This brief presents a leakage-tolerant high-resolution reconfigurable RC-to-digital converter (R²CDC) that can readout multiple resistance/capacitance sensors using swing boosted period-modulation (SB-PM) front-end. This R²CDC employs SB-PM front-end and first-order noise shaping block that results in 23.03aF Abs. Resolution. Compared to the conventional design, the leakage current was reduced by at least 15.67 times. Implemented in a 0.18µm standard CMOS process, the proposed (R²CDC) consumes 56.38µA from a 1V supply, occupying an active area of 0.0275 mm², achieving FoMs=4.58μJ∙ppm₂, FoMw=0.359pJ/Step efficiency at a measurement time of 500µs.