Analysis of multi-port amplifier calibration for optimal magnitude and phase error detection

This study presents theoretical analysis and verification on optimal hardware platform for calibration of signal manipulation in multi-port amplifier (MPA). Since MPA output power and isolation characteristics are strongly dependent on magnitude and relative phase balances in each array path of MPA, proper calibration technique is necessary for ideal MPA operation. Although variety of calibration methods can be considered, they can be classified into two methods from the calibration signal detection based on hardware platform point of view. That is, calibration signals for each array path in MPA can be sampled and detected before output hybrid matrix (OHM) or after OHM according to hardware setup. Since optimal signal detection for each array path is the key to ideal MPA calibration and maximised performance, this study theoretically analyses two different calibration hardware platforms detecting calibration signals. Then, the mathematically derived optimal calibration hardware setup for detecting magnitude and phase error is finally verified and concluded by simple simulation and measurement at 900 MHz Industrial, Scientific and Medical-band (902-928 MHz).