Design Of 330GHz Subharmonic Mixer And Its Local Oscillator Lin

Terahertz sub-harmonic mixer is a crucial function module of Terahertz signal receiving and detection systems,it is widely used in terahertz communications,radar,astronomy,imaging and other fields.In this paper,a 330 GHz sub-harmonic mixer and its local oscillator(LO)chain are developed for the application of super-heterodyne receiver in the 330-GHz frequency band.This paper presents the design process and test results of each functional module.The main work of this paper is as follows:According to the requirements of 330 GHz sub-harmonic mixer for local oscillator,a165-GHz active frequency multiplying chain is designed.The LO chain adopts a topology of×12 active frequency multiplying,including a W-band active ×6 frequency multiplier,a Wband driving amplifier,and 165 GHz passive frequency doubler.Among them,the W-band active ×6 frequency multiplier and driving amplifier are implemented based on commercial MMIC chips,and the 165 GHz passive frequency doubler is designed based on commercial discrete varactor diodes and hybrid integrated technology.The design method,design process,simulation and experimental results of the 165 GHz frequency doubler are introduced in detail,and the experimental results are analyzed and discussed.The measurements show that in the160-172 GHz band,the output power is greater than 7.5 m W,the conversion loss is better than 11.6 d B.The measured performance agrees well with the simulation,and meets the requirements of the 330 GHz sub-harmonic mixer.Based on the realization of the LO chain,a 330 GHz sub-harmonic mixer is designed using a 50 μm thick quartz substrate and an anti-parallel Schottky diode.The simulation of diode,LO and RF probe transitions,filtering structure,and the optimization method of the entire circuit are introduced in detail.Based on the optimization results,a prototype is fabricated,assembled and tested.The test results show that the RF bandwidth of the mixer is328-340 GHz,and the IF bandwidth is DC-16 GHz.The conversion loss is 8.9-11.2 d B with 5d Bm LO power.The error analysis and discussion of the factors that may lead to performance deviation are given in the final part.