CN104484007B - A kind of current source for High Speed Analog and radio circuit - Google Patents

Abstract

A kind of current source for High Speed Analog and radio circuit of the present invention, comprises first via current generating circuit, the second road current generating circuit and electric current combiner circuit composition.First via current generating circuit output current I0 is the electric current increasing with temperature and increase; Second road current generating circuit output current I4 is the current source of temperature coefficient adjustable, and when lower than certain temperature threshold T0, the temperature coefficient of electric current I 4 is controlled by resistance R4; And when higher than T0, electric current I 4 is reduced to 0, temperature threshold T0 is controlled by resistance R3.The ultimate current I of the output of electric current combiner circuit _outbe added by electric current I 1 and electric current I 2 and obtain, electric current I 1 is k1 times of first via electric current I 0, and I2 is k2 times of the second tunnel electric current I 4.By the value of regulating resistance R3 and R4, and coefficient k 1 and k2 can obtain the output current of temperature coefficient controllable variable, can meet the different requirements of High Speed Analog and radio circuit current offset well.

Description

A kind of current source for High Speed Analog and radio circuit

Technical field

The invention belongs to possible current source circuit designs technical field, be specifically related to a kind of current source for High Speed Analog and radio circuit.

Background technology

Traditional current source mainly contains three classes, i.e. constant current source (electric current does not vary with temperature), positive temperature coefficient (PTC) current source and negative temperature parameter current source.The temperature coefficient change of these three kinds of current sources is single, and circuit design is subject to certain restrictions.Especially, in High Speed Analog and radio circuit application, the pre-frequency dividing circuit of such as high speed, its input/output signal amplitude range and operating frequency range are all subject to the impact of bias current very large.If use constant current source, circuit can be made normally to work at low-temperature zone electric current, but in high temperature section, along with the rising of temperature, device operating frequencies decline, and need larger electric current, obvious constant current source can not meet the demands; If use positive temperature coefficient (PTC) current source in this case, then during low temperature, electric current is by too small, and device is by cisco unity malfunction; In like manner, if use negative temperature parameter current source, then during high temperature electric current by too small.Visible, traditional current source is difficult to the designing requirement meeting high speed circuit completely.

Summary of the invention

The technical matters that the present invention solves is: overcome the deficiencies in the prior art, propose a kind of current source for High Speed Analog and radio circuit, make the temperature coefficient adjustable of electric current under low temperature, electric current can not be too small, maintain ptc characteristics under high temperature, High Speed Analog and radio circuit can be met under high/low temperature to the demand of current source simultaneously.

Technical scheme of the present invention is: a kind of current source for High Speed Analog and radio circuit, comprises first via current generating circuit, the second road current generating circuit and electric current combiner circuit;

Described first via current generating circuit comprises PMOS P1, PMOS P4, NPN pipe Q1 and resistance R1; Described second road current generating circuit comprises PMOS P7 ~ PMOS P12, NPN pipe Q3, NPN pipe Q4, resistance R3 and resistance R4; Described electric current combiner circuit comprises PMOS P2, PMOS P3, PMOS P5, PMOS P6, NPN pipe Q2 and resistance R2;

The source electrode of PMOS P1, PMOS P2, PMOS P3, PMOS P6, PMOS P7, PMOS P9 and PMOS P11 is all connected to power vd D; The drain electrode of PMOS P1 is connected to the source electrode of PMOS P4, the grid of PMOS P1 is connected to the grid of the drain electrode of PMOS P4 and PMOS P2, PMOS P7, PMOS P11 simultaneously, the drain electrode of PMOS P2 and PMOS P3 is all connected to the source electrode of PMOS P5, and the drain electrode of PMOS P5 outwards exports I as the output terminal of current source _out; After the grid of PMOS P4, PMOS P5, PMOS P6, PMOS P8, PMOS P10, PMOS P12 all links together, be together connected to the drain electrode of PMOS P6; The drain electrode of PMOS P7 is connected to the source electrode of PMOS P8, and the drain electrode of PMOS P9 is connected to the source electrode of PMOS P10, and the grid of PMOS P9 is connected to the grid of PMOS P3 and the drain electrode of PMOS P10 simultaneously, and the drain electrode of PMOS P11 is connected to the source electrode of PMOS P12; The collector of NPN pipe Q1 is connected to the drain electrode of PMOS P4, the emitter of NPN pipe Q1 is connected to one end of resistance R1, the base stage of NPN pipe Q1 and the base stage of NPN pipe Q2 are connected to external reference voltages VBG, the collector of NPN pipe Q2 connects the drain electrode of PMOS P6, one end of the emitter connecting resistance R2 of NPN pipe Q2, the equal ground connection GND of the other end of resistance R1 and resistance R2; The collector of NPN pipe Q3 is connected to the drain electrode of PMOS P10, the base stage of NPN pipe Q3 is connected to the collector of NPN pipe Q4 and the drain electrode of PMOS P12 simultaneously, the emitter of NPN pipe Q3 is connected to the base stage of NPN pipe Q4 and one end of resistance R4 simultaneously, other end one end of connecting resistance R3 and drain electrode, the other end of resistance R3 and the equal ground connection of emitter of NPN pipe Q4 of PMOS P8 simultaneously of resistance R4.

