A 19bit 20digital to analog convertor(DAC) is designed in UMC 0.18um CMOS technology with 1.8V power supply. The DAC includes a single-loop multi-bit ΔΣ modulator and a switched capacitor filter. According to the simulation in spectre-verilog, it can realize 17.22 bit resolutions under 64 times over-sample ratio while in 5-bit quantization. The power used in analog part is only 6.9mW, considering digital part’s consumption, FOM value is smaller than 3 pJ/step; The whole chip size including PADs is 1.4mm1.6mm.Key words: DAC, ΔΣ modulator, SCF, FOM