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Design >> Mixed-Signal Design >> Digital modulation, ADC design, and RF section design questions
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Message started by DavidX on Jun 21^st, 2015, 2:45pm

Title: Digital modulation, ADC design, and RF section design questions
Post by DavidX on Jun 21^st, 2015, 2:45pm

I am a master student and studying RF system design. Now I have some questions about Digital modulation, ADC design, and how those effect the requirements of RF circuits and systems, If anyone can tell me, I will appreciate it. My email: xyang066@yahoo.ca

1. When designing an RF system to handle digital modulations list the RF characteristics that will have the greatest impact on the final signal to noise ratio of the system?

2. What techniques can be used to extend the dynamic range of analog to digital and digital to analog converters? How does this impact on the design of the RF sections?

3. A radio is failing to meet sensitivity requirements, how would you go about the debug process to determine the part of the design that is at fault?

4. In a direction conversion transmitter and receiver what are the typical system issues that need to be overcome to reliable transmit and receive high order QAM modulations?

Title: Re: Digital modulation, ADC design, and RF section design questions
Post by Tako on Jun 22^nd, 2015, 12:33pm

You should find answers to all your questions in textbooks or books recommended during your RF course.

I can help you a little regarding question 2. To quote Wikipedia (https://en.wikipedia.org/wiki/Analog-to-digital_converter)

Quote:

The dynamic range of an ADC is influenced by many factors, including the resolution (the number of output levels it can quantize a signal to), linearity and accuracy (how well the quantization levels match the true analog signal) and jitter (small timing errors that introduce additional noise). The dynamic range of an ADC is often summarized in terms of its effective number of bits (ENOB), the number of bits of each measure it returns that are on average not noise. An ideal ADC has an ENOB equal to its resolution.

If you would like to understand ADCs more in order to logically remember what is linearity or accuracy etc., I remember that you'll find quite good summary of ADC parameters in Baker book.
Simple explanation of some basic ADC parameters can be found also here: http://www.mtcmos.com/list-of-adc-parameters/
This one also looks quite good: http://www.embedded.com/design/configurable-systems/4025078/Understanding-analog-to-digital-converter-specifications .

Good luck!

Title: Re: Digital modulation, ADC design, and RF section design questions
Post by DavidX on Jun 22^nd, 2015, 3:11pm

Thank you so much, Tako. It is very helpful.

DavidX