RF Signal Generation with Digital Up-Converters in AWGs

Arbitrary Waveform Generators (AWG) have always been incorporated in RF signal generation systems to generate complex modulations, analog or digital. Traditionally, AWGs generated real or complex (I/Q) base-band signals to feed modulators. In particular, quadrature (IQ) modulators combined with 2 -channel AWGs can generate any analog or digital modulation, provided the modulation bandwidth of the modulator and the bandwidth/sampling rate of the AWG are sufficient to faithfully generate the desired signal.Any imbalance, quadrature, I/Q skew, etc. reduces the modulation accuracy, the available noise floor, and the usability of the generated signals. This issue grows exponentially with modulation bandwidth, so it is sometimes the most critical and costly factor for Vector Signal Generators.A modulated RF signal, even for low modulation bandwidths, may require a huge number of samples to keep the required Time Window. Generating the same modulation at a different carrier frequency requires calculating and downloading a new waveform so the new carrier frequency (properly quantized) can be implemented .

This document will cover in depth how real-time digital up-conversion (or DUC) and Digital down-conversion (or DDC) is applied to improve the usability, accuracy and RF performance while offering the best -in-class modulation and analysis bandwidths while supporting full coherence and phase control over tens and even hundreds of channels.