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RF3928B

DS120503

7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical

support, contact RFMD at (+1) 336-678-5570 or customerservice@rfmd.com.

Device Handling/Environmental Conditions

GaN HEMT devices are ESD sensitive materials. Please use proper ESD precautions when handling devices or

evaluation boards.

GaN HEMT Capacitances

The physical structure of the GaN HEMT results in three terminal capacitors similar to other FET technologies.

These capacitances exist across all three terminals of the device. The physical manufactured characteristics of

capacitances change value as the terminal voltages are varied. RFMD presents the three terminal capacitances

cess, the parasitic capacitances of the package that holds the amplifier is removed through a calibration step.

Any internal matching is included in the terminal capacitance measurements. The capacitance values presented

DC Bias

the device is saturated and uncontrolled drain current will destroy the transistor. The gate voltage must be taken

to a potential lower than the source voltage to pinch off the device prior to applying the drain voltage, taking care

RF Power transistor performance capabilities are determined by the applied quiescent drain current. This drain

current can be adjusted to trade off power, linearity, and efficiency characteristics of the device. The recom-

operational characteristics for this device, considering manufacturing variations and expected performance.

The user may choose alternate conditions for biasing this device based on performance trade off.

Mounting and Thermal Considerations

teristics. This is measured using IR microscopy capturing the device under test temperature at the hottest spot of

the die. At the same time, the package temperature is measured using a thermocouple touching the backside of

the die embedded in the device heatsink but sized to prevent the measurement system from impacting the

results. Knowing the dissipated power at the time of the measurement, the thermal resistance is calculated.

In order to achieve the advertised MTTF, proper heat removal must be considered to maintain the junction at or

below the maximum of 200°C. Proper thermal design includes consideration of ambient temperature and the

thermal resistance from ambient to the back of the package including heatsinking systems and air flow mecha-

nisms. Incorporating the dissipated DC power, it is possible to calculate the junction temperature of the device.