Low-Power Differential Input to Single-Ended Output GaN RF-DAC for RF-Signal Generation

A low-power differential input to single-ended output digital-to-analog converter (DAC) is presented, which is capable of providing radio frequency (RF)-signals with a data rate of up to \mathrm {8~G} bit/s. A constant direct current (dc) current source is realized as a self-bootstrapping device in the presented 0.25- \mu \text{m} in-house gallium nitride (GaN) technology. First, measurements with a low-power [1-V peak-peak voltage ( V_{pp} )] differential input signal show the feasibility of switching constant currents with a clock frequency of up to 2 GHz. Furthermore, a 2-b DAC that uses a differential sampling to generate RF-signals is introduced. Measurement results prove the feasibility of synthesizing custom-modulated voltage waveforms with data rates of up to 8 Gbit/s in the sub-6-GHz frequency range.