Operational amplifier
A technology of operational amplifiers and amplifying circuits, applied in amplifiers, differential amplifiers, DC-coupled DC amplifiers, etc., can solve the problems of integrated circuit chip area influence, increase the size of differential transistors, etc., and achieve the reduction of size and layout area Effect
Inactive Publication Date: 2012-03-21
OKI ELECTRIC IND CO LTD
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[0004] However, if all the transistors in the operational amplifier are simply composed of high-voltage transistors, the threshold voltage (Vt) ratio accuracy of the high-voltage transistors is lower than that of low-voltage transistors, and the difference must be increased in order to improve the Vt ratio accuracy. Dimensions of moving transistors, etc.
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[0017] Hereinafter, embodiments of the operational amplifier of the present invention will be described in detail with reference to the drawings. refer to figure 1 , the operational amplifier 10 of the present invention is an operational amplifier including a differential amplifier circuit 12 arranged at an input stage and a current mirror circuit 14 connected to a subsequent stage of the differential amplifier circuit 12 .
[0018] In the primary differential amplifier circuit 12, a pair of N-channel MOS FETs (LV: Low Voltage) transistors (M1, M2) 24, 26 whose gates are respectively connected to the input terminals 20, 22 are provided. Drains of low withstand voltage transistors ( M1 , M2 ) 24 , 26 are connected to transistors ( M4 , M5 ) 28 , 30 which are N-channel high withstand voltage (HV) MOS FETs via connection points ( N1 , N2 ), respectively. The respective gates of the high withstand voltage transistors ( M4 , M5 ) 28 , 30 are connected together, and a bias potentia...
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An operational amplifier includes a differential amplifier circuit, receiving a low voltage signal, and a current mirror circuit provided on the downstream. The differential amplifier circuit also includes low withstand voltage N-channel transistors, connected to respective input terminals, and high withstand voltage N-channel transistors, connected to the drain electrodes of the low withstand voltage transistors via junction points, respectively. To the gate electrodes of both the high withstand voltage transistors supplied is a bias voltage. The source electrodes of the low withstand voltage transistors are connected to the drain electrode of another low withstand voltage transistor, which has its gate electrode supplied with a bias voltage so as to operate as a current source. Those low withstand voltage transistors are smaller in size than the high withstand voltage transistors.
Description
technical field [0001] The present invention relates to an operational amplifier of LSI (Large Scale Integrated Circuit) technology with high withstand voltage and low withstand voltage, in particular to an operational amplifier that is input with a low-voltage input signal and outputs a high-voltage output signal. Background technique [0002] Operational amplifiers requiring high voltage output are all composed of high voltage (HV: High Voltage) transistors. [0003] Patent Document 1: Japanese Patent Application Laid-Open No. 10-41752 [0004] However, if all the transistors in the operational amplifier are simply composed of high-voltage transistors, the threshold voltage (Vt) ratio accuracy of the high-voltage transistors is lower than that of low-voltage transistors, and the difference must be increased in order to improve the Vt ratio accuracy. Dimensions of moving transistors, etc. As a result, the chip area of the integrated circuit is greatly affected. Conten...
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IPC IPC(8): H03F3/45
CPCH03F3/3022H03F2203/45528H03F2203/45512H03F3/45475H03F3/45188H03F3/45192H03F3/45183H03F2203/45136H03F1/34H03F3/45H03F1/02
Inventor 樋口钢儿
Owner OKI ELECTRIC IND CO LTD