Resistance R1 ~ resistance R4 is constant temperature resistance or negative temperature coefficient resister, and resistance R3 and resistance R4 is variable resistor.

The present invention's advantage is compared with prior art:

1, the ultimate current I of electric current combiner circuit output _outbe added after being multiplied by scale-up factor k1, k2 by first via current generating circuit output current I0 and the second road current generating circuit output current I4 and obtain.Wherein, electric current I 0 is positive temperature coefficient (PTC) electric current; When lower than certain temperature threshold (T0), the temperature coefficient of electric current I 4 is controlled by resistance R4; And when higher than T0, electric current I 4 is reduced to 0, temperature threshold T0 is controlled by resistance R3.

2, current source circuit of the present invention is by regulating the value of variable resistor R3 and R4, and coefficient k 1 and k2, the output current of temperature coefficient controllable variable can be obtained, make the temperature coefficient adjustable of electric current under low temperature, electric current can not be too small, maintain ptc characteristics under high temperature, High Speed Analog and radio circuit can be met under high/low temperature to the different demands of current source simultaneously.

Accompanying drawing explanation

Fig. 1 is the structural representation of a kind of current source for High Speed Analog and radio circuit of the present invention;

Fig. 2 is that electric current I 0 and I4 synthesize output current I _outa kind of temperature characteristics schematic diagram;

Fig. 3 for a change resistance R4 changes I _outat the one emulation schematic diagram of-55 DEG C ~ T0 section current temperature coefficient;

Fig. 4 for a change resistance R3 changes I _outthe one emulation schematic diagram of temperature threshold T0.

Embodiment

A kind of current source for High Speed Analog and radio circuit that the present invention proposes, is described with reference to the accompanying drawings as follows.

If the electric current on PMOS P1, P2, P3, P7, P9, P11 is respectively I0, I1, I2, I3, I4, I5, current in proportion mirror then on PMOS P1, P2, P7, P11, on PMOS P2, electric current I1 is k1 times of electric current I0 on PMOS P1, and on PMOS P7, electric current I3 is k3 times of electric current I0 on PMOS P1.Current in proportion mirror on PMOS P3, P9, on PMOS P3, electric current I2 is k2 times of electric current I4 on PMOS P9, and wherein k1, k2, k3 are the positive number between 1 ~ 10.

Current source is made up of first via current generating circuit (100), the second road current generating circuit (200) and electric current combiner circuit (300) three part.The output current I of electric current combiner circuit (300) _outbe the final electric current exported, this electric current is added by electric current I2 on electric current I1 and PMOS P3 on PMOS P2 and obtains, and wherein electric current I 1 is k1 times of electric current I 0, and electric current I 2 is k2 times of electric current I 4, can obtain output current I _outexpression formula as follows.

I _out＝k1*I0+k2*I4(1)

The electric current (PTAT electric current) of electric current I 0 for increasing with temperature increase, by reference voltage V _bGproduced by NPN pipe Q1 and resistance R1.If the pressure reduction between the base stage of NPN pipe Q1 and emitter is V _bE1, then the expression formula of electric current I 0 is:

$I0=\frac{V_{\mathrm{BG}}-V_{\mathrm{BE}1}}{R1}---\left(2\right)$

Reference voltage V _bGfrom outside input, be temperature independent voltage, V _bE1for the voltage of negative temperature coefficient, set R1 as the resistance of stationary temperature coefficient here, so I0 is the electric current of positive temperature coefficient (PTC).In addition, be the resistance of negative temperature coefficient for R1, conclusions is applicable equally.

