Modern RF systems like superconducting quantum bit controllers, phased-array radar, MIMO transceivers, smart antenna transmitters, and agile ultra-wideband spread spectrum telecommunication are based on wideband, coherent, multi-channel architecture. The traditional method using vector signal generators with IQ modulators and analog synthesizers for RF signal generation pose major limitations due its calibration complexity and cost for largescale implementation of such systems.
As a solution to this, a class of high-speed digital-to-analog converters is emerging that embody signal processing, modulation, and generation functionalities. These data converters are capable of directly synthesizing complex signals at microwave frequencies. They also allow for simpler multi-channel synchronization and calibration and offer a significantly lower cost for systems with high channel density by eliminating the need for complex analog front-end. For example, Tektronix AWG5200 series arbitrary waveform generators utilize such digital-to-analog converters and offer up to 8 synchronized channels per instrument that is further expandable by synchronizing more instruments.
In this document, some important features enabling the AWG5200 series for direct RF complex signal generation are presented followed by a discussion on two architectural techniques that can be implemented externally to further expand the frequency coverage of the instrument with a focus on reducing cost and complexity for multi-channel applications.