| Portable electronic equipments are widely used in people's life with the rapid development of integrated circuit design technology and semiconductor manufacturing technology. In order to meet various application needs, new design challenges of the power driver are present, such as providing stable output voltage over the wide supply voltage range, keeping high efficiency whether the load is light or heavy, and less peripheral devices.A power driver based on BUCK-BOOST topology is proposed in this thesis, whose maximum load current is 100mA with a 2.4 to 5.5V supply voltage. It can provide a fixed 4.6V positive output voltage and an adjustable negative output voltage down to -6V. Good transient response performance is achieved by adopting peak-current control mode, and line regulation and load regulation are greatly improved thanks to the dual control loops composed of external voltage control loop and internal current control loop. Besides, PFM is employed to keep high conversion efficiency, and the driver can switch between CCM and DCM automatically according to the load current, which guarantees high efficiency over the whole load range; In addition, synchronous rectification is adopted to improve efficiency further.In this thesis, basic theories related to BUCK-BOOST converter are introduced firstly, such as basic operation principles, voltage control mode,peak-current control mode, synchronous rectification and power stage model; Secondly, the implementation scheme of whole chip is proposed on the basis of the system functional requirements, and some sub_blocks are given, such as error amplifier,compensation circuit, bandgap voltage reference and analog comparator; In addition, the concrete circuits and the operation principles of key sub_blocks are introduced completely and the performance is simulated and validated by HSPICE.Lastly,the function and performance of the whole chip are simulated and verified, and the results meet the original design object well. |
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