Abstract: This paper presents a single-loop 3rd-order 4-bit Continuous-Time Sigma-Delta modulator using the Matlab toolbox. Compared with Discrete-Time modulators, continuous-time modulators are sensitive to non-ideal factors, but they have outstanding performance in terms of power consumption and bandwidth. In the design process, a zero-order feedback loop is added to absorb the excess loop delay, and the three main non-ideal factors of the continuous-time modulator are analyzed. Finally, based on the 65nm CMOS process, the circuit and layout of the modulator is completed. Through spectre simulation, the modulator can achieve 78.20dB signal to noise and distortion ratio with bandwidth of 10MHz, while the power consumption is only 5.39mW.