X-band MESFET MMIC Power Amplifier

다국어 초록 (Multilingual Abstract)

The X-band MMIC power amplifier for VSAT was designed with GaAs metal-semiconductor field effect transistor(MESFETs). The 8-finger 800μm and 16-finger 1600μm depletion-mode GaAs MESFETs fabricated by LG Corporate Institute of Technology were used to design the basic power amplifier for VSAT(Very Small Aperture Terminal) application. Marteka Model is employed for the simulation. The circuit will be fabricated on the GaAs substrate which has 11.9 of dielectric permittivity, 100μm of height, and 10μm of metal thickness. When 15dBm of the input power is applied 27dBm is measured.
The GaAs MESFET was biased with A-class operation. This amplifier was for in-wafer probing and consisted of lumped elements such as microstrip spiral inductor, MIM capacitor and NiCr resistor for matching circuits. 27dBm of output power isn’t operated with 15dBm of input power. The reason can inform former fact. 14dB linear gain and –10.5dB, -11dB input and output return loss are obtained and the limited is chip size 2×3mm², After designing, the DRC of the circuit was verified check by Mentor IC Station and HP EEsof Libra 6.1 CAD Tool in order to realize the non-error circuit. In this thesis, the 7.75~8.25GHz MMIC power amplifier was designed with domestic library and the devices which fabrication process were provided by LG CIT.

국문 초록 (Abstract)

본 논문은 VSAT(Very Small Aperture Terminal)용 갈륨 비소 전계효과 트랜지스터를 이용한 MMIC 전력 증폭기에 관한 연구이다. LG 종합기술원에서 설계 및 제작된 갈륨 비소 전계효과 트랜지스터를 사용하여 RF On-wafer 측정용으로 설계되었다. 여러 가지 접지는 Via Hole로 열 방출을 용이하게 하였다. 본 전력 증폭기는 LG 종합기술원에서 제공한 Lumped 소자를 이용하여 입·출력 정합회로를 구현하였으며 마지막 2단의 출력 단 정합은 큰 전력을 견디기 위해 Stub를 사용하였다. 첫 단에는 8-finger 800μm, 그리고 두 번째 단에는 이것을 병렬로 연결한 16-finger 1600μm MESFET를 이용한 2-stage의 0.1W급 전력 증폭기이며, 중심 주파수는 8GHz, 대역폭은 600MHz이다. 전체 MMIC 전력 증폭기의 가로대 세로의 크기는 2×3mm²이다. 0dBm의 입력 전력 인가 시 20dBm의 출력전력과 15dB의 선형 이득과 –10.54dB, -11.4dB의 입출력 반사손실을 갖는 전력 증폭기를 설계 및 제작하였다.

목차 (Table of Contents)

• 1. Introduction 1
• 2. Amplifier Design Theory 4
• 2.1 Power Gain Equations 4
• 2.2 Amplifier Stability 4
• 2.3 Stability Circles 5
• 2.4 Amplifier Design under Conditional Stability Conditions 9
• 2.4.1 Parallel Feedback 10
• 2.4.2 Series Feedback 11
• 2.5 Passive Components for Matching Network 11
• 2.5.1 MMIC Capacitors 12
• 2.5.2 MMIC Inductors 14
• 3. Design of Power Amplifier 17
• 3.1 The character of LG GaAs MESFET 17
• 3.2 Design of Passive Devices 27
• 3.2.1 MMIC Inductors 27
• 3.2.2 MMIC Capacitors 28
• 3.2.3 MMIC Resistors 29
• 3.3 Layout Rule 30
• 3.4 Characteristics of Designed Power Amplifier 31
• 4. Implementation and Measurement 41
• 5. Analysis of MESFET power amplifier 41
• 6. Conclusion 41
• References 42