Investigation of Thermal and Non-Linear Effects on the Performance of the Power Amplifier - BAW Filter - Chain in a LTE Transmitter

Thermal and non-linear effects on the power amplifier - bulk-acoustic wave (BAW) filter chain of a transmitter for LTE band 2 (1850 MHz to 1910 MHz) are investigated. Both components are co-designed and densely packaged using a silicon-ceramics substrate technology. Thermal effects, caused by the DC power dissipation of the power amplifier on the complete TX chain, are examined using finite-element thermal and electrical co-simulation. It is revealed, that the heating of the BAW filter due to the power dissipation of the power amplifier leads to a frequency shift of the filter passband. The influence of non-linear effects, caused by the RF power level, is investigated by a comparison of measurements of the single components and the TX chain. Furthermore, the generation of second-order sub-harmonic and harmonic signals is explored.