## Input Impedance of Low Noise Amplifier Solution

STEP 0: Pre-Calculation Summary
Formula Used
Input Impedance = (1/Transconductance)+Feedback Factor*Load Impedance
Zin = (1/gm)+α*Zl
This formula uses 4 Variables
Variables Used
Input Impedance - (Measured in Ohm) - Input Impedance is the opposition to current flow into an electrical circuit when a voltage is applied to its input terminals.
Transconductance - (Measured in Siemens) - Transconductance is a measure of how much current the amplifier can produce for a given input voltage.
Feedback Factor - Feedback Factor is a critical parameter that determines the stability and noise performance of amplifiers.
Load Impedance - (Measured in Ohm) - Load Impedance is a measure of the resistance that the load presents to current flow at the FET's output.
STEP 1: Convert Input(s) to Base Unit
Transconductance: 2.18 Siemens --> 2.18 Siemens No Conversion Required
Feedback Factor: 0.06 --> No Conversion Required
Load Impedance: 10.18 Ohm --> 10.18 Ohm No Conversion Required
STEP 2: Evaluate Formula
Substituting Input Values in Formula
Zin = (1/gm)+α*Zl --> (1/2.18)+0.06*10.18
Evaluating ... ...
Zin = 1.06951559633028
STEP 3: Convert Result to Output's Unit
1.06951559633028 Ohm --> No Conversion Required
1.06951559633028 1.069516 Ohm <-- Input Impedance
(Calculation completed in 00.004 seconds)
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## < 14 Low-Noise Amplifiers and Mixers Calculators

Feedback Factor of Low Noise Amplifier
Feedback Factor = (Transconductance*Source Impedance-1)/(2*Transconductance*Source Impedance*Voltage Gain)
Return Loss of Low-Noise Amplifier
Return Loss = modulus((Input Impedance-Source Impedance)/(Input Impedance+Source Impedance))^2
Noise Figure of Low Noise Amplifier
Noise Figure = 1+((4*Source Impedance)/Feedback Resistance)+Noise Factor of Transistor
Gate to Source Voltage of Low Noise Amplifier
Gate to Source Voltage = ((2*Drain Current)/(Transconductance))+Threshold Voltage
Threshold Voltage of Low Noise Amplifier
Threshold Voltage = Gate to Source Voltage-(2*Drain Current)/(Transconductance)
Transconductance of Low Noise Amplifier
Transconductance = (2*Drain Current)/(Gate to Source Voltage-Threshold Voltage)
Drain Current of Low Noise Amplifier
Drain Current = (Transconductance*(Gate to Source Voltage-Threshold Voltage))/2
Voltage Gain of Low Noise Amplifier given DC Voltage Drop
Voltage Gain = 2*DC Voltage Drop/(Gate to Source Voltage-Threshold Voltage)
Load Impedance of Low Noise Amplifier
Load Impedance = (Input Impedance-(1/Transconductance))/Feedback Factor
Input Impedance of Low Noise Amplifier
Input Impedance = (1/Transconductance)+Feedback Factor*Load Impedance
Output Impedance of Low Noise Amplifier
Output Impedance = (1/2)*(Feedback Resistance+Source Impedance)
Source Impedance of Low Noise Amplifier
Source Impedance = 2*Output Impedance-Feedback Resistance
Drain Resistance of Low Noise Amplifier
Drain Resistance = Voltage Gain/Transconductance
Voltage Gain of Low Noise Amplifier
Voltage Gain = Transconductance*Drain Resistance

## Input Impedance of Low Noise Amplifier Formula

Input Impedance = (1/Transconductance)+Feedback Factor*Load Impedance
Zin = (1/gm)+α*Zl

## Why is input impedance important for LNAs?

Input impedance is important for LNAs for several reasons:

It affects the signal-to-noise ratio. A low input impedance can reduce the SNR of the amplifier by loading down the source.
It affects the bandwidth of the amplifier. A high input impedance can cause reflections of signals, which can distort the signal and reduce the amplifier's bandwidth.
It affects the stability of the amplifier. A high input impedance can make the amplifier more susceptible to oscillation.

## How to Calculate Input Impedance of Low Noise Amplifier?

Input Impedance of Low Noise Amplifier calculator uses Input Impedance = (1/Transconductance)+Feedback Factor*Load Impedance to calculate the Input Impedance, The Input Impedance of Low Noise Amplifier formula is defined as a measure of how much the FET's channel width changes in response to changes in the gate-to-source voltage. Input Impedance is denoted by Zin symbol.

How to calculate Input Impedance of Low Noise Amplifier using this online calculator? To use this online calculator for Input Impedance of Low Noise Amplifier, enter Transconductance (gm), Feedback Factor (α) & Load Impedance (Zl) and hit the calculate button. Here is how the Input Impedance of Low Noise Amplifier calculation can be explained with given input values -> 1.076716 = (1/2.18)+0.06*10.18.

### FAQ

What is Input Impedance of Low Noise Amplifier?
The Input Impedance of Low Noise Amplifier formula is defined as a measure of how much the FET's channel width changes in response to changes in the gate-to-source voltage and is represented as Zin = (1/gm)+α*Zl or Input Impedance = (1/Transconductance)+Feedback Factor*Load Impedance. Transconductance is a measure of how much current the amplifier can produce for a given input voltage, Feedback Factor is a critical parameter that determines the stability and noise performance of amplifiers & Load Impedance is a measure of the resistance that the load presents to current flow at the FET's output.
How to calculate Input Impedance of Low Noise Amplifier?
The Input Impedance of Low Noise Amplifier formula is defined as a measure of how much the FET's channel width changes in response to changes in the gate-to-source voltage is calculated using Input Impedance = (1/Transconductance)+Feedback Factor*Load Impedance. To calculate Input Impedance of Low Noise Amplifier, you need Transconductance (gm), Feedback Factor (α) & Load Impedance (Zl). With our tool, you need to enter the respective value for Transconductance, Feedback Factor & Load Impedance and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.
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