Same, by reference voltage V _bGproduce another group positive temperature coefficient (PTC) electric current by NPN pipe Q2 and resistance R2, this electric current is mirrored to P4, P5, P8, P10 and P12 by PMOS P6, to ensure that circuit normally works.

If the intersection point of NPN pipe Q3 emitter and Q4 base stage is A point, the intersection point of R4 one end and R3 one end is B point, if temperature threshold is T0.

As temperature T<T0, electric current flows to B point from A point, and the base current of Q4 can be ignored, and according to Kirchhoff's law, can calculate the expression formula of I4:

$I4=\frac{1}{R3+R4}*[V_{\mathrm{BE}4}-\frac{k3*R3}{R1}(V_{\mathrm{BG}}-V_{\mathrm{BE}1})](T<T0)---\left(3\right)$

As temperature T>T0, electric current flows to A point by B point, and now NPN pipe Q3 enters cut-off region, the base stage of current direction Q4 pipe.Because electric current I 4 is obtained by current mirror on PMOS P9, and the electric current on P9 equals the electric current on Q3, so electric current I 4 is 0.

If I4=0, show that the expression formula of resistance R3 is

$R3=\frac{R1}{k3}*\frac{V_{\mathrm{BE}4}}{V_{\mathrm{BG}}-V_{\mathrm{BE}1}}---\left(4\right)$

Well known, V _bEexpression formula be

$V_{\mathrm{BE}}=\frac{\mathrm{kT}}{q}\ln \frac{I_c}{I_s}---\left(5\right)$

Here can by V _bEregard the function with temperature correlation as, be V _bE(T), for a given temperature T0, can show that the expression formula of R3 is further

$R3=\frac{R1}{k3}*\frac{V_{\mathrm{BE}4}\left(T0\right)}{V_{\mathrm{BG}}-V_{\mathrm{BE}1}\left(T0\right)}---\left(6\right)$

T0 is temperature threshold, can need setting temperature T0 according to circuit, substitutes into the value that expression formula just can determine R3.

As temperature T<T0, if R1, R3, R4 are the resistance of stationary temperature coefficient, carrying out to I4 the temperature coefficient that differentiate can obtain I4 is

$\frac{\&PartialD;I4}{\&PartialD;T}=\frac{1}{(R3+R4)}*(\frac{{\&PartialD;V}_{\mathrm{BE}4}}{\&PartialD;T}+\frac{k3*R3}{R1}*\frac{{\&PartialD;V}_{\mathrm{BE}1}}{\&PartialD;T})---\left(7\right)$

Known V _bE1and V _bE4for the voltage of negative temperature coefficient, therefore V _bE1and V _bE4be negative to temperature T differentiate, show that I4 is also negative temperature coefficient voltage by above formula.When designing, R3 is determined by temperature threshold T0, and after R3 determines, the value changing R4 just can regulate the temperature coefficient of I4.When being the resistance of negative temperature coefficient for R1, R3, R4, conclusion roughly the same, is no longer derived herein.

Formula (2) and (3) are substituted into formula (1) can obtain

$I_{\mathrm{out}}=k2*\frac{1}{R3+R4}*V_{\mathrm{BE}4}+(\frac{k1}{R1}-k2*k3*\frac{R3}{R1*(R3+R4)})*(V_{\mathrm{BG}}-V_{\mathrm{BE}1})(T<T0)---\left(8\right)$

$I_{\mathrm{out}}=k1*\frac{V_{\mathrm{BG}}-V_{\mathrm{BE}1}}{R1}(T>T0)---\left(9\right)$

As can be seen here, as T<T0, Iout is the electric current of temperature coefficient controllable variable, and by regulating the value of variable resistor R3 and R4, and coefficient k 1 and k2 can change temperature coefficient; As T>T0, Iout is positive temperature coefficient (PTC) electric current.

Electric current I 0 and I4 synthesize output current I _outa kind of temperature characteristics as shown in Figure 2, wherein transverse axis is temperature, and unit is degree Celsius (DEG C), and temperature range is-55 ~ 125 DEG C, and the longitudinal axis is electric current, and unit is microampere (uA).This figure is made up of upper and lower two suite lines, above a suite line be respectively electric current I 0 and I4 variation with temperature figure, curve is below output current I _outvariation with temperature figure, can see that the temperature threshold in Fig. 2 situation is T0=50 DEG C,

Change resistance R4 and change output current I _outemulate schematic diagram as shown in Figure 3 in the one of-55 DEG C ~ T0 section current temperature coefficient, wherein transverse axis is temperature, and unit is degree Celsius (DEG C), and temperature range is-55 ~ 125 DEG C, and the longitudinal axis is electric current, and unit is microampere (uA).If resistance R3 is a fixed value, three output current I from top to bottom _outthe resistance value R4 that curve correspondence three is different, and I _outcurrent coefficient changes at-55 DEG C ~ T0, here temperature threshold T0=50 DEG C.

