A current mirror circuit

Abstract

The invention discloses a current mirror circuit. By arranging a voltage replication circuit and an amplifying circuit in the current mirror circuit, the drain voltage of a current mirror source end subcircuit is amplified and compared with the drain voltage of a current mirror mirroring end subcircuit, the negative feedback mechanism of the amplifying circuit is utilized to ensure that the drain voltage of the current mirror source end subcircuit is equal to the drain voltage of the current mirror mirroring end subcircuit, so that the source voltages, grid voltages and drain voltages of the current mirror source end subcircuit and the current mirror mirroring end subcircuit are equal, consequently, the source-drain current flowing through the current mirror source end subcircuit is equal to the source-drain current flowing through the current mirror mirroring end subcircuit, and thereby the inaccuracy of the bias current of the current source mirror circuit, which is caused by the affection of the sizes of the elements composing the mirror circuit, is prevented.

Description

technical field [0001] The invention relates to a current mirror circuit. Background technique [0002] In IC design, in order to provide bias to the circuit, a current source mirror circuit is often used, see figure 1 and figure 2 ,in figure 1 Shown is a mirrored current source biased differential circuit, figure 2 Shown is a mirrored current source biased single-ended circuit. figure 1 and figure 2 The mirror circuit shown in part M 2 and M 1 See image 3 , theoretically flow through figure 1 and figure 2 M in 2 and M 1 The source-drain current should be proportional to n / m. But M 1 and M 2 The source-drain current I ds not only with the voltage between gate and source V gs is also related to the voltage between drain and source V ds Related, the details are as follows: [0003] I ds = 1 2 μ n C ox ...

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Problems solved by technology

[0004] Among them, μ n is the mobility constant of the MOS tube, C ox is the gate oxide capacitance constant of the MOS tube, W / L is the ratio of the width to the length of the MOS tube, λ=ΔL / L, V th It is the turn-on voltage. It can be seen from the above that the larger the L value of the MOS tube, the higher the V ds The smaller the influence, when the MOS tube can be ignored within a certain size range V ds to me ds influence, but with the progress of the process when the gate length of the MOS tube enters the nanometer level, the V ds to me ds The influence of can not be ignored, at this time due to V ds to me ds impact, will lead to Figure 1-Figure 3 The current mirror circuit shown in the M 2 and M 1 The ratio of source to drain current is not n / m, which results in Figure 1-Figure 3 inaccurate bias current for the current source mirror circuit shown in the

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