Design of High Performance Regulated Charge Pump Circuit

Motivated by emerging portable applications that demand ultra-low-power hardware to maximize battery run-time, and high-efficiency low-voltage DC-DC conversion is presented as a key electrical device.
Charge pump circuit has been shown to be a critical DC-DC converter for low-battery voltage technology in mobile equipments with color displays.
This thesis introduces and demonstrates an array of regulated charge pump design techniques which make the power system of display high efficiency, high performance, and compact. The primary design challenges to high-efficiency high-performance regulated charge pump are summarized. Design techniques at the power delivery system, individual control system, and circuit levels are described which help meet the stringent requirements imposed by the portable environment.
The research is focused on portable display-driving applications, where small size, low cost, and high energy efficiency and performance are the primary design objectives.
The design and measured results are reported on three regulated charge pumps which include voltage and current regulations, and successfully demonstrate the design techniques of this thesis. Description as follows:
1. High-voltage positive and negative charge pump as ± 6×VDD with voltage regulated to powering gate drivers of TFT-LCD drivers for their individual loads, can provide up to 17.5V and -14.5V in overall input voltage range of mobile equipments. Nine-phase clocks pumping is proposed to reduce one external flying capacitor for cost-efficient. Special design for the negative regulated scheme using differential difference comparator has been introduced, which increases accuracy of the negative regulated voltage, and reduces power consumption and chip area.
2. The lowest voltage-ripple design applied to a regulated voltage doubler is used to reduce the output ripple voltage for powering source drivers of TFT-LCD drivers. Multi-phase operation is proposed to minimize the output voltage-ripple, and this is with a 28 mV output voltage-ripple by up to 20mA load current. It delivers a regulated voltage from 4.5V to 5V with 1μF flying and load capacitors. Design equations and closed-form expressions for low ripple regulated charge pump are presented.
3. The high power-efficiency current-regulated charge pump is proposed to drive WLED for extension at low battery voltage and decreasing chip area.
As the result, the approach presented in this thesis is evidently viable for realizing compact and highly efficient DC-DC converters for used as low battery-voltage power systems to powering display drivers in portable electronic applications.