We describe a new approach to Johnson Noise Thermometry (JNT) that addresses certain limitations found in the conventional approach. The concept takes advantage of recent advances in digital synthesis and signal processing techniques together with advances in Josephson voltage standards. By using the perfect quantization of voltages from the Josephson effect, a synthesized broadband waveform can be used as a calculable noise source for calibrations. A collaboration between NIST and MSL explores this approach with the initial goal of creating a JNT measurement system capable of achieving relative accuracies of 0.001% in the range of temperatures between 84 K and 430 K. In this paper, we discuss the use of a broadband Josephson waveform generator to produce a calculable reference noise source, the related metrological challenges, the technical advantages conveyed by this approach, and the commensurate opportunities to advance the state of the field.