A Measurement Summary of Distributed Direct Sampling S-Band Receivers for Phased Arrays

This article details performance measurements vs. predictions of a 16-channel S-band direct sampling receiver design. The design is based on recently released direct sampling analog-to-digital converters (ADCs) clocked at 4 GSPS and sampling in the second Nyquist zone of the converter. The design configuration is first described with pointers to online references that provide further description. Next, the receiver is shown for both the RF components and the configuration of the embedded digital signal processing (DSP) that is now integrated into modern data converters. Calculations for single-channel performance predictions are presented and compared against measurements. With the single-channel performance understood,a set of measurements combining data from 16 channels evaluates the dynamic range improvements for noise density, spurious signals, and inter-modulation products. The article concludes with a set of observations for the multichannel performance trends that can be used for extrapolation to models of large phased arrays implemented with many distributed receivers.