Electronics Basics #29 | Enhancement MOSFET: Drain-to-Gate Feedback Bias

Instructor: Dr. Süleyman Burak ÇELİK

How can a MOSFET feed its own drain voltage back to its gate? Follow the original drain-to-gate resistor, determine the enhancement-device coefficient, solve the circuit equation, and reject the root that violates the physical model. Original lesson 44: 12 V supply, RD 2 kΩ, RG 10 MΩ from drain to gate, and grounded source. ID(on) = 6 mA at VGS(on) = 8 V; threshold = 3 V. The full coefficient is k = 0.24 mA/V². Checked result: IDQ ≈ 2.794 mA and VGSQ = VDS ≈ 6.412 V. Both the conduction threshold and saturation condition are checked, along with the voltage loop and original device equation. The graph distinguishes the below-threshold cutoff region from the conducting curve. Ideal DC model with negligible gate leakage, no channel-length modulation and suitable device ratings; not a general resistor-selection rule. Chapters: 0:00 The goal: find the current and the gate voltage 1:05 Build the enhancement-device equation 2:18 The drain feeds back to the gate 3:29 Combine the circuit and the device 4:59 Two mathematical roots, one physical answer 6:56 Check conduction, saturation and the supply 8:16 See the operating point and the feedback