An Incremental Phase Shifter and Frequency Modulator for Magnetic Resonance Imaging and Spectroscopy

A digitally controlled analog phase shifter is described for the application in magnetic resonance (MR) imaging and spectroscopy. The design is based on a single side band modulator scheme. A phase resolution of 1.4°and a switching time of 400 ns are achieved. The device controls the phase of the intermediate frequency in the MR instrument, and hence can be used over the entire observe frequency range of interest.