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From: | Jeffrey Lambert |
Subject: | Re: [Discuss-gnuradio] Analog Devices RF RX/TX subsystems for Spartan-3AN FPGA |
Date: | Fri, 18 Jun 2010 00:26:10 -0400 |
User-agent: | Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.9) Gecko/20100317 Thunderbird/3.0.4 |
Hello,An RF Front-end can take many forms, depending upon the application. For use with the USRP or similar hardware, a direct-conversion approach is probably adequate. This type of front-end typically consists of low noise amplifier (LNA), mixer, and perhaps a baseband/IF amplifier or automatic-gain control (AGC) amplifier. Determing the requirements for amplifier gains will be based on mixer conversion loss and the receiver sensitivity desired.
Designing the RF front-end requires knowledge of RF and microwave circuits and perhaps impedance matching skills and amplifier design depending upon how low-level you want to get into the design process. This is not a simple task. That said, however, coaxial components are available from manufacturers such as Mini-circuits that are relatively easy to work with provided you are working relatively low frequency (~7 GHz or less).
Also, it is worth pointing out that the ADC and DACs that you choose are part of the analog front-end, and they have an associated noise figure and power requirements. As such, if you are looking to design an RF front-end, choosing an ADC/DAC might not be the way to go.
~Jeff On 6/17/2010 12:58 PM, Elvis Dowson wrote:
Hi, I would like to design a custom board based on the Spartan-3AN FPGA, based on the Spartan-3AN FPGA Starter Kit, but would like to build my own RF front-end. http://www.analog.com/en/rfif-components/rxtx-subsystems/products/index.html If I look at the AD9874 IF-to-Bits RX subsystem component http://www.analog.com/en/rfif-components/rxtx-subsystems/ad9874/products/product.html it contains an ADC and a whole bunch of other stuff. Could someone help me by pointing out what other components or parts I should be looking at to build the RF receiver front-end to start with, assuming that I am going to learn from the USRP2 design, and the fact that it already has the Spartan-3AN FPGA, and I'm going to build my own RF front-end? Best regards, Elvis Dowson
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