This invention discloses a voltage generator circuit having a voltage regulator and a voltage generator for supplying voltage to a load. The voltage regulator is powered by a power source which supplies a first voltage level and the voltage regulator provides a regulated output at a second voltage level lower than the first voltage level. The voltage generator receives power from the regulated output and provides a multiplied output having a third voltage level. Therefore, any level of voltage between the first voltage level and the third voltage level is available to the load circuit. Since the voltage regulator supplies the voltage generator with power at a regulated level, the voltage level applied to the muliplier may be adjusted for conserving power.
The present invention relates to electronic circuits, such as an operational amplifiers, which have dual power supply requirements. When the power supply voltages are switched between an "off" state and an "on" state, the power supply transient voltages of the two polarities closely track each othe so as to reduce audio transients from being produced within the operational amplifiers. This tracking is accomplished by the negative polarity power supply voltage being provided for the signal amplifier at the output terminal of an unity gain operational amplifier having an inverting input terminal coupled to the positive polarity power supply voltage.
In a driving circuit for a liquid crystal apparatus, a DC offset voltage the level of which changes depending upon the level of input video signals is applied as an input video signal. The DC voltage which appears in the liquid crystal and the level of which changes depending upon the level of input video signals can be completely compensated.
A liquid crystal display apparatus detects and regulates its display contrast. A liquid crystal display unit is provided therein with a pair of liquid crystal cells for use in detection of the display contrast. Incident light is detected through the cells, and the detected results are fed back to control a drive voltage applied to the liquid crystal display unit so as to automatically regulate the display contrast at optimum level.
A method and apparatus for automatically controlling integrated circuit supply voltages includes, according to one embodiment, a primary voltage regulator and a secondary voltage regulator. The primary voltage regulator supplies one of either a first voltage or a second voltage to a first plurality of inputs of an integrated circuit. The secondary voltage regulator conditionally supplies a third voltage to a second plurality of inputs of the integrated circuit in the event the primary voltage regulator supplies the first voltage, with the third voltage being substantially the same as the second voltage.
