A 60 GHz-band coplanar MMIC active filter

This paper presents the design and performance of a 60 GHz-band coplanar active filter. To compensate the loss of a passive filter, a resonator composed of a quarter-wavelength line is terminated by a negative resistance circuit. A cross-coupling is introduced to make attenuation poles at both sides of the pass-band. A fabricated filter with two resonators shows an insertion loss of 3.0 dB with a rejection of greater than 20 dB at 3 GHz-separation from a center frequency of 65.0 GHz. The size of the filter is 2.5 mm /spl times/ 1.1 mm.