Temperature Characteristics Survey for a Doherty Power Amplifier

In order to study the temperature characteristics of doherty power amplifier under alpine condition, a series of tests have been carried out here. The results showed that the performance indicators show a significant downward trend at all frequencies as the rising temperature. In detail, the input return loss (S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf>), small signal gain <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathbf{S}_{21})$</tex> and output return loss (S22) decrease 1.62 dB, 1.63 dB and 2.33 dB, respectively. Meanwhile, Pout, gain and drain efficiency (DE) drop about 2.17 dB and 2.18 dB and 1.64 %, respectively. These results indicate that the performance of doherty power amplifier is significantly affected with temperature variations. Due to the truth that the reduction of the 2-D electron gas mobility <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu$</tex> is the key reason for performance deterioration. Therefore, a temperature compensation measure is proposed, which can offset the performance degradation caused by temperature. This can provide important theoretical guidance for the reliability design of doherty power amplifier.