A Traveling-Wave ADC based on spatially interleaved sampling on a synthetic transmission line is proposed. Signal propagation on the transmission line generates the interleaving delay. This architecture enables extremely small sampling periods which allow for high sampling frequencies. Furthermore, the loaded T-line provides a broadband input impedance to enable extended input frequencies. The design tradeoffs are presented and the main challenges and opportunities in spatial interleaving are discussed. The relationship between transmission line parameters and the ADC specifications is investigated through a design example.