Change resistance R3 and change output current I _outtemperature threshold T0 mono-kind emulation schematic diagram as shown in Figure 4, wherein transverse axis is temperature, and unit is degree Celsius (DEG C), and temperature range is-55 ~ 125 DEG C, and the longitudinal axis is electric current, and unit is microampere (uA).If resistance R4 is a fixed value, three output current I from top to bottom _outthe resistance value R3 that curve correspondence three is different, and the temperature threshold T0 that correspondence three is different, be respectively 50 DEG C, 70 DEG C, 90 DEG C.

Above Fig. 2 to Fig. 4 three figure is the emulation schematic diagram of this circuit function, and the temperature threshold T0 of Fig. 2 and Fig. 3 can choose other value in-55 DEG C ~ 125 DEG C according to actual needs.

The content be not described in detail in instructions of the present invention belongs to the known technology of professional and technical personnel in the field.Although describe embodiments of the present invention by reference to the accompanying drawings, those of ordinary skill in the art can make various distortion or amendment within the scope of the appended claims.

Claims (2)

1., for a current source for High Speed Analog and radio circuit, it is characterized in that: comprise first via current generating circuit (100), the second road current generating circuit (200) and electric current combiner circuit (300);

Described first via current generating circuit (100) comprises PMOS P1, PMOS P4, NPN pipe Q1 and resistance R1; Described second road current generating circuit (200) comprises PMOS P7 ~ PMOS P12, NPN pipe Q3, NPN pipe Q4, resistance R3 and resistance R4; Described electric current combiner circuit (300) comprises PMOS P2, PMOS P3, PMOS P5, PMOS P6, NPN pipe Q2 and resistance R2;

The source electrode of PMOS P1, PMOS P2, PMOS P3, PMOS P6, PMOS P7, PMOS P9 and PMOS P11 is all connected to power vd D; The drain electrode of PMOS P1 is connected to the source electrode of PMOS P4, the grid of PMOS P1 is connected to the grid of the drain electrode of PMOS P4 and PMOS P2, PMOS P7, PMOS P11 simultaneously, the drain electrode of PMOS P2 and PMOS P3 is all connected to the source electrode of PMOS P5, and the drain electrode of PMOS P5 outwards exports I as the output terminal of current source _out; After the grid of PMOS P4, PMOS P5, PMOS P6, PMOS P8, PMOS P10, PMOS P12 all links together, be together connected to the drain electrode of PMOS P6; The drain electrode of PMOS P7 is connected to the source electrode of PMOS P8, and the drain electrode of PMOS P9 is connected to the source electrode of PMOS P10, and the grid of PMOS P9 is connected to the grid of PMOS P3 and the drain electrode of PMOS P10 simultaneously, and the drain electrode of PMOS P11 is connected to the source electrode of PMOS P12; The collector of NPN pipe Q1 is connected to the drain electrode of PMOS P4, and the emitter of NPN pipe Q1 is connected to one end of resistance R1, and the base stage of NPN pipe Q1 and the base stage of NPN pipe Q2 are connected to external reference voltages V _bG, the collector of NPN pipe Q2 connects the drain electrode of PMOS P6, one end of the emitter connecting resistance R2 of NPN pipe Q2, the equal ground connection GND of the other end of resistance R1 and resistance R2; The collector of NPN pipe Q3 is connected to the drain electrode of PMOS P10, the base stage of NPN pipe Q3 is connected to the collector of NPN pipe Q4 and the drain electrode of PMOS P12 simultaneously, the emitter of NPN pipe Q3 is connected to the base stage of NPN pipe Q4 and one end of resistance R4 simultaneously, other end one end of connecting resistance R3 and drain electrode, the other end of resistance R3 and the equal ground connection of emitter of NPN pipe Q4 of PMOS P8 simultaneously of resistance R4.

2. a kind of current source for High Speed Analog and radio circuit according to claim 1, it is characterized in that: resistance R1 ~ resistance R4 is constant temperature resistance or negative temperature coefficient resister, and resistance R3 and resistance R4 is variable resistor.