CN101625575A - Complementary CMOS reference voltage source - Google Patents

Abstract

The invention discloses a complementary CMOS reference voltage source which belongs to the technical field of power sources and micro electrons. The CMOS reference voltage source comprises a reference current generating circuit, an NMOS transistor complementation generating circuit, a PMOS transistor complementation generating circuit and a proportion summing circuit, wherein the reference current generating circuit is used for generating reference current; the NMOS transistor complementation generating circuit is used for copying the reference current as drain current and generating a gate source voltage which varies inversely along with the temperature; the PMOS transistor complementation generating circuit is used for copying the reference current as drain current and generating a gate source voltage which varies directly along with the temperature; and the proportion summing circuit is used for proportionally summing the gate source voltage which varies directly along with the temperature and the gate source voltage which varies inversely along with the temperature and generating a voltage which does not vary along with the temperature. The reference voltage source structure which is realized by a pure CMOS process utilizes the temperature characteristics of different drain current regions of NMOS and PMOS transistors to proportionally sum the gate source voltage which varies directly and the gate source voltage which varies inversely so as to generate the reference voltage which does not vary along with the temperature.

Description

Complementary CMOS reference voltage source

Technical field

The present invention relates to power supply and microelectronics technology, particularly a kind of do not have a complementary CMOS reference voltage source that triple-pole type temperature characterisitic transistorized, that adopt NMOS and the transistorized different operating state of PMOS is carried out temperature compensation.

Background technology

In general, all there is certain fluctuation in the supply voltage of introducing from chip exterior, and high-precision mimic channel is higher to the stability requirement of bias voltage, therefore, in mimic channel, generally can use a reference voltage source, it can be converted into supply voltage the voltage with good voltage stability and temperature stability, for the other parts of circuit provide good reference voltage.

Reference voltage source typically refers to accurate, the stable voltage source of doing voltage reference in circuit.Along with the development of continuous increase, the especially system integration technology of integrated circuit scale, reference voltage source becomes on a large scale, indispensable basic circuit module in VLSI (very large scale integrated circuit) and the nearly all digital simulator system.

Reference voltage source is widely used in high-precision analog circuit and the Digital Analog Hybrid Circuits with the accuracy and the stability of its output reference voltage, for example precision comparator, high-precision A/D and D/A converter, linear voltage regulator, and DC/DC transducer.In A/D and D/A converter, data acquisition system (DAS) and various measuring equipment, all need high precision, high stability reference voltage source, and the precision of reference voltage source and stability have determined the whole system operation performance.

Traditional bandgap voltage reference owing to its preferably temperature stability be widely used in various Analogous Integrated Electronic Circuits and the Digital Analog Hybrid Circuits, but it requires technology can realize the triple-pole type transistor.Though can use parasitic triple-pole type transistor in the CMOS technology, also there are problems such as higher such as power consumption, that area is big, technology stability is high inadequately, therefore utilize pure CMOS technology to realize that high-precision voltage or current reference become needs.

Summary of the invention

In view of this, the object of the present invention is to provide a kind of complementary CMOS reference voltage source, the high-precision reference voltage source that provides pure CMOS technology to realize is provided.

For achieving the above object, the invention provides a kind of complementary CMOS reference voltage source, comprising:

Reference current generating circuit is used to produce reference current;

The compensation of NMOS pipe produces circuit, is used to duplicate described reference current as leakage current, produces the gate source voltage with the inversely proportional variation of temperature;

Pmos compensation produces circuit, is used to duplicate described reference current as leakage current, produces the gate source voltage with temperature variation in direct ratio;

The ratio summing circuit is used for the gate source voltage of described direct proportion variation and the gate source voltage of inverse proportion variation are carried out the ratio summation, produces not temperature variant voltage.

The reference voltage source structure that pure CMOS technology provided by the invention realizes, utilize the temperature characterisitic in the transistorized different leakage currents of NMOS and PMOS zone, the gate source voltage of direct proportion variation and the gate source voltage of inverse proportion variation are carried out the ratio summation, produce not temperature variant reference voltage.The present invention adopts Calibration Method that reference current is regulated, and has improved the temperature stability of output reference voltage; Do not need the triple-pole type transistor, reduced requirement effectively to technology, saved area and power consumption, in various CMOS integrated circuit (adjusting chip, data-switching chip), used easily, had very high practical value as reference voltage chip, electric energy computation chip, voltage.

