Rail-to-Rail Operational Amplifier
A technology of operational amplifiers and MOS tubes, applied in amplifiers, differential amplifiers, DC-coupled DC amplifiers, etc., can solve the problems of low current replication accuracy, low current control degree, and large input stage transconductance changes in current mirror circuits.
Active Publication Date: 2018-03-30
FIFTH ELECTRONICS RES INST OF MINIST OF IND & INFORMATION TECH
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Problems solved by technology
However, in general, the working current of the complementary differential pair tubes is obtained by the mirror circuit, which has a low degree of control over the current. At the same time, the current replication accuracy of the current mirror circuit is low, which makes the transconductance of the input stage change greatly.
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[0013] refer to figure 1 , is a circuit structure diagram of an existing rail-to-rail input stage working in a subthreshold state. In the sub-threshold state, the transconductance of the MOS tube is proportional to its current. When the voltage of the input common-mode level signal goes up to the PMOS complementary differential pair tube to stop working, the current compensation circuit starts to work to maintain the total operating current of the input stage circuit. Unchanged, thereby reducing the transconductance fluctuation of the input stage circuit to be small. When the voltage of the input common-mode level signal goes down until the NMOS complementary differential pair tube stops working, its working principle is similar to the process of the voltage uplink of the common-mode level signal. In this input stage circuit, the copying accuracy of the current by the current mirror circuit is relatively low, especially for MOS transistors with narrow channel lengths. Due to ...
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The invention relates to a rail-to-rail operational amplifier, comprising a rail-to-rail input stage circuit, an up current compensating circuit, a down current compensating circuit, an output stage circuit and a current mirror circuit, wherein the rail-to-rail input stage circuit is connected with the up current compensating circuit, the down current compensating circuit, the current mirror circuit and the output stage circuit; the current mirror circuit is also connected with the up current compensating circuit, the down current compensating circuit and the output stage circuit; the current mirror circuit provides a bias current; the rail-to-rail input stage circuit accesses a common mode level signal and outputs the common mode level signal to the output stage circuit; the output stage circuit is used for processing the common mode level signal to output an amplified signal; the up current compensating circuit and the down current compensating circuit are respectively used for compensating the working current of the rail-to-rail input stage circuit when the voltage of the common mode level signal goes up or down, so that the working current of the rail-to-rail input stage circuit keeps constant and the transconductance fluctuation of the rail-to-rail input stage circuit of the rail-to-rail operational amplifier is small.
Description
technical field [0001] The invention relates to the field of circuit technology, in particular to a rail-to-rail operational amplifier. Background technique [0002] With the reduction of the feature size of the integrated circuit manufacturing process, the power supply voltage used by it gradually decreases, but the threshold voltage of the device does not decrease accordingly, so the common-mode input / output range of the operational amplifier is getting narrower and narrower, and it is difficult for a general operational amplifier to Meet the needs. [0003] Rail-to-rail operational amplifiers can achieve common-mode input and output ranges from high-supply high to low-ground, suitable for low-supply voltages. A rail-to-rail operational amplifier includes an input stage and an output stage. The traditional input stage circuit generally uses a complementary differential input pair composed of MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistor, MOS for short). To r...
Claims
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IPC IPC(8): H03F3/45
CPCH03F3/4521
Inventor 郝立超赖灿雄岳龙陈义强陈辉侯波郝明明路国光黄云恩云飞
Owner FIFTH ELECTRONICS RES INST OF MINIST OF IND & INFORMATION TECH