K-Band Frequency Synthesizer with Subharmonic Signal Generation and LTCC Frequency Tripler

A subsystem implementation study of a fractional-N frequency synthesizer for K-band satellite communications is presented. The architecture is based on a subharmonic frequency generation implemented with commercially available voltage-controlled oscillator, phase-locked loop chip and a custom designed frequency tripler implemented in low temperature cofired ceramics with vertical integration techniques. As a key component, the frequency multiplier is analyzed in terms of conversion efficiency and suppression of undesired harmonic signals. With the entire subsystem, a reference-stabilized signal in the range of 19...21 GHz with phase noise of -80 dBc/Hz at 10 kHz offset and a 25 kHz channel spacing is achieved. The output power is -1 dBm and the spectral purity better than 25 dBc over the entire range. With the presented approach it is demonstrated that the employed technology can be used to successfully design customized, packaged modules and subsystems in the upper microwave frequency range.