Saw device with improved thermal management

Abstract

This invention focuses on minimizing the hot spots on a filter chip by creating thermal radiators using the mechano-acoustic structures and connection circuitry. A gradual increase of metal to wafer relation is made to provide better heat dissipation and heat sinking. Preferably the shunt lines of the ladder type arrangement of SAW resonators (RS1, RS2, RS3) comprise a broadened section (BBCN). Each two series resonators (RS1, RS2, RS3) that are subsequent to each other in the series signal line are connected via a common busbar (BBCN) extending over a whole length of that subsequent series resonators, a lateral extension of the common busbars represents a first section of a respective shunt line each, each first shunt line section between a node and the parallel resonator (RP1, RP2) of a shunt line (SLS1) comprises a broadened section (BS) that is broader than the common busbar, the broadened section extends over the whole width of the parallel resonator (RP1), the first reflector (REF1) of the parallel resonator that faces the laterally adjacent series resonator is formed from the broadened section (BS).

Description

Background technique [0001] HPUE applications (HPUE = High Power User Equipment, a special class of user equipment for LTE cellular networks) and upcoming 5G implementations place high demands on RF components in terms of high power handling and reliability. Allows HPUEs to transmit at up to 31dBm output power. [0002] Acoustic filters for this type of mobile communication use ladder-type structured SAW resonators that can handle higher power signals. The corresponding acoustic filter chips have to handle more than 1W of power, and as a further obstacle, smaller chip sizes are currently required. High power level filters require thermal management that enables the acoustic chip to avoid premature power compression at too high power levels. [0003] The ideal relationship between input Pin and output power Pout should be linear when power is affected at the input of the filter / duplexer / multiplexer and viewed at the output power. This means the behavior should be as follows:...

AI Technical Summary

Problems solved by technology

However, this linear relationship breaks down when too much power is injected and the output power begins to saturate

This power saturation results in very high local temperature gradients that must be managed to prevent device failure

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