Input Impedance of Low Noise Amplifier Calculator

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Low Noise Amplifier

✖Transconductance is a measure of how much current the amplifier can produce for a given input voltage.ⓘ Transconductance [g_m]			+10% -10%
✖Feedback Factor is a critical parameter that determines the stability and noise performance of amplifiers.ⓘ Feedback Factor [α]			+10% -10%
✖Load Impedance is a measure of the resistance that the load presents to current flow at the FET's output.ⓘ Load Impedance [Z_l]			+10% -10%

✖Input Impedance is the opposition to current flow into an electrical circuit when a voltage is applied to its input terminals.ⓘ Input Impedance of Low Noise Amplifier [Z_in]

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Formula

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Input Impedance of Low Noise Amplifier

Formula

`"Z"_{"in"} = (1/"g"_{"m"})+"α"*"Z"_{"l"}`

Example

`"1.069516Ω"=(1/"2.18S")+"0.06"*"10.18Ω"`

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Input Impedance of Low Noise Amplifier Solution

STEP 0: Pre-Calculation Summary

Formula Used

Input Impedance = (1/Transconductance)+Feedback Factor*Load Impedance
Z_in = (1/g_m)+α*Z_l
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

Z_in = (1/g_m)+α*Z_l --> (1/2.18)+0.06*10.18

Evaluating ... ...

Z_in = 1.06951559633028

STEP 3: Convert Result to Output's Unit

1.06951559633028 Ohm --> No Conversion Required

FINAL ANSWER

1.06951559633028 ≈ 1.069516 Ohm <-- Input Impedance

(Calculation completed in 00.004 seconds)

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Created by Suma Madhuri

VIT University (VIT), Chennai

Suma Madhuri has created this Calculator and 50+ more calculators!

Verified by Parminder Singh

Chandigarh University (CU), Punjab

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< 18 RF Microelectronics Calculators

Energy Stored in all Unit Capacitances

Go Energy Stored in All Unit Capacitances = (1/2)*Value of Unit capacitance*(sum(x,1,Number of Inductors,((Value of Node N/Number of Inductors)^2)*((Input Voltage)^2)))

Equivalent Capacitance for n Stacked Spirals

Go Equivalent Capacitance of N Stacked Spirals = 4*((sum(x,1,Number of Stacked Spirals-1,Inter Spiral Capacitance+Substrate Capacitance)))/(3*((Number of Stacked Spirals)^2))

Total Noise Power Introduced by Interferer

Go Total Noise Power of Interferer = int(Broadened Spectrum of Interferer*x,x,Lower End of the Desired Channel,Higher End of the Desired Channel)

Feedback Factor of Low Noise Amplifier

Go Feedback Factor = (Transconductance*Source Impedance-1)/(2*Transconductance*Source Impedance*Voltage Gain)

Return Loss of Low-Noise Amplifier

Go Return Loss = modulus((Input Impedance-Source Impedance)/(Input Impedance+Source Impedance))^2

Total Power Lost in Spiral

Go Total Power Lost in Spiral = sum(x,1,Number of Inductors,((Corresponding RC Branch Current)^2)*Substrate Resistance)

Noise Figure of Low Noise Amplifier

Go Noise Figure = 1+((4*Source Impedance)/Feedback Resistance)+Noise Factor of Transistor

Gate to Source Voltage of Low Noise Amplifier

Go Gate to Source Voltage = ((2*Drain Current)/(Transconductance))+Threshold Voltage

Threshold Voltage of Low Noise Amplifier

Go Threshold Voltage = Gate to Source Voltage-(2*Drain Current)/(Transconductance)

Transconductance of Low Noise Amplifier

Go Transconductance = (2*Drain Current)/(Gate to Source Voltage-Threshold Voltage)

Drain Current of Low Noise Amplifier

Go Drain Current = (Transconductance*(Gate to Source Voltage-Threshold Voltage))/2

Voltage Gain of Low Noise Amplifier given DC Voltage Drop

Go Voltage Gain = 2*DC Voltage Drop/(Gate to Source Voltage-Threshold Voltage)

Load Impedance of Low Noise Amplifier

Go Load Impedance = (Input Impedance-(1/Transconductance))/Feedback Factor

Input Impedance of Low Noise Amplifier

Go Input Impedance = (1/Transconductance)+Feedback Factor*Load Impedance

Output Impedance of Low Noise Amplifier

Go Output Impedance = (1/2)*(Feedback Resistance+Source Impedance)

Source Impedance of Low Noise Amplifier

Go Source Impedance = 2*Output Impedance-Feedback Resistance

Drain Resistance of Low Noise Amplifier

Go Drain Resistance = Voltage Gain/Transconductance

Voltage Gain of Low Noise Amplifier

Go Voltage Gain = Transconductance*Drain Resistance

Input Impedance of Low Noise Amplifier Formula

Input Impedance = (1/Transconductance)+Feedback Factor*Load Impedance
Z_in = (1/g_m)+α*Z_l

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 Z_in 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 (g_m), Feedback Factor (α) & Load Impedance (Z_l) 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 Z_in = (1/g_m)+α*Z_l 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 (g_m), Feedback Factor (α) & Load Impedance (Z_l). 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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