A digital phase shifter for multiple pulse NMR

An eight bit digital phase shifter is described which is suitable for multiple pulse NMR of solids in terms of settling time (≂2 μs) and phase resolution (1.406°). The unit incorporates an 8‐bit Merrimac digital phase shifter model PSDW‐84‐1, and an amplification‐damping‐pulse shaping circuit to solve the problem of variable attenuation as a function of phase setting. Results of multiple quantum spin counting and homonuclear dipolar decoupling experiments on ensembles of strongly dipolar coupled spin 1/2 systems are used to demonstrate the capability of the unit.