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Questions tagged [solid-state-devices]

Refers to solid devices built on silicon wafers or ceramic substrate. Materials used could be silicon, germanium or gallium arsenide with copper conductors and oxide based insulators. Doping is the addition of performance enhancements compounds such as gold or germanium. Includes transistors of all types and logic, analog and special purpose devices such as CCD sensors. When done devices are sealed with plastic or ceramic compounds.

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Why does it seem like the ideal photodiode model leads to a violation of conservation of energy?

Short version of my question: Roughly speaking, the output power from a properly biased ideal photodiode feeding a resistor is quadratic with the optical input power, with seemingly no limit. So at ...
Kevin Brant's user avatar
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Process compatibility between a non-planar avalanche photodiode and planar CMOS at 0.130μm process technology node

I plan to integrate a non-planar P⁺⁺/i/P⁺/N⁺⁺ avalanche photodiode (APD) array with a peripheral control circuit (e.g., trans-impedance amplifier, analog-to-digital converter, and quenching circuit) ...
Amita Rawat's user avatar
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2 answers
83 views

Why does light doping imply a large temperature coefficient?

In a discussion about how one can make integrated resistors in a given IC technology, Gray, Hurst, Lewis, and Meyer (Analysis and Design of Analog Integrated Circuits) remark that if we want to use a ...
EE18's user avatar
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Limit of applicability of "quasistatic"/capacitive picture of devices

When analyzing the transitories associated with switching in semiconductor devices, in textbook treatments one often sees the time dependence considered by including (potentially nonlinear) capacitors ...
EE18's user avatar
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Why doesn't side diffusion raise resistance of an integrated resistor?

Consider forming an integrated resistor by diffusion of n+ dopants down into some p- substrate (the corresponding pn junction is reverse biased during operation). Let \$W,L,t\$ be the width, length, ...
EE18's user avatar
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6 answers
353 views

How on Earth can a solid state relay be constructed?

Relays are very handy components. Relays allow current to both directions on the controlled load circuit so they can be used for both AC and DC. However, relays have a finite lifetime if connected/...
juhist's user avatar
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4 votes
2 answers
818 views

Why are drain and source not actually perfectly symmetric?

In textbook treatments, one has that the source and drain of a MOSFET are completely symmetrical and therefore interchangeable -- the distinction is only made by which is at a higher voltage in the ...
EE18's user avatar
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On different well processes (reasons)

My textbook (Weste and Harris's CMOS VLSI Design) is trying to explain to me the difference between n-well, twin-well, and triple-well processes. My question here is about the reasons why we want to &...
EE18's user avatar
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Justification for equivalent gate capacitance simplification in digital circuits

A MOSFET is, in reality, a four-terminal device with capacitances between each pair of terminals: These capacitances are, of course, the standard MOSFET intrinsic and extrinsic differential ...
EE18's user avatar
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4 answers
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Why do we usually operate well into strong inversion?

In textbooks like the venerable Gray and Hurst or in contexts like my introductory analog design class, it was always emphasized that with MOSFETs we always want our designs to obey some constraint ...
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Do LEDs turn on because of heat? [duplicate]

I was watching one of my seniors soldering a few SMD LEDs on one of his power converters. He touched the iron on the anode of one of the LEDs and it glowed. I think it is because of thermal generation....
Jonathan_the_seagull's user avatar
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Understanding thermal instability breakdown in pn junctions

I am currently reading Sze (Physics of Semiconductor Devices, 3e, Chapter 2.4.1) and am trying to understand his discussion of thermal instability breakdown/runaway in pn junctions. I have also ...
EE18's user avatar
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Why do PMOS suffer a worse body effect than NMOS?

Gray, Hurst, Lewis, and Meyer give the following discussion around PMOS transistors which I followed except for the sentence which reads: Good use can be made of this fact in analog circuits to ...
EE18's user avatar
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1 answer
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Confusion about why pn junction discussion insensitive to doping variations faster than Debye length

Sze (Physics of Semiconductor Devices, 3e) gives the following discussion which relates to how equilibrium electric fields/equilibrium potential build-up at thermal equilibrium are related to doping ...
EE18's user avatar
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Does \$\phi_{bi}\$ depend on applied voltage in non-uniformly doped junctions?

Consider a linearly graded junction $$N_D - N_A = ax$$ for some grading constant \$a\$. Using the standard simplifying assumptions one finds that the depletion region extent is $$x_{SCR} = \left[\frac{...
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Inversion vs accumulation mode MOS capacitor

Edit Both FETs are the same PFET with the same dimensions. I wanted to check the capacitance of a MOS capacitor vs its orientation. I expected the gate low orientation to have greater capacitance ...
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Why is length scaling equivalent to series transistors?

