Integrated BiCMOS control circuits for low-power current-mode DC-DC boost converter

This paper introduces the design of integrated BiCMOS current-sensing circuit and amplifier for high-performance DC-DC boost converter. By exploiting the advantage presented by the integration of both CMOS and bipolar devices within same technology, the BiCMOS circuits offers high gain amplifier and accurately sensed inductor current. The error amplifier has BJT differential pair and current sources to obtain a fast response, while the current-sensing circuit exploits a current-mirror instead of op-amplifier as a voltage follower. The test in 0.35 μm BiCMOS process shows that the transient time of the error amplifier is controlled within 10 μsec and the current-sensing circuit can operate with accuracy of higher than 90 % at the frequency from 10 KHz to 200 KHz. The output voltage of 5.5 V is obtained with the ripple ratio within 2%.