depletion mode

[də′plē·shən ‚mōd]

(electronics)

Operation of a field-effect transistor in which current flows when the gate-source voltage is zero, and is increased or decreased by altering the gate-source voltage.

depletion mode

A transistor that is normally closed (on), allowing current to pass, but is triggered to open (off) and impede current. Contrast with "enhancement mode," wherein the transistor is normally open (off), but is triggered to close (on).

Depletion Mode Is "On"

Depletion mode transistors are always passing current until they are turned off. Enhancement mode devices normally impeded current until they are triggered to turn close and turn on. (Image courtesy of Clive "Max" Maxfield, www.clivemaxfield.com)

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References in periodicals archive

The devices in question were enhancement mode FETs, whereas the test being employed was for depletion mode FETs; specifically, they tested the protection diode across the drain to the source in the FET.

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As world oil goes into depletion mode very visibly after 2008 at about 6 percent per year, the world must improve use efficiency each year by 3 percent, increase the amount of long term renewable, wind and solar, energy produced, and take three percent from current uses to provide the power to accomplish the first and second three.

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LNA assemblies based upon discrete depletion mode devices require both a positive and a negative voltage supply, further complicating the PCB layout and the stabilization of the small and large signal performance over temperature.

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At 900 MHz a depletion mode (D-mode) PHEMT features output power density of 630 mW/mm with power-added efficiency (PAE) of 85 percent at 7 V, while an enhancement mode (E-mode) PHEMT features a PAE of 70 percent and higher from 2 to 7 V and high output power densities, especially at lower voltages.

ENHANCEMENT/DEPLETION MODE INGAP/ALGAAS PHEMT FOR HIGH EFFICIENCY POWER AMPLIFIERS

Since the GaAs depletion mode MESFET requires a negative gate-to-source voltage that controls its state, a driver compatible with the CMOS/TTL components integrated with the RF portion of the switch needed to be developed.

A GaAs driver/decoder utilizing a depletion mode FET process for use in SP4T switch

Depletion mode MESFETs used for the SP4T RF switching elements were optimized for minimal insertion loss and maximum bandwidth vs.

Miniature dual control SP4T switches for low cost multiplexing

To maintain high efficiency, both ICs employ depletion mode MESFETs, which require a low current negative supply for gate biasing.

A 1.9 GHz chipset for PCS applications

It produces one enhancement mode MESFET (EFET, Vt = +0.15 V) and two depletion mode MESFETs (DFET, Vp = -0.6 V) (MFET, Vp = -2).

A flexible and cost effective 2.4 GHz ISM transceiver chip set