In what follows, I am neglecting all non-idealities. All transistors are assumed to obey the first-order, long-channel IV characteristics. My VLSI text (Weste and Harris) claims that, given these ...
EE18's user avatar
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1 vote
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Why do series NMOS do better than a single NMOS from a delay perspective?

My VLSI text (Weste and Harris) writes the following: Transistors in series drop part of the voltage across each transistor and thus experience smaller fields and less velocity saturation than single ...
EE18's user avatar
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Can SP2T RF switches be considered failsafe?

I am looking for a RF switch that is failsafe. For failsafe I mean: a device that defaults to a useful state during total power loss (no supply voltage, no control voltage) for a RF switch, a device ...
Alessandro Cuttin's user avatar
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0 answers
54 views

Solid state RF switch with feedback: does it exist?

I am looking for a solid state RF switch (for example, PIN diode, but not only) that features a feedback of the switch status. For electromechanical RF switches this seems relatively easy to found, ...
Alessandro Cuttin's user avatar
4 votes
3 answers
166 views

Do MOSFETs Share Avalanche Energy?

I understand that MOSFETs act like resistors when they are on, and that is why they share current nicely. (As opposed to diodes and BJT's, which act like voltage sources when they are on, and that is ...
James Strieter's user avatar
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0 answers
49 views

Generating cold plasma using a Piezo Transformer

I am trying to generate cold plasma using a multi layer piezo transformer. My understanding was that it was as simple as applying a 15 Vpp to the transformer, but it did not work. I was trying to ...
HTZ's user avatar
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2 answers
63 views

Will Any SCR Trigger Optically If It Is Exposed To Light?

I read somewhere that all SCR's are photosensitive, in the same way that all diodes emit light, but some are optimized to take advantage of this property while others are not. There is an SCR I want ...
James Strieter's user avatar
1 vote
2 answers
142 views

MOSFET SOA: Why is the max current limit lower for DC case? [duplicate]

Shown above is the academic definition of MOSFET SOA. Rdson limit is not considered as a real limit in most academic texts - that's ok- understandable. But why is the max drain current limit different ...
Dynamic_equilibrium's user avatar
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1 answer
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Is It Possible To Choose a Higher Holding Current When Designing SCR?

I'm looking at this data sheet: SCR data sheet on Digikey This device seems perfect for what I want to do, with 1 exception: The holding current is way too low. Various forums have suggested that (on ...
James Strieter's user avatar
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0 answers
92 views

Simulating an equivalent circuit model of a laser in LTspice, how does it solve this circuit?

I want to know how LTspice solves this circuit as there are node voltage (vj) dependent current sources (Ist and Isp) present in this circuit. Also, I had an unknown parameter, Ne, whose value I ...
L1234's user avatar
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4 votes
1 answer
532 views

What percentage of a DRAM cell size is occupied by the transistor and/or the capacitor?

Assuming that we have a 1T1C DRAM cell manufactured at 22nm process. Based on this we can have an idea about the cell area (0.026 um^2 in this case). However, I could not find specific information ...
Arkoudinos's user avatar
2 votes
1 answer
61 views

For sufficiently low duty cycle, can you get away with driving SCR above rated current as long as A^2 * s are maintained?

I'm wondering if the A^2-s rating of an SCR is what ultimately decides whether a given current for a given time is okay, even if the data sheet does not list such a number. For instance, right now I ...
James Strieter's user avatar
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1 answer
261 views

What types of power rail are there in an integrated circuit?

I understand that power rails provide the energy required for a circuit to function. Intuition tells me there must be at least two types of rail, one providing power and another taking it away. But I ...
Connor's user avatar
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3 votes
1 answer
254 views

What is equilibrium carrier concentration in a semiconductor? Is it material specific? How to calculate it?

Is equilibrium carrier concentration dependent on doping density? If it is, then how to know how much the doping density should be for a particular semiconductor device?
L1234's user avatar
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1 vote
1 answer
84 views

Switching low voltage with high accuracy

To do some discharge tests, I want to connect 1.5 V batteries to very low resistances for a short amount (10 - 200 ms) of time, then have them disconnected for at least a couple of seconds. What would ...
JSz's user avatar
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1 vote
1 answer
172 views

RF power amplifier tuning of output stage tube vs transistor

In the old days with vacuum tubes for power amplifiers we carefully tuned the output stage, dipped the plate current to get maximum efficiency. Looking at todays transistor PA circuits I don't see a ...
user3799318's user avatar
0 votes
1 answer
147 views

Simulated speaker dummy load for solid state

This is specific for 6 string electric guitar amplifiers. The convention appears to be use a resistor equal to the nominal DCR of the intended speaker load, usually 4 or 8 Ω. What I have found out was,...
ITPhoenix's user avatar
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2 answers
271 views

Does the gate leakage current increase or decrease the drain current in MOSFET?

