Fourth Year Projects for 1998-99

Poster Session done by Fourth Year Project Students

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 will involve simulation with a combination of HPEESOF and SPICE 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.

This projects assume a good understanding of background theory as provided by the third year courses, Electronics II (97.359) and Communications (94.351). Further theory is provided by some of the first-term fourth-year courses.

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, probably with HPEESOF, 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. This will be followed by simulation, probably with HPEESOF, to determine which type of amplfier results in 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.