Broadband, highly integrated receiver frontend up to 67 GHz

In this paper a novel concept for the realization of a highly integrated receiver frontend is presented. The frontend consists of a forward coupler to split the low frequency path (0-43 GHz) and the high frequency path (43-67 GHz), a mixer for the down conversion of the high frequency input signal and a magnetically tunable filter to achieve a high supression (>;60 dBc) of the image frequency and all other higher order intermodulation products emerging in a non ideal mixer. The combination of the mixer and the tunable filter, both realized in finline technology, and a forward coupler based on microstrip lines allows for assembling a receiver frontend without any substrate interconnects in the high frequency path. This makes it possible to circumvent reflection losses caused by such interconnects thus achieving a conversion loss of the complete frontend of less than 17.9 dB in the frequency range from 43 to 67 GHz. By taking advantage of the cutoff-frequency of the used finline circuits a suppression of more than 60 dBc of the image frequency and all the other spurious mixer responses can be guaranteed.