SEMICONDUCTOR INTEGRATED CIRCUITS

Crucial problems in the design of a terahertz tripler

Jin Meng1, 2, , Dehai Zhang1, Changhong Jiang1, Xin Zhao1, Jian Huang1, 2 and Dashuai Yan1, 2

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 Corresponding author: Jin Meng, E-mail: mengjin11@mails.ucas.ac.cn

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Abstract: A frequency-multiplied source at the terahertz band using discrete planar Schottky diodes, which is a critical element in heterodyne instruments, has been studied by some domestic research institutions in recent years. Besides the design method, there are still many crucial problems that must be taken into consideration in the design. This article mainly discuss three aspects based on the measured data of a 225 GHz tripler that we designed. Firstly, the accuracy of the diode model concerns the reliability of the simulation results. According to the Spice parameters and the measured results, the physical size and the DC parameter of the Schottky diode can be corrected until there is a good consistency between the simulated and measured results. Secondly, the heat accumulation happens to the Schottky junction when the high input power is added. A steady-state thermal simulation is done and the results show that the hottest temperature is about 140 ℃ with 250 mW input power, which is safe to the diode. Lastly, some non-ideal factors are brought during the assembly process such as the uncertainty in the conductive adhesive shape and location deviation of the circuit. Furthermore, the effect on the performance of the frequency multiplier is calculated in this work.

Key words: terahertz triplerdiode modelheat dissipationassembly error



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Fig. 1.  Sketch of the 225 GHz frequency tripler. (a) Bottom block with the quartz circuits. (b) Detail of the diode cell.

Fig. 2.  Fully assembled 225 GHz unbalanced tripler with bias circuit.

Fig. 3.  HFSS 3-D geometrical model of the 5VA varactor. The passivation layer is about 0.5 $\mu $m thick and the epilayer is about 0.2 $\mu $m thick. A pair of 5VA diodes are used in the design of the 225 GHz tripler.

Fig. 4.  Simulated results with different values of $R_{\rm s}$. The analysis of conversion loss include 0.3 dB loss in the waveguide and 0.2 dB loss in the microstrip.

Fig. 5.  Steady-state thermal simulation results for a 225 GHz tripler with 250 mW input power. (a) The thermal simulation results for the tripler with microstrip line circuit. (b) The thermal simulation results for the tripler with suspended microstrip line circuit (the quartz circuit is glued on the steps in the channel). The hottest temperature around the anode increases by 20 $^\circ C$.

Fig. 6.  Measured efficiency at different input power (at fixed frequency 224 GHz). The highest measured multiplying efficiencies of two triplers are 7.3% and 5.8%,respectively.

Fig. 7.  Simulated results in consideration of the assembly error. (a) The impact of the conductive adhesive (different thickness) on the performance of the tripler. (b) The impact of the location deviation,including position displacement of diodes and quartz substrate,on the performance of the tripler.

Table 1.   The Spice parameters of 5VA-13 varactor.

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    Received: 21 January 2015 Revised: Online: Published: 01 August 2015

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      Jin Meng, Dehai Zhang, Changhong Jiang, Xin Zhao, Jian Huang, Dashuai Yan. Crucial problems in the design of a terahertz tripler[J]. Journal of Semiconductors, 2015, 36(8): 085003. doi: 10.1088/1674-4926/36/8/085003 J Meng, D H Zhang, C H Jiang, X Zhao, J Huang, D S Yan. Crucial problems in the design of a terahertz tripler[J]. J. Semicond., 2015, 36(8): 085003. doi: 10.1088/1674-4926/36/8/085003.Export: BibTex EndNote
      Citation:
      Jin Meng, Dehai Zhang, Changhong Jiang, Xin Zhao, Jian Huang, Dashuai Yan. Crucial problems in the design of a terahertz tripler[J]. Journal of Semiconductors, 2015, 36(8): 085003. doi: 10.1088/1674-4926/36/8/085003

      J Meng, D H Zhang, C H Jiang, X Zhao, J Huang, D S Yan. Crucial problems in the design of a terahertz tripler[J]. J. Semicond., 2015, 36(8): 085003. doi: 10.1088/1674-4926/36/8/085003.
      Export: BibTex EndNote

      Crucial problems in the design of a terahertz tripler

      doi: 10.1088/1674-4926/36/8/085003
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      • Corresponding author: E-mail: mengjin11@mails.ucas.ac.cn
      • Received Date: 2015-01-21
      • Accepted Date: 2015-02-25
      • Published Date: 2015-01-25

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