BROADBAND AMPLIFIER DESIGN FOR OPERATION IN Ku BAND
RAVITHARAN R. (E/02/229)
RAMESH SELVARAJ (E/02/245)
We wish to acknowledge our project supervisor Dr.A.U.A.W.Gunawardena who gave enormous help to success this project. At the mean time we would like to thank Dr.Chandima Ekanayake – Coordinator, Final year undergraduate project.
System Level Design
Circuit Simulation and Design Verification
CHAPTER 01: INTRODUCTION
Build a solid understanding above design methodology and learning CAD tools which are recognized under the industry standard. Fabricating the Broadband Amplifier design and get the measurements, by using network analyzer to check the desired outcomes in Ku band.
According to the course unit system we have to do two undergraduate projects in the 7th & 8th semesters. We have selected the project ‘Broadband Amplifier Design for operation in Ku band’ for both semesters. As the objective, our main task is design, fabricating, and test the Broadband Amplifier. The signals, which are in the range of 10.75GHz to 13.75GHz, are known as Ku band microwave signals. The Broadband Amplifier is an important design component over wide range of frequencies in a microwave receiver.
The Broadband Amplifier design is to be done with Micro strip RF circuit design techniques and the required specifications are derived from the System level design. Therefore the system level design has to be done first. The Satellite Low Noise Block (LNB) is selected for system level design, which is one of the suitable applications for Broadband Amplifier. Receiving signal frequency is in the range of 12.25 GHz to 12.75 GHz for the LNB. Where the broadband Amplifier is used to amplify the receiving signal power after frequency conversion (by using mixer with 11.3 GHz local oscillator) occur.
CHAPTER 02: Literature review
At the first stage the literature review for the project covers the theory behind the communication system and the design methodology and techniques for an efficient microwave design, and system level design and analysis. Initially we have gone through reading materials, which are relevant to wireless communication system. Have a look on super heterodyne principle, noise figure, 1 dB compression point, third order intercept point and spurious free dynamic range related to that.
❖ Superheterodyne principle
Most of the receivers operate on a more sophisticated superheterodyne principle. The following tasks can be achieved by using superheterodyne receivers.
➢ Carrier-frequency tuning to select the desired signal from the air interface. ➢ Filtering to separate the desired signal from other received signal with that. ➢ Amplification to compensate for transmission loss.
➢ Image Rejection.
➢ High-side and Low-side injection.
Fig. No. 01: Superheterodyne receiver
The incoming signal is selected first, and amplified by a RF section tuned to the desired carrier frequency fc. The amplifier has a relatively broad bandwidth BRF that partially passes adjacent channel signals along with incoming signal. Next a frequency converter comprised of a mixer, and local oscillator translates the RF output down to an IF frequency at fIF < fc. The adjustable LO frequency tracks with the RF frequency tuning such that
fLO= fc + fIF or fLO= fc-fIF
❖ Noise Figure: The noise figure indicates how much the receiver degrades the input signal’s signal to noise ratio. NF = (S/N) input / (S/N) output
Where S: Signal power, N: Noise power
References: 1. A.Bruce Carlson, Paul B.Crilly, and Janet C. Rutledge,”Communication System”, 1937.
3. Guillermo Gonzalez, “Microwave Transistor Amplifiers Analysis and Design”, 1997
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