August 23, 2022
June 26, 2022
June 29, 2022
Engineering Physics and Physics Division Technical Session 3
In order to conduct applied research and carry out innovation in Monolithic Microwave Integrated Circuits (MMIC) Design and Fabrication technology, theoretical instructions in MMIC, RF, and Microwave electronics course work must integrate fundamentals in research investigations. The analytical calculations are then to be complemented with adequate graphical tools such as Smith Charts and EDA tools like ADS, HFSS, and Microwave Office. In order to validate the design from its conception to the layout stage, the final mask set has to be prepared for fabrication strategy. In Microwave Solid-State Circuits and their Applications at Monolithic stage, this basically involves the design of Input Matching Networks (IMN), Output Matching Networks (OMN) as well as the Inter-stage Matching Networks (ISMN). MMIC modeling in the design of High Power Amplifier involves scaling transistor sizing so as to improve transistor Gain and minimize losses.
The author proposes an innovative method of inferring Smith Charts obtained in ADS and then validating them with MATLAB codes in an academic setting which includes my MMIC Design and Microwave Courses. It incorporates thorough class room understanding of (1) Transmission Line theory fundamentals, (2) MMIC Design, and (3) Smith Charts, which are of vital importance to create perfectly matched networks in the designs. A case study of designing a High Power Amplifier involving IMN, OMN and ISMN is planned to be presented and validated using MATLAB codes. ADS Simulation results of Insertion and Return losses for all the three matching networks will be presented briefly. This will assist the Engineering educators and RF circuit designers to precisely apply their Engineering education knowledge into practice for becoming innovators predominantly in the Emerging technologies focused on RF-Microwave Engineering.
Exhaustive designs using EDA tools of GaAs based monolithic integrated Power Amplifiers (PA), with Metal Semiconductor Field Effect Transistors (MESFET’s), and GaN based High Electron Mobility Transistors (HEMT’s) play an important role in Microwave amplifier applications for 5G operation. Recently, the performance of these GaN based devices has been improved significantly for RF applications deployable in next generation devices such as Front End modules of mobile communication systems. In order to increase the small signal gain of the amplifiers, a multi stage configuration can be employed. However, complexity of the circuit increases significantly as the number of amplifier stages increase. For example, by employing only two-stages, the design of amplifier is already complex, in that achieving perfect inter-stage matching becomes difficult thereby causing device failure as return losses are small. To resolve this, the design of amplifier first stage is undertaken independently, and then the second stage is cascaded to form a two-stage amplifier along with matching networks, resulting in a practical value of return loss for sustaining device operation in low to mid-5G ranges.
In this paper, matching networks of a two-stage GaN HEMT MMIC PA are designed to fully match characteristic impedances of 50-Ω input as well as 50-Ω output. The typical characteristic impedance of 50-Ω at the center of Smith chart-circle is selected such that any large complex impedance values can be plotted by normalizing it with a standard Smith chart utility. With this design, we aim to achieve a 34 dB small signal gain at frequency of 4.89 GHz for lower 5G Transceiver MMIC chipset design because the maximum power handling capacity of GaAs substrate based structures is 6.25 W (38 dBm). Also, non-linearity has been addressed using the large signal parameters and Harmonic Balance Analysis (HBA) in ADS for multi-tone excitations schemes to verify rationality of designed networks for PA functionality.
Prasad, K., & Syed, A. (2022, August), Incorporation of Matching Networks Fundamentals into State-of-the-Art Technology for Electrical Engineering Designs in General and RF-Microwaves Circuits in Particular using Smith Charts and MATLAB Paper presented at 2022 ASEE Annual Conference & Exposition, Minneapolis, MN. https://peer.asee.org/40383
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