A low-voltage low-noise DC-DC flyback converter with delta-sigma modulation

Comparing with buck-boost converter, flyback converter has positive output voltage in switching mode converters, therefore, flyback converter is easier to supply voltage for the rear-end application circuit. The delta-sigma modulator takes important advantage of the noise-shaping and oversampling properties to eliminate the spike in DC-DC flyback converter. Also, comparing with pulse width modulation (PWM), the proposed two-order delta-sigma (ΔΣ) modulator has strong ability of improving the noise rejection in switch-mode converters. It supplies more steady energy to sensitive circuits such as audio amplifier or power amplifier. Because of low-voltage design, the inverter-based operational amplifier is proposed in this work, which can keep operational amplifier good performance. The input voltage of the proposed circuit is 1.5V, and the range of output voltage is from 1V to 3.3V. The chip area is 2.24 × 2.24 mm².