Ultra-Low Power Timing Circuit (ecULP-TCTM) At the center of most operational systems is TIME. Time enables us to communicate, to synchronize, to control, and to position. An accurate, reliable, low size, weight and power timing source is critical to our esc Aerospace NavXTMsolution for accurate and reliable PNT in total GPS denial, but it is equally critical in a vast number of other military and commercial applications including communications, targeting, IoT, etc. Crystal Oscillators continue to be the de facto standard for timing. They are very affordable, small, and low power consumers. However, as technologies advance, and GPS signals are threatened, there is more and more demand for increased timing circuit performance. New technologies have been developed that provide superior performance, but at a significant cost. At the highest end are Chip Scale Atomic Clocks. Oven and Temperature Controlled Crystal Oscillators provide performance improvements but are larger power consumers. Our escULP-TCTM is a circuitry-based approach (vs. materials) that bridges the gap between XOs and CSACs. escULP-TCTM target performance: .1 ppm.1-1 ?W. When integrated into our NavXTM PNT solution, this performance will enable >24hr holdover time and positional accuracy in total GPS denial. Most importantly, without adding any additional power. Our current Phase II SBIR project has develop a prototype chip that exceeds our performance objectives. See 100 sec video: https://www.youtube.com/watch?v=MELtysgoa08(link is external)