CN104133518A - Anti-interference current mirror image circuit - Google Patents

Abstract

The invention provides a current mirror image circuit capable of effectively restraining interference. A basic circuit comprises two transistors M1 and M2, a bias current source IIN and two low pass filters LPF1 and LPF2. The first low pass filter LPF1 comprises a first resistor R1 and a first capacitor C1, wherein the first resistor R1 is arranged between a grid electrode of the first transistor M1 and a grid electrode of the second transistor M2, and the first capacitor C1 is arranged between the grid electrode of the second transistor M2 and the first end of the second transistor. The second low pass filter LPF2 comprises a second resistor R2 and a second capacitor C2, wherein the second resistor R2 is arranged between the grid electrode of the first transistor M1 and the second end of the first transistor, and the second capacitor C2 is arranged between the grid electrode of the first transistor M1 and the first end of the first transistor. The current mirror image circuit can effectively filter noise out and is suitable for the field of integrated circuits with high accuracy requirements.

Description

A kind of jamproof current mirror circuit

Technical field

The invention belongs to integrated circuit fields, relate to a kind of mirror current source that disturbs inhibition filter function that has.

Background technology

Various mirror current sources are widely used in integrated circuit fields, basic current mirror circuit comprises a current mirror input transistors/field effect transistor M1, a current mirror output transistor/field effect transistor M2, each transistor comprises first end, the second end and gate terminal, the grid of M1 is connected with the grid of M2, and the first end of M1 is connected with power voltage terminal, and the second end is connected with gate terminal, the first end of M2 is connected with power voltage terminal, and the second end produces image current output signal.First end, the second end all can be configured to any one in source terminal and drain electrode end, and publication number is CN101375499A, and the patent document of CN101252131A has all disclosed similar current mirror circuit.

In the current mirror circuit of introducing at above-mentioned file, when input end comprises that noise is especially when high-frequency signal, noise can be transmitted to output terminal, cause the less desirable higher-order of oscillation, in the current mirror circuit described in Fig. 1, M1 is mirror image input metal-oxide-semiconductor, and M2 is mirror image output mos pipe, M1, the first end of M2 is configured to source terminal, and the second end is configured to drain electrode end, therefore M1, the source electrode of M2 is connected with voltage end, bias current sources I_iNbetween the drain electrode and earth terminal of M1, according to metal-oxide-semiconductor saturation region current formula:

$I_{\mathrm{DS}}=\frac{1}{2}K\frac{W}{L}{(V_{\mathrm{GS}}-V_{\mathrm{TH}})}^2---\left(1\right)$

Wherein, K=μ C_ox, μ is electron mobility, C_oxfor unit oxide layer electric capacity, W/L is raceway groove insulation course breadth length ratio, V_tHfor cut-in voltage.Due to two pipe balanced configurations, the cut-in voltage of M1 and M2 is equal, and therefore the size of output current is:

$I_{\mathrm{OUT}}=I_{\mathrm{IN}}\frac{W_2/L_2}{W_1/L_1}---\left(2\right)$

From formula (2), output current I_oUTwith input current I_iNbe the relevant mirror of multiple of raceway groove insulation course breadth length ratio.Traditional current mirror image source, because the impacts such as imperfect input, output resistance exist noise, affects the precision of output signal.In order to suppress noise, conventionally in Fig. 1, between side a and b, insert a low-pass filter LPF1, in Fig. 1, this wave filter is first-order filtering, the design of wave filter is not limited to the structure in figure, also can adopt multistage filtering according to actual conditions, the noise that A is ordered is through a large amount of decay after low-pass filter LPF1, and B point can obtain comparatively ideal signal, and ideal situation is V_b=V_a, then produce the image current output signal after denoising by M2.

$I_{\mathrm{DS}}=\frac{1}{2}\mathrm{KW}/L\·{(V_{\mathrm{GS}}-V_{\mathrm{TH}})}^2=\frac{1}{2}\mathrm{KW}/L\·(V_{\mathrm{GS}}^2-2V_{\mathrm{GS}}{V}_{\mathrm{TH}}+V_{\mathrm{TH}}^2)---\left(3\right)$

From formula (3), the source-drain current of metal-oxide-semiconductor and V_gSbecome nonlinear relationship, therefore can cause the ratio generation error of output current in upper figure and input current, this error size is relevant to noise.Therefore, the design of existing anti-interference filtration still can not be removed noise effectively, can not be applicable to the circuit design field that current noise and precision are had higher requirements.

