Ka-band harmonic image rejection mixer MMIC design
|School||University of Electronic Science and Technology|
|Course||Electromagnetic Field and Microwave Technology|
|Keywords||Ka-band Harmonic image rejection mixer Double balun structure Lange bridge MMIC|
Monolithic Microwave Integrated Circuit (MMIC) has small size, high stability, small parasitic parameters, consistency and high-volume low-cost, more and more widely used in military and civilian electronic systems. The millimeter-wave mixer is one of the key components of millimeter-wave communications, radar, measuring and electronic countermeasures systems such image rejection mixer can achieve good image rejection in the case of the low-IF, broadband harmonic mixer can make the local oscillation frequency as the fundamental frequency of 1/2 or 1/4, saving the frequency doubler, thereby reducing the cost and technical difficulty of the millimeter-wave systems. According to the theory of harmonic balance, using the French the UMS company's 0.25μm GaAs PHEMT process line, designed based on the FET secondary harmonic image rejection mixer chips using 0.15μm GaAs PHEMT process line designed diode-based fourth harmonic The wave image rejection mixer. In the design of the second harmonic image rejection mixer, double balun structure provided by the local oscillator signal, composed of two mixer unit provides amplitude inverted Lange bridge, forward parallel FET two Lu equal amplitude quadrature RF signal to the mixer, thus inhibiting the odd harmonic mixer component of the two mixer units; match by the grounded capacitance and the ground resistance of the overall circuit, the conversion loss is reduced and chip area ; final simulation results show that, in the local oscillation frequency range of 16-18GHz, and radio frequency range of 35-37GHz, IF fixed loss fo when the frequency is 11-figure of 11.7 dB, image rejection of greater than 26dB. Fourth harmonic image rejection mixer design, the use of splitters mixing unit consisting of two anti-parallel diode two pieces of the same phase of the local oscillator signal with Lange bridge Lu equal amplitude quadrature RF signals for mixing, thereby suppressing the odd harmonic mixer component of the two mixer units; short and the LO side to load 1/4λRo shorted minor by the load in the RF side 1/4λLo inhibit the leakage of the LO signal to the RF port and the LO signal with the RF signal of the second mixer, thereby decreasing the conversion loss; final simulation results show that, in the local oscillation frequency range of 8.25-9GHz, radio frequency range. 34-36GHz, the mid-range for 0-1GHz 12.2-13.7dB conversion loss, image rejection is higher than 28dB, the actual measurement IF as 50MHz, 500MHz and 1GHz conversion loss of 12-16dB image rejection degree greater than 16dB.