Design of Mixers for Microwave and Millimeter-wave Applications
Date Issued
2010
Date
2010
Author(s)
Lin, Shih-Kai
Abstract
This thesis discusses an gate-pumped resistive sub-harmonic mixer, high frequency broadband diode mixer with improved balun in high frequency and a single-ended gate-pumped sub-harmonic mixer. The main purpose is to reduce the level of LO power needed to drive a mixer.
This thesis consists of three parts and they are all passive mixer in common. The first part introduced a 71-76 GHz balanced resistive gate-pumped mixer using in pHEMT process. Based on this topology, a 60 GHz demodulator is also presented. In the second part, a high frequency diode mixer for space observation is realized. Because the MOSFET fabricated by Si-based material has no gain in such high frequency, the circuits in high frequency usually are implemented in GaAs process. However the thickness of the substrate in these processes is large and may corrupt the ideal ground needed in Marchand balun. A modified Marchand balun which has better coupling factor and resists non-ideal ground effect is introduced in this part to enhance the symmetry of the circuit and relieve the design difficulty. A single-ended gate-pumped sub-harmonic mixer is designed and presented in part three. Without the baluns, the size of the mixer can be more compact than balanced mixers. Although there is no balun, the isolation can still be achieved by filter using coupled-line resonator which is more compact than a balun. Connecting drain to body can help the problem that dc voltage of drain changes. Due to its simple topology, this mixer can be driven with LO power of about only 0 dBm, and eases the requirement of other components in the system.
Subjects
Gate-pumped sub-harmonic mixer
Marchand balun
demodulator
coupled-line resonator
feedback from drain to body
Type
thesis
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