The Design And Implementation Of Follower For CSTN Liquid-Crystal Display Applications

At present, CSTN-LCD occupies a larger market share of portable electronic products because of its low-power, low-cost advantage. The design of the follow is one of the important and difficult point in CSTN-LCD. The follow of CSTN-LCD need to have the following performance requirements: low-power, high slew-rate, high power supply rejection ratio; can drive the large dynamic capacitive load.The follow is applied to 160 columns * 132segments CSTN-LCD driver chips of Hi-Fas scan mode. The scheme of charge-discharge auxiliary module is used in order to meet the system requirements of low power consumption and high slew rate simultaneously. Static power consumption does not exceed 35uA, the charge and discharge time is less than 15 us. And cascade frequency compensation is adopted in this design to obtain a better frequency response characteristics. DC gain is 80 dB, unity gain bandwidth is 100 KHz, and the phase margin is 90°.Floating gate current source is introduced to make the circuit more compact. The area of this design is less than 600 * 100 square microns. This design has a good performance in power supply rejection ratio. PSRR is greater than 30 dB in 1 MHz frequency.