Load Board Designs Using Compound Dot Technique and Phase Detector for Hierarchical ATE Calibrations

This paper presents two load board designs for hierarchical calibration of largely populated ATE. Compound dot technique and phase detector are used on both boards to provide automatic and low cost calibration of ATE with or without a single reference clock. Two different relay tree structures are implemented on the two boards with advanced board design techniques for group offset calibration. Various error sources have been identified and analyzed on both boards based on SPICE simulations and real measurements. TDR measurement compares the two approaches and shows that the two load boards give a maximum of 37ps group timing skew and can be calibrated out by the calibration software