Questions tagged [parasitic-capacitance]

Capacitance that arises from the physical layout of the circuit and the placement of components. Particularly notable when the addition of capacitance is undesirable.

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43 views

Thin Film Resistors, Deposition On One Side, Parasitic Capacitance if Resistor is placed such that Deposition next to PCB Ground Plane

I have a question for all high frequency and RF electrical engineers. Thin film resistors have a vapor deposition of resistive material on one face of the component. Let's presume that the resistor ...
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MOSFET output parasitic capacitance Coss

What is the difference between MOSFET output capacitances that can be seen in the datasheet? (MOSFET energy-related vs time-related vs static output capacitance Coss?) For example in the datasheet, a ...
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464 views

Wouldn't using two MOSFETs in push-pull configuration to drive a single MOSFET be counter-productive?

I'm trying to make a buck converter that uses a P-MOS for high-side switching using an STM32's PWM signal. I can't figure out why it would be useful to drive the MOSFET using a push-pull MOSFET gate ...
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159 views

capacitance at inverting op-amp input of unity gain inverting amplifier

[This question is related to another question. That other question asks why a particular op-amp behaves the way it does. I think there are many reasons, many of which are outlined in the answers to ...
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How would parasitic capacitance changes happen in a crystal oscillator?

This article about crystal oscillators talks about the trade-offs of different crystal load capacitance values (crystal load capacitance parameter, not load capacitor values) It says “a crystal with a ...
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63 views

Why are parasitic capacitances the main factor for limiting high frequency performance of active devices such as transistors? [closed]

According to the Wikipedia article, the reason for the limit of frequencies in which transistors operate is the parasitic capacitance. But I don't understand why this is so. Wikipedia article: ...
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MOSFET diffusion to substrate capacitance

in order to eliminate body effect one way is to connect the substrate to source when the well is for a single device (PMOS with a well in a CMOS for example) , but i read that it increases the source ...
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28 views

Capacitances in a PMOS transistor: what about the n-well?

So I'm studying MOS transistors and came across the topic of capacitances between various terminals/contacts, including the bulk terminal. These capacitances are due to lateral diffusion as a ...
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TPS61090 LBI Pin-->frequency compensating capacitor for voltage divider?

I was reverse-engineering some PCB to gain knowledge how to apply a TPS61090 Boost Converter (see my schematics attached, sorry for the unusual "arrangement" of the components). Input VBAT ...
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1answer
193 views

I2C bus fails after a few sensor reads

I'm building a small home automation hobby project for which I try to connect 4 temperature/humidity sensors (AM2320) to an I2C bus on the Raspberry Pi. When initially connecting the sensors they work ...
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26 views

Modelling an STM Tip current

As part of a current-to-voltage preamplifier that I'm working on improving, I'm trying to model the current source of an scanning tunneling microscope (STM). The way it works is described below (based ...
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Location transformation of parasitics

I have an question for which I could not get an answer, even from google. What is location transformation for parasitic? How do people deal with it? And what is the significance of it in whole vlsi ...
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How to rederive the formulas for parasitic capacitance of a spherical tesla coil topload

I wanted to prove, or rederive, the formulas for parasitic capacitance of both a toroidal topload, and a spherical topload used for a tesla coil. I thought I'd start with the spherical because the ...
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1answer
48 views

Resistor-Capacitor-Resistor configuration and layout differences

How you can explain the R-C-R configuration? Goertz zobel link to the web-article This looks to be used as a RF audio cable terminating, I suppose. Which can be the electro-technical difference of ...
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57 views

Plannar Inductor Unacounted Parasitic Capacitance

I'm trying to determine the source of approximately 300pf worth of parasitic capacitance in a planar coil project I'm working on. I'm trying to find out how my numerical predictions line up with the ...
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70 views

Why does op-amp output impedance / parasitic input capacitance pole cause a noise peak?

