Advanced Design System CAD project

Circuits for radio frequency applications are becoming increasingly complex, and their design requires the use of increasingly powerful CAD tools. These tools are no longer limited to considering the circuit alone, but also consider it in its environment. ADS (Advanced Design System) software has been specially developed to simulate signal behavior in all stages of a communication system. The proposed training course is designed to introduce designers to the simulation of a complete transmit-receive system dedicated to mobile telephony applications (GSM 1800).

This training enables a person familiar with the various electronics functions to use them under real operating conditions, and to observe the impact on the system as a whole of varying a parameter in one of the blocks performing the function. For example, in the case of GSM system simulation, among the important blocks to consider are:
- propagation channel,
- signal propagation conditions (urban, non-urban, semi-urban)
- transmit and receive amplifier parameters (gain, noise figure, compression point, third-order intermodulation product)
- transmit and receive antennas (mobile or fixed antennas)
- digital filters (stiffness coefficient, cut-off frequency)
- local oscillators (phase noise)
- mixers (linearity)

This systems approach to the designer's job is a comprehensive illustration of what is taught in electronics (digital transmissions, modulation techniques, amplification functions, digital filtering). It draws on both analog and digital knowledge. It also introduces students to measurement techniques and the interpretation of observed results: the tools available for visualizing signals in both the time and frequency domains include the eye diagram, state constellation, spectral analysis, time analysis (bitstream) and bit error rate measurement.

Contents: simulation of a digital system
1. Simulation of QPSK digital modulation
- eye diagrams,
- state constellation,
- I and Q signals,
- spectra of modulating signals.
2Simulation of a wireless transceiver system for radiotelephony applications at 1.8 GHz
- QPSK modulation and demodulation
- RF transceiver system