Texas Instruments Corporation

Tsuyoshi Chimura

Masahiko Higashi

Tatsumi Satoh

The object of this invention is to realize high-speed rise and/or fall characteristics for amplifier without increasing transistor size or current consumption. A first rise sensing circuit and a second a sensing circuit are connected to main circuit . The first sensing circuit has a PMOS transistor which functions as a rise sensing transistor, a pair of NMOS transistors and , which form a current-mirror circuit, and a PMOS transistor , which drives the PMOS transistor used for speed up in main circuit . The second sensing circuit has a PMOS transistor , which functions as a fall sensing transistor, a pair of NMOS transistors and , which form a current-mirror circuit, and a PMOS transistor used for driving the PMOS transistor used for speed up in main circuit

High speed amplifier

An operational amplifier with improved operational speed, as well as low power consumption, arranges a current mirror made of the pMOS transistors PT.sub.17 and PT.sub.18 in the stage after the initial-stage differential amplifier, supplies the output of the initial-stage differential amplifier to the gate of the nMOS transistor NT.sub.14, supplies the current flowing through the current mirror to the output stage side by a current mirror made of the pMOS transistors PT.sub.15 and PT.sub.16, and lastly a pMOS transistor PT.sub.19 is connected as a constant-current source between the supply line for the power supply voltage V.sub.DD and the node ND.sub.12, and makes the idling current I.sub.19 flow in the node ND.sub.12. Due to this, stabilization of DC operations during normal states and when shifting its states can be designed without considering the characteristics in the vicinity of the threshold voltage of pMOS transistor PT.sub.16, and thus stringent controls in the manufacturing process and the like are unnecessary.

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Kawaguchi, Japan

Tsuyoshi Chimura