I know that the gate leakage means that the electrons are injected from the gate metal into the channel, therefore the conventional current direction is from channel to the gate. From KCL, I think ...
user207787's user avatar
1 vote
1 answer
122 views

How to draw power from one of two sources according to priority, with indication for used source?

If two 5V power sources exist, one being always on and the other not (such as an ATX powersupply's standby 5V and "on" 5V rails), how could I draw power only from the "on" rail ...
John Schultz's user avatar
5 votes
2 answers
1k views

What is exactly a "stabistor"? How does it work and how is it constructed?

Today, for the first time in my life I encountered the term "stabistor". From a quick search on the Internet it seems it's a two-terminal diode-like semiconductor device used to regulate low ...
LorenzoDonati4Ukraine-OnStrike's user avatar
2 votes
1 answer
689 views

Why do SSDs have a limited lifespan?

Why do solid-state drives even have a limited number of read/write cycles, usually 100,000-300,000 cycles? For hard-disk drives, it is understandable why they wear out. That is because they have ...
CoastCity Lapse 00crashtest's user avatar
5 votes
1 answer
408 views

Semiconductors: electrons more mobile than holes despite being heavier?

I apologize if this is a very basic question. But I have always known it to be true that in Silicon, electrons have higher mobility than holes. From my semiconductor physics classes in first year, the ...
First User's user avatar
0 votes
4 answers
545 views

How do I (can I) replace the relay in this circuit with a transistor?

Background I have the following circuit and it has been working for years. Please note that the circuit drawing may not match the real circuit exactly, but it is just a diagram to attempt to get my ...
raddevus's user avatar
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6 votes
4 answers
3k views

What prevents MOSFET drain-to-gate leakage current?

What in the structure of a MOSFET prevents leakage current flowing from the drain to the gate of a MOSFET when the drain is at a higher potential than the gate? I am assuming that drain-to-gate ...
mamawmaw's user avatar
4 votes
3 answers
639 views

Potential distribution in MOSFET

Let us assume that an NMOSFET has its source, drain and substrate grounded therefore VDS and VSB=0 V . We apply a gate voltage VGS=2 V and I want to know how this potential is distributed as we move ...
user14598090's user avatar
0 votes
1 answer
94 views

Trouble with body effect physics

I’m struggling to understand why a negative voltage applied to the bulk contact of an n-type MOSFET increases the threshold voltage. I read other similar questions and I get that the negative voltage ...
ale_zec's user avatar
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1 vote
0 answers
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Calculating capacitance in a MOS capacitor

A \$MOS\$ capacitor with \$t_{ox}=10nm\$ has an \$n^{+}\$ polysilicon gate electrode and an \$n\$-type substrate with doping concentration \$ N_D=10^{15}/cm^3\$ . Given: \$V_T=kT/q=26mV\$, \$\...
user600016's user avatar
-1 votes
2 answers
412 views

Is it possible for an SoC to have a built-in SSD?

Is it possible to have an SoC that includes an SSD on-chip, or are there technical constraints that prevent that? What are those technical constraints, if any?
steventrouble's user avatar
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1 answer
1k views

MOS Capacitor band diagram question

In a MOS system, is the energy offset between metal/oxide or semiconductor/oxide always the same regardless of the gate voltage applied? In other words, are A and B in the diagram above always the ...
user207787's user avatar
0 votes
1 answer
40 views

Energy band diagram of a polar material

For a single piece of a polar material (ex. GaN, AlN, etc), there exists a constant electric field inside the material due to the bound charges at the surface. Above figure shows the resulting band ...
user207787's user avatar
2 votes
1 answer
106 views

How to power this RF microwave solid state switch

I have the following RF switch: After googling for several hours, I have found that it is a solid state switch, from DC to 26.5GHz. I've also been able to test that between the golden plated female ...
MikeTeX's user avatar
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2 votes
2 answers
1k views

Why does the majority carrier concentration near the junction not decrease under forward bias? (PN junction)

We see that the current due to the majority carrier decreases near the junction as shown above, which means the majority carrier concentration should also decrease since the diffusion current is given ...
user207787's user avatar
4 votes
2 answers
4k views

Why are quasi-Fermi levels flat across the depletion region in a pn diode under forward bias?

Why is the quasi-Fermi level flat across the depletion region in a pn diode under forward bias? I get that EFn decreases on the p-type side and EFp decreases on the n-type side due to recombination, ...
user207787's user avatar
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0 answers
127 views

Secondary Coil Malfunction in an SSTC Circuit

I’ve designed an SSTC circuit which is based on a different topology and I wanted to accomplish it in real life. The circuit is operating at approximately 1.5 MHz during resonance and inherently, the ...
Karakoncolos's user avatar