What Is the Class-E RF Power Amplifier Calculator (Sokal Method)?
Class-E RF power amplifiers achieve theoretical 100% DC-to-RF power conversion efficiency by combining switching-mode transistor operation with a tuned resonant load network.
By enforcing both Zero-Voltage Switching (ZVS) and Zero-Derivative Switching (ZDS / dv/dt = 0) at turn-on, switching dissipation is eliminated.
This calculator utilizes Nathan O. Sokal’s classical analytical design equations to compute optimum load resistance, shunt capacitor, resonant tank inductance, and peak switch stresses.
How Does the Class-E RF Power Amplifier Calculator (Sokal Method) Work?
The calculation evaluates user-provided measurements using recognized domain equations, converts between measurement units, and adjusts for real-world efficiency factors.
Class-E RF Power Amplifier Calculator (Sokal Method) Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
RL is optimum fundamental load resistance, Cshunt provides ZVS shaping, and Vsw,pk represents maximum drain voltage stress on the transistor switch.
How to Use the Class-E RF Power Amplifier Calculator (Sokal Method)
- Enter your primary measurements in the input fields above.
- Select your preferred units (e.g. metric or imperial) if applicable.
- Review or adjust operational assumptions such as field efficiency.
- Click Calculate to instantly generate the full results breakdown and visual chart.
- Use the Reset button at any time to clear the form and test a new scenario.
Step-by-Step Example Calculation
13.56 MHz ISM Band 50W Generator
Input Values:
Understanding Your Result
Your calculated result represents the realistic operational capacity or baseline output under the specified conditions. Comparing theoretical and effective outputs reveals the direct impact of turns, overlap, and practical downtime.
Factors That Affect the Result
Field terrain, operator experience, equipment maintenance, overlap margin, and weather conditions can significantly influence real-world output.
When Should You Use This Calculator?
Use this calculator whenever you need quick, verified estimates for job planning, budgeting, equipment sizing, or project timelines.
Assumptions & Limitations
- Follows Nathan O. Sokal (1975, 2001) analytical Class-E design equations for 50% duty cycle.
- Shunt capacitance C_shunt includes the MOSFET internal output capacitance Coss.
- Transistor breakdown rating must comfortably exceed peak switch drain voltage Vpk ≈ 3.56 Vcc.
Frequently Asked Questions
Calculation Accuracy & Reference Note
This calculator implements verified, deterministic mathematical equations based on published standards. Results should be treated as professional engineering estimates; always verify critical operations with local equipment manuals and site inspections.