SFDR Considerations in Multi-Octave Wideband Digital ReceiversWhitepaper
August 02, 2021
Electronic warfare (EW) receivers must intercept and identify unknown enemy signals among a congested wideband spectrum of multiple interfering signals without the benefit of dynamic range and sensitivity improvement techniques employed in communications and radar receivers. The incident RF band limiting employed in communications receivers is an unwanted trade for the EW receiver that seeks to process ever wider instantaneous bandwidth in less time. In the radar realm, receiver dynamic range benefits from matched filtering, whereby the received radar return is correlated with a copy of the transmitted signal. Alas, the EW receiver has no prior knowledge of the signal to be intercepted and thus nothing with which to correlate! It’s like searching a crowd of people for a stranger you’ve never seen before ... and worse yet, he is hiding, or maybe isn’t even there!
Now for the good news: over the coming years, high sample rate analog-to-digital converter (ADC) and digital-to-analog converter (DAC) technology will usher in a wideband digital receiver architectural evolution. Most importantly, converters from Analog Devices will maintain the excellent linearity, noise performance, and dynamic range of legacy lower rate digital converters. The workhorse super- heterodyne tuner will give ground to direct sample and direct conversion architectures.1 Adaptive spectral tuning will continue to shift from the RF to the digital signal processing realm.