Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Transconductance at zero gate bias (S)

Required number input.

Gate-source voltage (V)

Required number input.

Negative pinch-off voltage (V)

Required number input.

Estimate n-channel JFET transconductance with Shockley's square-law model for gate bias between negative pinch-off and zero. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Biased transconductance (S)

The resulting biased transconductance returned as a number.

• JFET transconductance and bias relations use a device model whose parameters vary substantially between parts and with operating point and temperature. Verify bias range, output resistance, noise, capacitance, and the actual transfer curve.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

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