Method for setting transistor operating point and circuit therefor, method for changing signal component value and active-matrix liquid crystal display device

摘要

A data signal voltage on a signal line 102 is held in a voltage holding capacitor 106 through an n-type MOS transistor 103 switched on by a gate scan voltage, and supplied to an analog amplifier circuit 104-1. The analog amplifier circuit 104-1 is formed of an MOS transistor having a double gate structure, and the operating point thereof is set at an operating range in which dependence of Ids on Vds is substantially nullified. Even when Vds is varied due to a response of liquid crystal 109, Ids is substantially fixed. Accordingly, the pixel voltage which is substantially proportional to the data signal voltage can be applied to the liquid crystal 109.