depletion vs enhancement type mosfet

difference-tables

Comparison Between Depletion-Type and Enhancement-Type MOSFETs

Feature / Parameter	Depletion-Type MOSFET (D-MOSFET)	Enhancement-Type MOSFET (E-MOSFET)
Physical Channel (at $V_{GS}=0\text{V}$)	A physical, structurally implanted channel exists between the source and drain regions.	No physical channel exists structurally. The channel must be induced electronically.
Default Switch State	Normally ON: Conducts current ($I_{DSS}$) even when the gate-to-source voltage is zero ($V_{GS}=0\text{V}$).	Normally OFF: Non-conducting when $V_{GS}=0\text{V}$; current cannot flow until a minimum voltage is applied.
Operating Modes	Can operate in both Depletion mode (narrowing the channel) and Enhancement mode (widening the channel).	Operates only in Enhancement mode (creating and widening the channel).
Characteristic Equation	Follows Shockley’s equation: $I_D=I_{DSS}{\left(1-\frac{V_{GS}}{V_P}\right)}^2$	Follows the enhancement non-linear equation: $I_D=k(V_{GS}-V_{GS(\text{Th})}{)}^2$
Control Parameter	Controlled by Pinch-off voltage ($V_P$ or $V_G$).	Controlled by Threshold voltage ($V_{GS(\text{Th})}$).
Gate-Source Voltage ($V_{GS}$) (for n-channel)	Can be negative (depletion mode), zero, or positive (enhancement mode).	Must be strictly positive and greater than $V_{GS(\text{Th})}$ to turn the device on.
Circuit Symbol Representation	Depicted with a solid, continuous line connecting the Drain, Channel, and Source, symbolizing a built-in physical channel.	Depicted with a broken, dashed line between the Drain, Channel, and Source, symbolizing the absence of a built-in channel.
Primary Applications	Constant current sources, high-input impedance linear amplifiers, and zero-bias circuits	Digital logic gates (CMOS), high-speed switching circuits, power electronics, and memory arrays.