Fourth Year Projects for 2004-2005

Group Project in Integrated Radio Frequency and Analog Design

Updated Information August 21, 2004

This year, we will work on an RF transceiver, with significant emphasis on the design of a frequency synthesizer. Students will learn state-of-the-art design techniques and make use of advanced processes. Cadence-based tools, including Spectre RF, are the same as those widely used in industry so this will be valuable experience. The exact frequency of operation has not been finalized, but it will be in the GHz range. It is expected that there will be between 10 and 14 students working on this project as we will probably join forces with students reporting to Calvin Plett and John Rogers. Students will have their own blocks to design, but will also be involved in putting the whole transceiver together. Blockas are further described below, but in summary the synthesizer consists of a voltage-controlled oscillator, phase detector, charge pump, dividers, divider controller (possibly sigma-delta). There are many possible ways to build some of the blocks, so there could be several students working on variations of the same block - for example, oscillators can be LC based or ring-oscillator based. Other transceiver block that may be designed would be low noise amplifiers, mixers, filters, power amplifiers and IF parts such as automatic gain control amplfier, receive signal strength indicator, etc. Detailed design information and instructions on the use of the tools will be provided in tutorial sessions at the beginning of the term. There will also be extensive reference material - handouts for the synthesizer blocks, and reference books (e.g., the book RFIC Design by Rogers and Plett, CMOS RFIC Design by Thomas Lee) for other transceiver parts. While not mandatory, it is also recommended that students take ELEC 4505 Telecommunications Circuits. Note that currently the course is full, but if necessary, spots will be made available in the course for any of the students involved in this project.

Question: Who can get this project?

Response: Last year, basically anyone who applied for it got in. Students had a broad range of marks, although all of them ended up doing quite well in the project. Of course, if a lot of students apply for this project this year then it will not be possible to admit everyone.

Question: What other projects are similar? (I need to list other choices)

Response: The project by Prof. Rogers is very similar, in fact last year we joined forces so students could ask either one of us for help and so whenever we ran a tutorial on aspects of RF design or how to use the tools, all students could benefit from it. Other similar projects are being offered by Prof MacEachern. Aspects of projects by Prof. Tarr are also similar. Profs Wight, Syrett, and Roy typically offer projects in Microwave design, which may also make use of LNAs, mixers, oscillators and power amplifiers. The difference is typically that their designs are board level. At the board level, some emphasis is place on the design of the lines, and impedance matching, while at the integrated circuit level there is more emphasis on transistor level design (although impedance matching can still be important). If you enjoyed both ELEC 3509 and ELEC 3909, (and if you are willing to consider taking ELEC 4503 and ELEC 4502 in fourth year) then you could consider one of these microwave projects.

Question: What is the topic of this project?

Response: Details are not yet completed with what will be done this year, but it is likely to be similar to what was done in previous years, perhaps with a different standard, or different frequency. As an example, a few years ago, we were working on Bluetooth radios at 2.4 GHz, last year we worked on a 5 GHz design done for wireless LAN. As for process technology, in 2003-2004, the design was done in a SiGe BiCMOS process in which the ft of the bipolar transistors was about 50 GHz. This will probably be the process used again this year. Prior to last year, the design was done with 0.35 micron CMOS. In some years the students made so much progress we made some presentations. For example, in 2001-2002, some of the students presented a poster at the CMC workshop, then later presented their project to Conexant and as a result a few of them were invited to work for Conexant. You can see their poster presentation posted next to the elevator on the fifth floor Mackenzie Building. As well, more details can be found in the 2001-2002 web page .

Question: What circuits could we be expected to design/build?

Response: Whatever the exact radio standard we follow and whatever process we use, the expected components are listed below (and a paragraph on each is found further down on this page). Typically we meet at the beginning of the term, go over the possible components, then everyone discusses the project and picks a particular component to work on. This being a group project, there will be aspects that everyone does as a group, but you will get to do your own design as well.

Question: What steps will we follow in this project?

Response:

Plots of a RFIC Design from a few years ago

Question: What background is required?

Response: The most important part is that the student enjoy doing circuit design. If you enjoyed ELEC 3509, you are the right person for this project. Background theory is provided by the third year courses, Electronics II (ELEC3509) and to a lesser extent Communications theory (SYSC3501). Further theory will be provided by some of the fourth-year courses, e.g., Telecommunications Circuits ELEC4505.

Question: Are there reference texts I can study?

