9.4 Layout

9.4.1 Layout Guidelines

Employ good, high-frequency printed-circuit board (PCB) layout techniques for the OPA620. Generous use of

ground planes, short and direct signal traces, and an excellent choice of bypass capacitor located at the V+ pin

provide clean, stable operation. Large areas of copper provides a means of dissipating heat that is generated in

normal operation.

TI does not recommend using sockets with any high-speed amplifier.

A 10nF ceramic bypass capacitor is the minimum recommended value; adding a 1µF or larger tantalum

capacitor in parallel is beneficial when driving a low-resistance load. Providing adequate bypass capacitance

is essential to achieving low harmonic and inter-modulation distortion.

9.4.1.1 Power Dissipation

Power dissipation depends on power-supply voltage, signal and load conditions. With dc signals, power

dissipation is equal to the product of output current times the voltage across the conducting output transistor,

VS − VO. Power dissipation is minimized by using the lowest possible power-supply voltage necessary to provide

the required output voltage swing.

For resistive loads, the maximum power dissipation occurs at a dc output voltage of one-half the power-supply

voltage. Dissipation with ac signals is less. The Power Amplifier Stress and Power Handling Limitations

application bulletin explains how to calculate or measure power dissipation with unusual signals and loads.

Any tendency to activate the thermal protection circuit indicates excessive power dissipation or an inadequate

heat sink. For reliable operation, limit the maximum junction temperature to the value listed in Section 6.3. To

estimate the margin of safety in a complete design, increase the ambient temperature until the thermal protection

is triggered at 160°C. The thermal protection must trigger more than 35°C greater than the maximum expected

ambient condition of the application.

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OPA620

SLOSEG2 – APRIL 2026

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