Low Noise Amplifier (LNA) Design — 4.5 GHz | AWR Microwave Office

This repository presents my M.Sc. Microwave Circuits and Systems project,
developing a Low-Noise Amplifier (LNA) at 4.5 GHz using NI AWR Microwave Office.
The project focuses on achieving maximum transducer gain, unconditional stability, and microstrip implementation on Rogers RO4003C.

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🎯 Project Overview

• Objective: Design and implement a stable low-noise amplifier around the BFP620F transistor with maximum transducer gain.
• Technology: Microstrip line design using Rogers RO4003C substrate (32 mil).
• Simulation Tool: NI AWR Microwave Office.
• Measured Frequency: 4.5 GHz.
• Achieved Gain: ≈ 13.3 dB (stable).
• Bias Point: VCE = 2 V, IC = 15 mA.

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⚙️ Design Flow

1. Specification Definition — Bias point, transistor selection (BFP620F), substrate choice.
2. S-Parameter Analysis — Extract S11, S12, S21, S22 at 4.5 GHz.
3. Stability Verification — Ensure unconditioned stability (K > 1).
4. Matching Network Design — Lumped-element networks (input & output).
5. Transmission-Line Replacement — Convert ideal elements to microstrip (MLIN/MLEF).
6. Biasing Network — Design DC biasing for BFP620F (VCE = 2 V, IC = 15 mA).
7. Simulation — Verify gain, return loss, and stability in AWR.
8. Fabrication & Lab Testing — Implement PCB, measure gain and compare results.

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📐 Key Equations

[ Γ_S = \frac{B_1 ± \sqrt{B_1^2 - 4|C_1|^2}}{2C_1}, \quad Γ_L = \frac{B_2 ± \sqrt{B_2^2 - 4|C_2|^2}}{2C_2} ]

[ G_T = G_S + G_0 + G_L, \quad G_T^{max} = 13.77 \text{dB} ]

Gain stages:

• ( G_S = 1/(1 - |Γ_S|^2) )
• ( G_0 = |S_{21}|^2 )
• ( G_L = (1 - |Γ_L|^2)/|1 - S_{22}Γ_L|^2 )

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📊 Design Data

Parameter	Value / Result
Transistor	Infineon BFP620F
Substrate	Rogers RO4003C (εr = 3.55, h = 32 mil)
Frequency	4.5 GHz
Gain (Simulated)	13.33 dB
Stability (μ-test)	μ = 1.035 > 1 → Stable
DC Bias	VCE = 2 V, IC = 15 mA
PCB Housing	0805 passives

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🖼 Gallery

Simulation and Layout

AWR Schematic	Microstrip Layout

Simulation Responses

Response (Initial)	Response (After Tuning)	T-Junction Response

Stability and Noise Analysis

Stability Check

Fabrication and Measurement

Fabricated PCB	Lab Measurement Setup

🧩 Folder Structure