A system-on-package structure LTCC resonator for a low phase noise and power efficient millimeter-wave oscillation

This paper presents effects of a resonator output load line on the performance of an oscillator. To verify the effects, we designed three low temperature co- fired ceramic (LTCC) circular resonators to fabricate three different Ka-band oscillators. The output load line of the resonator connecting a negative resistance generator monolithic microwave integrated circuit ([-]R MMIC) is a conductor backed coplanar waveguide (CBCPW). We propose load lines with a back pad or a lambda/4 short stub to reduce radiation loss at the opposite side of the load lines. The unloaded Q-value of the two proposed resonators is 255 (25% improvement) and 274 (33.4% improvement) respectively, compared to a conventional resonator with a value of 204. While the measured output power and phase noise of an oscillator with a conventional resonator is 5.0dBm and -95.17dBc/Hz at 1MHz offset, the two oscillators using the proposed resonators with a back pad or lambda/4 short stub are measured at 6.34 dBm, -97.33 dBc/Hz, 16.84 dBm, and -101.17 dBc/Hz, respectively, at the same bias condition. We can see that the radiation loss of the output load line exerts a great influence not only on the Q-value of a resonator but also on the output power and phase noise of an oscillator. As the resonators are embedded in the multilayer LTCC block, they are also very suitable for implementing millimeter-wave integrated system applications.