Konstruktion och utvärdering av diplexer
The report descripbs how a diplexer for a hybrid analog/digital filterbank has been constructed and tested. A diplexer divides the frequency band into two different bands that do not who doesn't overlapp each other. The sampling rate for the two ADC:s is 80 Msps, and therefore it is advantage to have zero at 80 MHz. The reason for this is that a proposed class of hybrid filterbanks with very good quality requires a zero at or close the sampling frequency to work well. The diplexer was made in three versions. The first didn't work since the choosen inductance self resonance frequency was to low and by the same range as the filters bandwidth. The second version had to much losses, which resulted in attenuation at 80 MHz, which was to small. The third version was made in two differents layout. To the diplexer it was also made a test tool in Labview, through that one gets the magnitude ande phase functions. The results show that the magnitude function is good for version 3.0 and for version 3.1, and that the losses are low. It depends also on that the choosen components have a high self resonance frequency. There can't been shown any differences between these two, thus is is difficult to judge if one is better then an other.