Architectures for Software-Defined Radio Transmitters• Radio Transmitter: The transmitter itself generates a radio frequency

alternating current, which is applied to the antenna. • Several transmitter architectures have potential application to the

SDR systems.• The Front End: A transmitter is not only a power amplifier but also

have circuit components collectively known as the Front End.

Super-heterodyne Transmitter

• This architecture is adopted for microwave point-to-point wireless links as, for example, in backhaul communications.

• The amount of circuitry and low integration level as well as required linearity of the PA and the difficulty to implement multimode operations generally prevent the use of super-heterodyne transmitters in SDR applications.

Direst-Conversion Transmitter

• Reduces amount of circuitry.• Improves high level integration.• Gain can be carried out at RF.

Power Amplifier Section

Test of Software-Defined Radio Solutions• Key to this discussion is the concept of a mixed-domain measurement

technique.• The main idea is to push the ADC/DAC as close as possible to the

antenna.• As a result, fewer signals will exist in Analog domain and the

measurement of digital signals takes on a level of importance not found in traditional analog RF system characterization.