Summary of the invention

Therefore,, in order further to improve the antijamming capability of current mirror circuit, the invention provides a kind of current mirror circuit with novel low-pass filter structure.Circuit has comprised two transistor M1, M2, bias current sources I_iNand two low-pass filter LPF1, LPF2, low-pass filter LPF2, LPF1 are between the grid of M1 and the grid of M2.The effectively filtering noise of circuit that the present invention proposes, is applicable to the higher integrated circuit (IC) design field of accuracy requirement.

Brief description of the drawings

Fig. 1 is existing anti-interference current mirror image circuit schematic diagram.

Fig. 2 is the New Anti-interference current mirror circuit that the present invention proposes.

Preferred forms

The preferred embodiments of the invention can be with reference to the mirror image circuit shown in figure 2, and basic circuit comprises first, second field effect transistor M1, the M2 of two pairings, bias current sources I_iNand first, second low-pass filter LPF1, LPF2, the source electrode of first, second field effect transistor M1, M2 is all connected with power voltage terminal, the drain electrode of the first field effect transistor M1 and bias current sources I_iNone end connect, bias current sources I_iNother end ground connection, second, the first low-pass filter LPF2, LPF1 is between the grid of the first field effect transistor M1 and the grid of the second field effect transistor M2, the first low-pass filter LPF1 comprises the first resistance R 1 and the first capacitor C 1, R1 is positioned at the first field effect transistor M1, between the grid of the second field effect transistor M2, one end of C1 is connected with the grid of M2, the other end is connected with power voltage terminal, the second low-pass filter LPF2 comprises the second resistance R 2 and the second capacitor C 2, R2 one end is connected with the grid of the first field effect transistor M1, the other end is connected with the drain electrode of the first field effect transistor M1, C2 one end is connected with the grid of the first field effect transistor M1, the other end is connected with power voltage terminal.

By two low-pass filter LPF1, LPF2 in circuit, the drain-source voltage noise that is positioned at the A end of the grid of the first field effect transistor M1 obtains effective filtering, further filter by LPF1 is made an uproar, be the B end in Fig. 2 at the grid of the second field effect transistor M2, can obtain a high precision output current signal that noise content is little.Filter resistance and electric capacity R1, C1, R2, the value of C2 can obtain by simulation calculation according to the designing requirement of circuit.

To the above-mentioned explanation of the disclosed embodiments, make professional and technical personnel in the field can realize or use scheme disclosed in this invention.To be apparent for those skilled in the art to the multiple amendment of embodiment, General Principle as defined herein can, in the situation that not departing from invention spirit or scope, realize in other embodiments.Therefore, the present invention can not be restricted to embodiment illustrated herein, but the widest scope consistent with principle features disclosed herein.

Claims (3)

1. a current mirror circuit, comprises the first transistor M1, transistor seconds M2, bias current sources I_iNand first, second low-pass filter LPF1, LPF2, the first end of first, second transistor M1, M2 is all connected with power voltage terminal, the second end of the first transistor M1 and bias current sources I_iNone end connect, bias current sources I_iNother end ground connection, the second, first low-pass filter LPF2, LPF1 are between the grid of the first transistor M1 and the grid of transistor seconds M2.

2. current mirror circuit as claimed in claim 1, described the first low-pass filter LPF1 comprises the first resistance R 1 and the first capacitor C 1, R1 is positioned at the first transistor M1, between the grid of transistor seconds M2, one end of the first capacitor C 1 is connected with the grid of transistor seconds M2, the other end is connected with the first end of transistor seconds M2, described the second low-pass filter LPF2 comprises the second resistance R 2 and the second capacitor C 2, second resistance R 2 one end are connected with the grid of the first transistor M1, the other end is connected with the second end of the first transistor M1, second capacitor C 2 one end are connected with the grid of the first transistor M1, the other end is connected with the first end of the first transistor M1.

3. current mirror circuit as claimed in claim 2, wherein the first end of first, second transistor M1, M2 is configured to source terminal, and the second end is configured to drain terminal.