We demonstrate a high-speed silicon carrier-depletion Michelson interferometric (MI) modulator with a low onchip insertion loss of 3 dB.The modulator features a compact size of <1 mm2 and a static high extinction ratio of >30 dB.The Vπ · Lπ of the MI modulator is 0.95-1.26 V · cm under a reverse bias of-1 to-8 V,indicating a high modulation efficiency.Experimental results show that a 4-level pulse amplitude modulation up to 20 Gbaud is achieved with a bit error rate of 6 × 10-3,and a 30 Gb/s binary phase-shift-keying modulation is realized with an error vector magnitude of 25.8%.