On chip digital-to-analog converters for ultrafast signals using spintronic terahertz emitters

We demonstrate a proof-of-principle for a device in which we can realize binary encoding of the amplitude of an ultrafast signal similar to a multiplying digital-to-analog converter. The device was developed using multiple on-chip spintronic THz emitters with different respective emission amplitudes and coercive fields, representing the different bits of the digital-to-analog converter. A resolution of up to four bits with an integral non-linearity of less than 2 least significant bits could be achieved. Although programming these demonstrators is a slow process, spin-transfer torque switching can easily move the switching frequency to the GHz regime.