I was simulating the above circuit in LTspice... I realize the main problem here is the 2MHz peak (which should be fixable with proper compensation), but I'm curious about the smaller 398kHz peak ...
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Understanding spef format

Please help me to understand below scenario which is there inside the spef file. I have written only the snapshot, not the full text. ...
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72 views

What effect does the internal re-arrangement of charges have on the existing current? [duplicate]

In the figure, the circuit is physically isolated from Earth (The black line at the bottom). The red capacitors are parasitic capacitors. Under switching conditions the node voltages relative to the ...
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154 views

Is this internal rearrangement of charges in a circuit a current and is this current different from the “normal” current of the circuit?

In the figure, the circuit is physically isolated from Earth (The black line at the bottom). The red capacitors are parasitic capacitors. Under switching conditions the node voltages relative to the ...
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1answer
1k views

How much is parasitic capacitance of soldering pads on PCB?

I mounted a Resistor (SMD, Size: 0603, Resistance 500MOhm) on a PCB. What is the value of its parasitic capacitance? How would it change if it were 0402 in size? Does it depend a lot on the ...
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59 views

Speedup capacitor for compensating stray capacitance

I may be wrong here but I think C1 and C2 charge to different polarities, so when the output changes, C2 supplies the required charge(+ or -) to C1 quickly. For example: If the output is \$+V_{...
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What's the best procedure to model a real world transformer which is not so simple

I have a transformer with a 110-1 turns ratio. The output winding (1100 turns) is typically open circuit, with only its parasitic capacitances as a load. The output winding has adjacent turn ...
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131 views

I am trying to understand the behavior of a pulse

I have this pulse This is the observed data. I have a LTSPice model that needs to be matched as close as possible to the observed data I need to match the e area of from 350 to 500 ns, because the ...
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315 views

Input and Output capacitance

I have understood that there are both input and output parasitic capacitances in real op-amps, but I am trying to understand why they are there. As for the input capacitance, there are two types: ...
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Parasitic capacitance of a chip

I know that the parasitic capacitance of a chip is pronounced Cdyn. If I apply on some scenario one the chip which will toggle the all of its transistors with two different voltages, but the frequency ...
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Understanding capacitance in oscilloscope probe tip

I am trying to understand the capacitance and resistance in oscilloscope probe tip. In the above attached image, that 9Mohm resistance is used for that 1x and 10x setting that divides the input ...
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Measurement of Resistor Parasitics Inductance and Capacitance

I have seen people doing some measurements of parasitic capacitance and inductance of some resistors, by using a vector analyzer and analyzing the graph of S11 with respect to frequency. To get this ...
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135 views

Perf board parasitic capacitance fries microcontroller?

Recently one of my mirocontrollers fried in a project on a perf board. Eight of the outputs are PWM, and aside from the power lines, there are no other outputs from the MCU. The PWM frequency is 40 ...
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474 views

MOSFET input and output capacitances

I need some explanations about the MOSFET parasitic capacitances. Precisely, what I studied is that there are those parasitic capacitances: But generally in digital electronics texts I see that they ...
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1k views

Measuring parasitic capacitance of coil using an LCR meter

Would it possible to use an LCR meter (DE 5000) to measure the parasitic capacitance of an multi-tapped torid inductor? If this is possible how should i do this, to get the best results? Help is much ...
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397 views

Doesn't building a circuit "Manhattan-style" introduce lot of parasitic capacitance?

I watch a lot of circuit building videos on Youtube and I can see that the "Manhattan" style of circuit building (placing small islands of copper clad board on a larger piece which acts as the ground ...
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201 views

In what condition power MOSFET gate capacitances Cgs and Cgd can be paralleled?

I would like to get some understanding about the gate charge of a power MOSFET. I am referred to this MOSFET gate drive circuit application note: https://toshiba.semicon-storage.com/info/docget.jsp?...
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146 views

how to isolate coupled noise source in parasitic capacitance in high voltage pcb design?

