RF Amplifier Gain Calculator

Calculator Inputs

Use direct power values, voltage values, or both for cross-checking.

Frequency (MHz)

Used for reporting and RF context.

Input Power

Input Power Unit

Output Power

Output Power Unit

Number of Cascaded Stages

Applies the corrected stage gain repeatedly.

Input Voltage Vin (Vrms)

Output Voltage Vout (Vrms)

Source Impedance Zs (Ω)

Load Impedance Zl (Ω)

Input Return Loss (dB)

Output Return Loss (dB)

Example Data Table

Frequency (MHz)	Input Power (dBm)	Output Power (dBm)	Input RL (dB)	Output RL (dB)	Stages	Approx. Total Gain (dB)
100	-10	8	18	16	2	35.64
433	-5	12	20	18	2	33.78
900	0	15	22	20	3	44.79

Formula Used

Power Gain:
G_p = P_out / P_in
G_p,dB = 10 × log₁₀(P_out / P_in)

Voltage Gain:
A_v = V_out / V_in
A_v,dB = 20 × log₁₀(V_out / V_in)

Reflection Coefficient from Return Loss:
|Γ| = 10^{-RL / 20}

Mismatch Factor:
M = (1 - |Γ_in|²) × (1 - |Γ_out|²)

Approximate Transducer Gain:
G_T = G_p × M
G_T,dB = 10 × log₁₀(G_T)

Cascaded Total Gain:
G_total,linear = (G_stage)ⁿ
G_total,dB = n × G_stage,dB

This calculator uses a practical mismatch-corrected stage model. It is excellent for early design checks, comparison studies, and quick RF gain budgeting.

How to Use This Calculator

Enter frequency for reference and reporting.
Provide input and output power with correct units.
Add Vin and Vout if you want a voltage-gain check.
Set source and load impedance, usually 50 ohms in RF work.
Enter input and output return loss values to estimate mismatch effects.
Choose the number of cascaded stages for total gain projection.
Press Calculate Gain to show results above the form.
Use the CSV and PDF buttons to save the engineering summary.

FAQs

1) What does RF amplifier gain mean?

RF amplifier gain shows how much an amplifier increases signal power or voltage. It is usually expressed as a linear ratio or in decibels.

2) Why are decibels used for gain?

Decibels make very large or small ratios easier to compare. They also simplify cascade calculations because stage gains add directly in dB.

3) What is the difference between power gain and voltage gain?

Power gain compares output power to input power. Voltage gain compares output voltage to input voltage. They are not always numerically equal, especially when impedances differ.

4) Why does return loss matter in RF gain estimates?

Return loss indicates how well each port is matched. Poor matching causes reflections, reduces delivered power, and lowers practical transducer gain.

5) What is transducer gain?

Transducer gain is the gain after considering mismatch-related delivery effects. It is often more realistic than ideal power gain for system planning.

6) How is cascaded gain calculated?

For identical stages, linear gains multiply while decibel gains add. Two 15 dB stages ideally give 30 dB total gain.

7) Can I use voltage inputs instead of power inputs?

Yes. If voltage and impedance are available, the calculator estimates power from V²/R. This is useful for cross-checks or incomplete measurements.

8) Is this suitable for final production design?

It is strong for budgeting and comparison. Final validation should still include full S-parameter simulation, stability checks, compression data, and measured hardware results.