Transmitter filter with integral directional coupler for cellular telephones

摘要

A cellular telephone transmitter (100) includes a variable-gain power amplifier (102), the output of which is filtered and sampled by a filter (104) with an integral directional coupler. Filter (104) includes both a transmitter signal filter and a directional coupler on a ceramic block of one or more pieces. The directional coupler has been realized by two coupled transmission lines provided by the two holes (206 and 207) on the left side of the ceramic block, and the transmitter filter has been realized by five short-circuited coupled transmission lines provided by the five holes (201-205) on the right side of the ceramic block.