I'm new designing a high/medium voltage (V <=10kV) with low voltage and low current (10mA). There will be only a few HV relays. Their coils will be triggered by LV. I have read some literature ...
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98 views

Relaxation Oscillator Issue, comparator self-oscillating at 25 MHz (40ns propagation delay)

I have a relaxation oscillator circuit, which is supposed to oscillate around 6 MHz, and mostly it oscillates in a very stable manner around it. However sometimes it starts to oscillate at 25 MHz, ...
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64 views

MOSFET Controled Relay Problem

As a way to power-on/-off a circuit load, a MCU is used to drive a relay through two MOSFETs. The problem is, when the MCU GPIO output is measured 0-volt, the relay could stay connected. Can anybody ...
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369 views

Using only stray capacitance for MCU oscillator circuits

I've included a diagram of typical Pierce oscillator circuit taken from ST Application Note AN2867: The note suggests that C_L1 and C_L2 should be chosen such that the following equation holds: ...
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179 views

Does (stray) capacitance depend on voltage?

While thinking about how to reduce stray capacitance on my pcb, I got triggered by the question: Should the stray capacitance depend on the voltage difference? Acccording to the equation of ...
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Spike in RTL Inverter

I do not understand the cause of this spike which can be observed in an RTL inverter (but also in a CMOS inverter). In the following image it is the peak at 10 mS (I have considered as input a signal ...
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1answer
39 views

Measurement of Cmos Parasitic capacitors

i've had a question which asks if we assume that capacitance of capacitors with w/l of 1u/0.5 are then what are capacitance of capacitors (with the actual w/l) now i know cgs in saturation for ...
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100 views

Measuring current vs voltage

Let's say that I have a periodic charge build-up across the capacitor C1. I could either choose to measure the current using a transimpedance amplifier as shown below or could measure the voltage ...
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84 views

Electrical properties of a stack of strip board connected by through-hole pins/sockets

I'm aware that breadboards have a limit of 1-2MHz. I think this is because of capacitance. Are there similar limits for a stack of stripboard connected by through-board sockets/pins? Would breaking ...
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Do MRI magnets oscillate due to parasitic capacitance?

Moved here from SE Physics. Do MRI magnets oscillate during charging or even during persistant mode due to parasitic capacitance? What problems can this cause? I am planning a low temp ...
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1answer
121 views

Tesla coil, where do the sparks from the secondary coil ground to?

This might be an obvious question, but I was wondering how a Tesla coil emits sparks that's seem to complete a circuit in thin air, and how one end of the secondary completes a circuit with the other ...
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determine the cutoff frequency of a nMOS in common gate with gate resistance

I have to determine the upper cutoff frequency of this circuit. I absolutely mustn't use the laplace domain because it's too time consuming so not compatible with the time I have at the exam. A rapid ...
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117 views

What is the use of CC_to_GND option in starrc extract?

While doing parasitic extraction using starrc tool, I see there is a switch CC_ti_GND. It combines all the coupling caps and gives the cap with GND. So my doubt is, in which case would it be useful ...
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691 views

Approximate Capacitance of a Multilayer Solenoid Coil

I'm interested in an expression for the capacitance or resonant frequency of a Helmholtz like coil (the windings are parallel to the plane of the coil) of circular or square cross section and of the ...
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1answer
484 views

Measuring Vackar Oscillator Output Amplitude and High Frequency Effects

This is somewhat related to my previous question regarding why I wasn't seeing a clamp biasing effect with my JFET Vackar oscillator. I think I figured it out and I'm wondering if you guys agree. ...
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How do the parasitic elements behave in a bidirectional power switch made from back-to-back MOSFETs?

I would like to know how to determine the value of the total internal gate mesh resistor (Rg) and different parasitic capacitors especially Cgs and feedback capacitor Cds of a bidirectional power ...
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Need help modelling the circuit with parasitic capacitance of a power supply in this scenario in SPICE

A single-ended source is connected to an inAmp of a data-acquisition board as follows: As you see above, the shield is shielding the twisted shielded pair cable. The shield is tied only to the earth ...
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Calculating parasitic capacitance of serial zener diodes

simulate this circuit – Schematic created using CircuitLab I have 2 series zener diodes like these in the schematic. Their capacitance is C=225pF How do I calculate their equivalent ...