| IP개요 |
With the rise of portable devices such as laptops, smart phones, and tablets, size and performance becomes critical factor for power IC design. In DC-DC converter design, the most inconvenient and cost in switching inductor converter design is the inductor size. In order to reduce the inductor size yet still keeping the converter performance, high switching frequency should be used. Voltage mode converter is not favored because of its bulky compensation components. For current mode converter type, however, the current sensor shows limited performance, according to reported studies. In [2] and [3], a method to sense high speed inductor current accurately was reported, yet still incompletely: 1) The sensing method still depends on the off-chip inductor, which can have 30% tolerance; and 2) the amplifier offset, which cannot be eliminate by auto-zero, or offset-cancellation method, will contribute to large error to the sensing output. This design is to implement an area-saving inductor current sensor with trimming circuits dealing with the problem mentioned above. In addition, by detecting large change of the DC inductor current, maximum/minimum charging can be implemented to enhance transient performance. Finally, a low current, yet with high PSRR band-gap reference is proposed. |