Description of drawings

Fig. 1 is the circuit theory diagrams of complementary CMOS reference voltage source in the embodiment of the invention;

Fig. 2 is the circuit theory diagrams of a kind of reference current generating circuit in the embodiment of the invention;

Fig. 3 is the circuit theory diagrams of a kind of correcting current circuit in the embodiment of the invention.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, the present invention is described in further detail below in conjunction with accompanying drawing.

NMOS in the standard CMOS process works under state of saturation, and when leakage current was certain value, its gate source voltage was with the inversely proportional variation of temperature; And PMOS works under state of saturation, and when leakage current was defined as certain value, its gate source voltage was with temperature variation in direct ratio.Present embodiment carries out the ratio summation with the gate source voltage of direct proportion variation and the gate source voltage of inverse proportion variation, produces not temperature variant reference voltage; Simultaneously, adopt the method for correcting current to regulate electric current, improve the output voltage temperature stability.

Fig. 1 is the circuit theory diagrams of a kind of complementary CMOS reference voltage source of providing of present embodiment, and this reference voltage source comprises:

Reference current generating circuit is used to produce reference current;

The correcting current circuit is used for reference current is calibrated;

The compensation of NMOS pipe produces circuit, is used to duplicate described reference current as leakage current, produces the gate source voltage with the inversely proportional variation of temperature;

Pmos compensation produces circuit, is used to duplicate described reference current as leakage current, produces the gate source voltage with temperature variation in direct ratio;

The ratio summing circuit is used for the gate source voltage of described direct proportion variation and the gate source voltage of inverse proportion variation are carried out the ratio summation, produces not temperature variant voltage;

Output reference voltage produces circuit, is used for described not temperature variant voltage is exported as the reference voltage source.

In the structure of Fig. 1, at first produce reference current by reference current generating circuit; By reference current is duplicated, for the work NMOS pipe under the state of saturation provides leakage current, thereby the gate source voltage of NMOS pipe changes with the temperature inverse proportion; Equally reference current is duplicated, for the PMOS pipe of working under the state of saturation provides leakage current, thereby the gate source voltage of PMOS pipe changes with the temperature direct proportion; At the ratio summing circuit, the gate source voltage of direct proportion variation and the gate source voltage of negative ratio variation are carried out the ratio summation, produce not temperature variant voltage.The accuracy of the electric current that provides for NMOS pipe and PMOS pipe has directly determined the temperature stability of output voltage, and there is process deviation in the actual production, therefore adopt the method for correcting current that the value of reference current is regulated, thereby improve the temperature stability of output reference voltage.

When the NMOS pipe in the standard CMOS process is operated in the saturation region operation state, its gate source voltage such as formula (1):

$V_{\mathrm{gs}}=V_{\mathrm{th}}+\sqrt{\frac{{2I}_D}{{\mathrm{\μ}}_n{C}_{\mathrm{ox}}\frac{W}{L}}}---\left(1\right)$

μ wherein _nBe carrier mobility, I _DBe drain current, V _ThBe threshold voltage, C _OxBe grid oxygen electric capacity.

Ask first order derivative for formula (1) about temperature T, can get:

$\frac{{\∂V}_{\mathrm{gs}}}{\∂T}=\frac{{\∂V}_{\mathrm{th}}}{\∂T}-\frac{1}{2}\sqrt{\frac{{2I}_D}{C_{\mathrm{ox}}\frac{W}{L}}}*{{\mathrm{\μ}}_n}^{\frac{3}{2}}*\frac{{\∂\mathrm{\μ}}_n}{\∂T}---\left(2\right)$

In formula (2), threshold voltage V _ThWith carrier mobility μ _nWith temperature correlation, its remainder is temperature independent.

Common given threshold voltage V _ThWith the relational expression of temperature as shown in Equation (3):

V _th＝V _th(T ₀)+αVT(T-T ₀) (3)

T wherein ₀Be reference temperature, α VT is relevant with technology, and its value is generally a negative constant.Formula (3) is asked first order derivative to temperature, obtains formula (4):

$\frac{{\∂V}_{\mathrm{th}}}{\∂T}=\mathrm{\αVT}---\left(4\right)$

Carrier mobility μ _nRelation such as formula (5) with temperature:

${\mathrm{\μ}}_n\left(T\right)={\mathrm{\μ}}_n\left(T_0\right){\left(\frac{T}{T_0}\right)}^{\mathrm{\α\μ}}---\left(5\right)$

