The multi-stage noise shaping (MASH) ΣΔ ADC has a good potential to achieve high-order noise shaping (NS) and high resolution. However, it suffers from the quantization noise leakage issue caused by the mismatch between the analog NS loop filter and the digital cancellation filter, which greatly degrades the ADC performance. The sturdy MASH structure can solve the noise leakage issue, but it cannot be directly used for NS SAR ADCs due to the structural limitations. In this paper, we propose a sturdy MASH 2-0 NS SAR to solve the noise leakage issue. The 4th-order NS is achieved by only using a 2-0 topology, which is hardware efficient. Instead of eliminating the first-stage quantization error, the proposed sturdy MASH 2-0 NS SAR shapes the quantization error, achieving better robustness to PVT variables. Furthermore, owing to the enhanced residue gain-error-shaping (GES) technique and the first-stage 2nd-order NS capability, the impairments of the residue amplifier, including the gain error, noise, and settling inaccuracy, are 4th-order shaped. Our proposed NS SAR ADC with the enhanced GES technique is implemented in a 28 nm CMOS process, which achieves a SNDR of 84.8 dB and a SFDR of 99.2 dB.