This paper analyzes the relationship between the total output noise power and loop filter coefficients variation of continuous-time delta-sigma modulators. Based on the analysis, a new calibration technique utilizing the total output noise power to improve the loop filter inaccuracy caused by PVT variation is proposed. This proposed calibration method is implemented in the digital domain and requires only capacitor arrays in analog loop, minimizing the hardware cost and the excess loop delay. The calibration technique is verified by a third-order delta-sigma modulator post-layout simulation results. The peak signal-to-noise-and-distortion ratio (SNDR) increased by 4.5dB after calibration.