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# Bias Fet

95 Threads found on edaboard.com: Bias Fet

## Deep N well layout issues

If "lvt" is just PWell without the main VTN implant, then follow the regular fet rules for PWell inside DNW. You should contact the DNW and bias it appropriately (VDD or some other stiff potential that keeps it reverse biased to Psub / Pwell). Where to return DNW depends on what you want from it. Low noise might argue against a (...)

## [Moved]: noise in high Vth and low Vth FET

Yes, you are right, they should be compared with the same Vov voltage. I just use the same Vgs to bias the high Vth and low Vth transistor, and then observe the thermal noise in the current mirror configuration from them. The thermal noise equation is: in^2=KT*(gm)/3. For the low Vth device has higher Vov, with the same Vgs bias condition, which

## Please suggest BJTsor FET for 5GHz oscillator (negative feedback).

I used BFP420 at 5GHz in Negative Resistance configuration, which works better than feedback configurations (at least in this case). Have to spend some time choosing the right bias point and tuning the resonator for the right frequency range.

## Maximum feedback resistor value for biasing an amplifier input

Hello I have a question about a feedback resistor value. To bias an input of an amplifier, we can use a feedback resistor from output to input. Normally we use a high resistance, but there may be problems. 1) Amplifier input impedance If the feedback impedance is higher than the input impedance of the amplifier, input currents may flow

## Basic Concepts about BJT,FET and MOSFET

A BJT has a fairly low input resistance that needs a bias current. A Jfet and a Mosfet have very high input resistance that need a bias voltage. BJTs are small and large and can operate at low or high currents. Most Jfets are small and operate at low currents. Many Mosfets are large and can (...)

## Overvoltage protection one chip solution?

yes, indeed, or indeed the TLV431 which has a lower ref voltage and less bias current draw. However, the bias current can be a problem as if the cct isn't done right then youll end up with the pfet on when you don't want it on,

## JFET common source amplifier

voltage divider Jfet common source amplifier with output voltage biased at the half of supply voltage. what does the above sentence mean???

## Finding the Bias for an FET using ADS (Advanced Design System)

Hello torbai, Thank you. That helps! I am designing a Power Amplifier. Have lost touch with ADS so trying to figure out things. Also, I used the optimized bias points. I simulated the Sparamteres. The S11 looks horrible. So, i want to proceed with the Small signal matching. How do i find the impedance of the transistor? I wi

## 0-50V 0-10A Variable SMPS

Not enough drive current for Q8 to fan. Use a 1V Nch "logic level" fet <<100mOhm. and consider Thermistor on hot spot to regulate bias a fan speed with injected triangle wave to get PWM. V CE(sat) Collector-Emitter Saturation Voltage (I C =500mAdc, I B =50mAdc) Vce(sat) = 0.75Vmax Note : Ic/Ib=10 is common switch configuration, unless special

## Biasing of balanced FET amplifier. Does Rdrain_balanced = Rdrain_single / 2 ?

In most applications of high power balanced amplifiers using 2 fetS (or MOSfets) the gates are biased from separate resistors (through RF chokes or high impedance lines). So the idle current could be adjusted separate for each transistor. Your situation is relative low power, so should be no difference using the same resistor to (...)

## buffer amplifier low voltage to higher voltage

hi, You could use a higher supply voltage to the amp, select suitable MOSfet's from the 'F2' lib in LTSpice. Adjust the bias to suit. Post your asc file. E

## how to use lower vdd devices at higher values

A device's "rating" has many facets, if you drill down into the details. The foundry will call it out at its lowest limiting aspect. It's quite likely that a fet has a higher Vgs and Vgd than its long term reliable Vds at worst case HCI bias. So sometimes (in some topologies) you can safely use a device beyond its simple scare-the-innocent rat

## AWR Load Pull Problem, cant get the required power

Dear All I have a slight problem in my design, I am trying to design a 25W PA from 10MHz to 512MHz and did some AWR simulation, Steps are given below 1- IV Curve to bias point 2- Stabilize fet 3- Find input impedance and its conjugate 4- Do Load Pull measurement using AWRDE Load-Pull wizard now after doing all that I got input impedance

## Vt of an Nmos with Temperature Sweep

1) You might just connect a fet as a MOS diode and bias it with 1uA/square and pick off the voltage, if you can't find a .probe syntax that gives you the operating point value. The model parameter value won't change. 2) mobility drops meanwhile, so you have a foot-race sort of situation. Extrinsic resistances also rise. That's why we use simulat

## Why the voltage @ gate is +11V

It seems clear to me you have a depletion mode fet with and IDSS of 30mA at near zero bias voltage on Vgs. What's the problem?

## FET or Transistor switches not draining

I'm not sure what you mean by 'drained to near ground'. If you mean 'completely non-conducting', if there is no active driving voltage/current to force removal of bias, it is usually done with a resistor across the base/emitter or gate/source to leak away residual charge that might be enough to partially turn the device on. It is very difficult

## How to find the value of Load at the output?

Voltage drop depends on source voltage, dynamic resistance of fet from bias and load R. YOu define what transfer function you want first.

## High side FET driver supply won't work due to rapidly changing voltage?

Hello, I wish to do a two transistor forward converter and drive the upper fet from a fet driver feeding off a bias supply. The bias supply obviously has to be referenced to the source of the upper fet, which is a rapidly changing square wave voltage (in this case a square wave from 0 to 28v AT 200khz). I (...)

## comparative op amp circuit using RSSI of 2 RF recievers ( beginer !!! )

It's very unlikely that the fet circuit does what you want. At least transistor DC bias and R and C values seems to be far off.

## PA enable control in wireless power amplifier

You should do these things properly and respectively to turn off the PA while the Load is still connected. -Switch off the input signal -Turn off the main bias -Turn off the gate/base bias