A Sampling Switch Design for Liquid Crystal Displays

In the design of an active matrix LCD, the ratio of the pixel voltage to the video voltage, abbreviated to RPV, is an important metric of the performance, since the pixel voltage determines the transmitted luminance of the pixel Hence, in the design of a source driver circuit for an LCD, of primal importance is the issue of how to restrict the admissible allowance of the RPV of a pixel within a specified narrow range. This constraint on the RPV is analyzed in terms of parameters associated with the sampling switch and the sampling pulse, and then by using a minimal number of these parameters, a design scheme is described dedicatedly for the sampling switch, which finds an optimal sampling switch size and an optimal sampling pulse waveform. Experimental results show that an optimal sampling switch attained by the proposed scheme gives rise to a source driver with almost 50% less power consumption than the one by manual design.