very long stretch of litz wire

by htg
Replies
2
Views
459

### Closed: Re: Inductance of not very long stretch of litz wire

Imagine two metal balls at ends of the short stretch of litz wire. The balls are unipolar capacitors.
Will this system have approximately the same resonant frequency as a similar system made with...
15. ## Thread: Inductance of not very long stretch of litz wire

by htg
Replies
2
Views
459

### Closed: Inductance of not very long stretch of litz wire

Probably twisting increases inductance as compared to solid wire. I would like to know to what extent.
16. ## Thread: Electrodynamics, wave equation, velocity of waves

by htg
Replies
9
Views
5,877

### Closed: Re: Electrodynamics, wave equation, velocity of waves

1) Photons do not exist at all. Look at lower and upper limits of frequency for photoelectric effect.
2) I am asking about phase velocity of a magnetically longitudinal, electrically torsional wave...
17. ## Thread: Electrodynamics, wave equation, velocity of waves

by htg
Replies
9
Views
5,877

### Closed: Re: Electrodynamics, wave equation, velocity of waves

If you believe in photons, then you should look at the TRUE characteristics of photoelectric effect: it is a resonance phenomenon, it has lower and upper limit of frequency.
18. ## Thread: Telegrapher's equations - How can one obtain wave equations

by htg
Replies
0
Views
1,439

### [SOLVED]Closed: Telegrapher's equations - How can one obtain wave equations

How can we start from

dV/dx = - L dI/dt
and
dI/dx = -C dV/dt

to obtain a pair of wave equations?

- - - Updated - - -
19. ## Thread: Electrodynamics, wave equation, velocity of waves

by htg
Replies
9
Views
5,877

### Closed: Re: Maxwell's equations - is there a bigger picture?

I give clear examples where Maxwell's equations are violated.
Maxwell's equations are supposed to be valid in any situation which can
be encountered in Electrodynamics. There are no hidden...
20. ## Thread: Electrodynamics, wave equation, velocity of waves

by htg
Replies
9
Views
5,877

### Closed: Electrodynamics, wave equation, velocity of waves

1) div(B)=0 and div(E)=0 are true only in magnetostatic and electrostatic situations, otherwise they can be violated (consider a Gaussian beam of EM waves).
2) Maxwell's extension of the Ampere's...
21. ## Thread: 1 ns switching time power transistor - how can I find such?

by htg
Replies
3
Views
1,208

### Closed: 1 ns switching time power transistor - how can I find such?

I want to find a 10A, 100V, 1 ns switching time transistor. Google search only leads to much slower transistors.
Can you help me?
22. ## Thread: Electrodynamics, wave equation, velocity of waves

by htg
Replies
9
Views
5,877

### Closed: Maxwell's equations - is there a bigger picture?

Maxwell's Equations sometimes are satisfied and sometimes are not satisfied. Examples:

1) Gauss' Law can be violated e.g. by a Gaussian beam of EM waves.
2) Ampere's law leads to the equation...
23. ## Thread: Maxwell's equations for a magnetically longitudinal wave

by htg
Replies
16
Views
2,154

### Closed: Maxwell's equations for a magnetically longitudinal wave

Consider a magnetically longitudinal near-field wave in a ferrite rod.
Maxwell's equations lead to grad(div(B)) - ΔB = - µ*ε*(d^2 B/dt^2).
This is not non-trivially satisfied e.g. by B(x,y,z,t) =...
24. ## Thread: Violation of Gauss Law

by htg
Replies
5
Views
1,177

### Closed: Re: Violation of Gauss Law

Polarization of the beam is vertical, so lines of E field will be in vertical planes.
25. ## Thread: Violation of Gauss Law

by htg
Replies
5
Views
1,177

### Closed: Re: Violation of Gauss Law

Flux density will quickly decrease as we go up from the axis of the beam.
The side walls should be aligned with the lines of the E field so that the flux
through each of them is zero. Thanks to...
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