Questions tagged [jfet]
Junction Field Effect Transistor - A transistor whose channel is modulated by the application of an electric field that is the depletion region of a reversed biased diode that forms the gate electrode. Characteristic features of the device are low noise and low gate capacitance.
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Simplest JFET front end to A/D converter
This is regarding a cheap Pmod I2S2 ADC and DAC (connected to an STM32F407G-DISC1) that uses a Cirrus CS5343 ADC.
Now, as best as I can tell from the CS5343 data sheet, the \$ V_{PP} \$ of the input ...
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Why do some JFETs oscillate and others don't?
Below is a simple JFET Clapp Oscillator, which works quite well. It starts oscillating at around 40us and gets into clean, stable oscillation by 100us:
When I replace the J309 JFET with a more ...
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How can this Clapp JFET oscillate when its gate is tied to ground at the resonance frequency?
How does the circuit below oscillate? It seems to have |gain| < 1 at its oscillation frequency of 2.25 MHz, yet it oscillates there.
My analysis:
The DC path is through L4 only, allowing a bias ...
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How to stabilize this op-amp circuit?
I have a "JFET enhanced" op-amp circuit shown below:
"JFET Enhanced" op-amp circuit
Similar to the circuit used in the TI app note: App Note
The circuit looks stable in SPICE with ...
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One point I don't understand about Rs in ac analysis of jfets
In the circuit in this 1st picture, Rs resistance is bridged with C3 capacitor, so Rs is disabled when analyzing ac.
but in this 2nd picture there is a capacitor bridging the Rs resistor, but we draw ...
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Is there an established way to model this PIR + JFET circuit?
Pictured is a PIR (passive infra-red) sensor hooked up to a JFET.
The diagram is from these design notes, which describes the workings of the PIR sensor as:
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Why doesn't my microphone amplifier work?
I designed a microphone amplifier like in the simulation image below. The images of it in real life are also below. The microphone is a JLI2555. The input voltage used in the simulation is 1mV.
When I ...
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Switching circuit with logic 3.3V control on p-channel JFET
The task is to derive sinewave (of higher frequency) chopped by step-function (also periodic but of lower frequency, i.e. several periods of sine wave are placed in that pulse). So I have a sinewave ...
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JFET Pinch-off voltage or threshold voltage
the operating condition of JFET in saturation is stated below from this website.
Vp stands for pinch-off voltage in the article.
But after reading this post shouldn't Vp change to Vthreshold in Vds ...
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What is the input impedance of a JFET common drain amplifier at high frequency?
I have been trying to learn how JFETs work. The first amplifier that I read about was the CS amplifier:
I found that for a typical common source amplifier configuration at low frequency, the input ...
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Shockley equation of an E-MOSFET with a B instead of a K
I have a question about the following homework exercise.
I have no clue what B means in this equation. I could not find meaning of it in google nor in the books.
Could someone link me a resource or ...
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How to filter noise/ripple for a JFET audio amplifier?
In my first realization of a common source JFET preamplifier, I encountered a rather predictable problem but for which I was unable to find any documentation: the power supply ripple and noise are ...
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Best type of switch for very small and sensitive signals
I have an H-bridge connected to a piezoelectric ceramic transducer which feeds it 40kHz 38V AC. After 3 full oscillations, it is stopped and it starts waiting for an echo, which is probably going to ...
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Parameter Interaction Graph of JFET
I am looking at datasheet of the MMBFJ175 P-Channel JFET (Datasheet). There is one graph were I have a really hard time to understand, what it means and how to interpret it. .
IDSS doesn't have a ...
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Resettable integrator resetting to the negative rail not ground
I've recently built a resettable integrator board which uses a low-drift JFET op-amp and a sample and hold chip. The sample and hold amplifier datasheet showed a resettable integrator configuration ...
