Design Of A Millimeterwave Upconverter

Frequency multipliers, oscillators and mixers are key building blocks of VSAT (Very Small Aperture Terminal) satellite transmitter. The local oscillator and its frequency multiplier are analyzed in this paper, and a subharmonic mixer is introduced in the end.A comprehensive survey of the techniques used in the analysis and design of frequency multipliers is introduced first. An alternative biasing condition for a frequency tripler yields advantages over conventional approaches. The maximum measured conversion gain reaches 2.2 dB for an input power of–1 dBm at the fundamental frequency of 4875 MHz.The fundamental characteristics of dielectric resonators and microstrip hairpin resonators are described. An X-band dielectric resonator oscillator (DRO) and a hairpin oscillator are implemented and tested. Phase noise characteristics of both oscillators are analyzed in detail. Measurement results are given and compared with each other. The DRO shows an ultra low-phase noise performance:–110 dBc/Hz at 10kHz offset and–120 dBc/Hz at 100kHz offset. Its output power reaches 7.8dBm at an operating voltage of +3V. The hairpin oscillator circuit is fabricated with MIC technique, but can be compatible with MMIC due to its fully planar structure. On the other hand, low Q of the microstrip hairpin resonator results in poor phase noise performance of the oscillator.An analytical investigation of antiparallel sub-harmonic mixers (SHM) is presented in the end. It shows that such a configuration reduces the local oscillator frequency, and makes it more promising in millimeterwave systems.