Response:

Rogers and Plett, Radio Frequency Integrated Circuit Design , Artech House, 2003

Thomas Lee, CMOS Radio Frequency Circuit Design, first edition about 1999, Second Edition, about 2003

Sedra and Smith Electronics fourth edition, fifth edition 2003

Question: What simulator/tools will we use?

Response: Most of the design is done using Cadence Software. This is the same software as industry uses, so experience in it is valuable. You will use it to draw schematics, use it to simulate these schematics (using a simulator called Spectre within Analog Artist). This tool will also be used to do circuit layout (drawing transistors, capacitors, inductors and connecting them all to each other.) This tool will also be used to do design rule checks, comparison of layout versus schematics to ensure you have designed the right circuit, and extraction of parasitic capacitance to predict how well the actual circuit would work. Other tools which are sometimes used are HPADS another circuit simulator, similar to Spectre but with different strengths, weaknesses, Momentum to do electromagnetic simulations for example of inductors, Matlab or analog HDL to do system level simulations.

Question: What are the deliverables and milestones through the year?

Response:

Here is some More Details on Some of the Parts.

1. Radio Frequency Mixer Design

In a radio-frequency front end, the incoming signal at the radio frequency (RF) is converted to the intermdediate frequency (IF) by mixing with a local oscillator (LO) signal. Thus the mixer inputs are the RF and LO signals and the output is the IF signal. Typically, many RF signals may exist, but only one is desired. This means that one of the main concerns in a mixer is linearity of the RF input to prevent intermodulations between various input signals. Other issues of importance are frequency response, power dissipation and noise.

This project will begin with a study of different types of mixers. The study could involve simulation to evaluate the linearity, and other specifications of the different structures. Then a particular design will be chosen for detailed analysis and design, followed by implementation and test.

2. Radio Frequency Oscillator Design

Oscillators are used in several ways in Radio Frequency circuits, for example as an input to a mixer which converts from the radio frequency to the intermediate frequency. Usually, the oscillator frequency is adjustable (Voltage-Controlled Oscillator or VCO) and used inside of a frequency synthesizer. One of the biggest concerns in oscillators is noise components which can cause the wrong frequencies to be mixed down to the intermediate stage.

This project will begin with a study of the background material and of possible oscillator topologies. This will be followed by simulation, for example, to determine which type of oscillator results in the lowest noise. Then, a particular topology would be chosen for more detailed study of the design tradeoffs, followed by implementation and test.

3. Radio Frequency Power Amplifier Design

Power amplifiers are used to drive the antenna on the transmit side. Difficulties in design are achieving high enough power while using a battery as a power supply. High efficiency is important in order to maximize life of the battery. Different classes of amplifiers (from class A through class F) can be chosen with different tradeoffs between efficiency, linearity and simplicity of design.

This project will begin with a study of the different classes and types of power amplifiers. Part of this might also be to consider linearization techniques. This will be followed by simulation, to determine which type of amplfier can meet the desired specifications, for example, which has the highest efficiency and what the tradeoffs are. Then, a particular design, or combination of designs will be chosen for detailed analyis and design, followed by implementation and test.

4. Radio Frequency LNA Design

The LNA provides amplification close to the input without adding too much noise. This means that noise added by later stages is of less importance. Thus the main issue is noise. Other things are also ofconcern. For example, the input impedance must be matched to the antenna. Linearity must be sufficiently high to avoid overloading in the presence of high amplitude signals, which could be present at nearby frequencies, while still receiving potentially low amplitude wanted signals. Other important design considerations are power dissipation, layout area etc.

This project will begin with a study of different types of LNAs. The study will involve simulation to evaluate the noise, linearity, and other specifications of the different structures. Then a particular design will be chosen for detailed analysis and design, followed by implementation and test.

5. Synthesizer Design

In a radio communication system, one can typically communicate on one of many channels. In a radio front end, the synthesizer sets the local oscillator frequency to tune in the desired channel. Thus the synthesizer contains a voltage-controlled oscillator (which is a project of its own) but also adds the control circuitry to set the frequency and to allow selection of frequency. Synthesizers can be based on phase-locked loops, of which there are several variants, or can be direct digital (where the equivalent of sine waves are stored in memory and read out at an appropriate rate to produce the desired signal). Issues in synthesizers are switching speed, resolution, tuning range, etc.

This project will begin with a study of different types of synthesizers and of the blocks that make up a synthesizer. Since a synthesizer can be quite complicated, typically a few people will work together to design a complete synthesizer (blocks could be charge pump, phase detector, oscillator, dividers, controllers). Simulations will start with higher level simulations of the whole synthesizer, followed by more detailed simulatiosn for the particular block chosen.

Courses most strongly related to the project