| 摘要 |
<p>A voltage regulator circuit for a liquid crystal display in which compensation for the temperature dependent nature of the operating characteristics of the display is achieved using integrated circuit components. This is achieved by utilising the temperature-dependent characteristics of a forwerd bias PN junction diode (323, 324), the number of diodes providing selection of the temperature gradient of the output voltage. The PN junction diode may be formed, effectively, by an NPN transistor 305 with its base and collector terminals common. Alternatively the temperature dependent element may be formed as an integrated resistor (362, 366). The entire circuit is made as an integrated circuit, preferably using MOS technology, and adjustment of the temperature gradient of the output voltage and the voltage level thereof are provided for by techniques compatible with integrated circuit structures. In one embodiment a non-volatile memory device (461, 462) is used to control a set of analogue switches (421-424; 451, 454) in series with respective integrated resistors (401, 404; 431, 434). The output voltage is stabilised by providing a standard voltage source within an operational amplifier, for example utilising the difference in the threshold voltage between two MOSFET, so that the output voltage is not affected by variations in the supply voltage. In order to reduce the power consumption to a minimum the operational amplifiers may be cyclically activated by a periodic clock signal and a sample and hold circuit (396, 397) is provided.</p> |
