Fig. 1. Block diagram of ideal vector modulator

Fig. 2. Black diagram of non-ideal vector modulator model

Fig. 3. Mapping relationship between the input and output of non-ideal VM (color online)

Fig. 4. Logical architecture of RF experimental setup (a), and snapshots of digital board (b), analog board (c), and CPCI-based LLRF (d)

Fig. 5. Screenshot of OPI

Fig. 6. VM output track before and after calibration (color online)

Fig. 7. Variation of the VM output amplitude with the setting phase before and after calibration (a), VM output amplitude after calibration and white noise (b), error between VM output phase and setting phase (c)