Optimization of LCD Driver Design by CAE

Abstract

A new circuit configuration was proposed for the output amplifiers that drive LCD loads in mobiIe telephones, to reduce the power consumption of the LCD driver circuits. The objective function of these output amplifiers is current amplification of an input signal, but circuit simulation of the new configuration showed an unwanted input-output voltage difference, and it was confirmed that this difference increased with increasing temperature. The output voltage determines the transmittance of an LCD, so a voltage difference has a direct effect on image quality. The temperature dependency of this difference is a quality problem that lies beyond the scope of quality assurance. Parameter design was carried out by combining circuit simulation with quality engineering to reduce the voltage difference. Performance goals were attained in the short time of about thirty hours.