T wherein ₀Be reference temperature, α μ is relevant with technology, and its value is generally a negative constant.Formula (5) is asked first order derivative to temperature, obtains formula (6):

$\frac{{\∂\mathrm{\μ}}_n}{\∂T}=\frac{{\mathrm{\μ}}_n\left(T_0\right)\mathrm{\α\μ}}{T_0}{\left(\frac{T}{T_0}\right)}^{\mathrm{\α\μ}-1}---\left(6\right)$

With formula (4) and (6) substitution formula (2), can get:

$\frac{{\∂V}_{\mathrm{gs}}}{\∂T}=\mathrm{\αVT}-\frac{1}{2}\sqrt{\frac{{2I}_D}{C_{\mathrm{ox}}\frac{W}{L}}}*{\mathrm{\μ}}_n{\left(T_0\right)}^{-\frac{1}{2}}*\mathrm{\α\μ}*\frac{1}{{T_0}^{-\frac{1}{2}\mathrm{\α\μ}}}{T}^{-\frac{1}{2}\mathrm{\α\μ}-1}---\left(7\right)$

When α μ=-2, formula (7) abbreviation is:

$\frac{{\∂V}_{\mathrm{gs}}}{\∂T}=\mathrm{\αVT}+\sqrt{\frac{{2I}_D}{C_{\mathrm{ox}}\frac{W}{L}}}*{\mathrm{\μ}}_n{\left(T_0\right)}^{-\frac{1}{2}}*\frac{1}{T_0}---\left(8\right)$

Making formula (8) is zero, can obtain:

$I_{D1}=\frac{1}{2}{\left(\frac{-\mathrm{\αVT}*T_0}{{\mathrm{\μ}}_n{\left(T_0\right)}^{-\frac{1}{2}}}\right)}^2*C_{\mathrm{ox}}\frac{W}{L}---\left(9\right)$

When current value greater than I _D1The time, formula (8) shows that greater than zero gate source voltage changes with the temperature direct proportion; When current value less than I _D1The time, formula (8) shows that less than zero gate source voltage changes with the temperature inverse proportion.Wherein α μ is relevant with technology, and for the technology of reality, its value approaches-2, therefore can draw the relation of fast gate source voltage and temperature equally.

Though the above derivation of equation is based on nmos pass transistor, for the PMOS transistor, except its correlation parameter and nmos pass transistor have the difference, the basic derivation of equation is duplicate.Therefore in certain galvanic areas, gate source voltage changes with the temperature direct proportion; And in certain galvanic areas, gate source voltage changes with the temperature inverse proportion.

For the NMOS pipe of saturated provides the leakage current of certain value, make gate source voltage and temperature inversely proportional; For the PMOS pipe of saturated provides the leakage current of certain value, make gate source voltage and temperature in direct ratio.With these two kinds of voltage ratio summations, produce temperature independent output voltage then as reference voltage.

A kind of implementation of reference current generating circuit as shown in Figure 2, PMOS transistor M1 and nmos pass transistor M6 and M7 constitute start-up circuit, after circuit powered on, transistor M6 opened, and produces a pull-down current, make transistor M4 open, circuit is started working, and after the circuit working, transistor M7 opens, make that the gate voltage of transistor M6 is very low, thereby the M6 pipe is closed.Resistance R 0 and PMOS transistor M2 to M11, are to M5, nmos pass transistor M8 on the basis of traditional and biasing circuit supply independent, adopt cascode structure to constitute reference current generating circuit.Traditional and biasing circuit supply independent, two branch roads about having adopt left road current replication to right wing, right approach electric current are copied to left road again, thus the electric current that generation and power supply and temperature have nothing to do.Adopt the structure of cascade to improve the accuracy of current replication, thereby improved the precision of reference current, the electric current that finally flows through transistor M4 can be used as reference current.

A kind of implementation of correcting current circuit as shown in Figure 3, C0 is a control end to C5, when being low level, open the road electric current that it is controlled, B0 and B1 are connected PMOS pipe M4 in as shown in Figure 2 the reference current generating circuit and the grid of M5 respectively, six branch roads are respectively six road electric currents, this six road electric current can adopt the electric current that equates fully, also can adopt binary-coded method, the former degree of regulation height, but range of adjustment is little, and the latter is just in time opposite, can select according to the accuracy requirement of the reference voltage of reality.Equally, also be not limited to six the tunnel, can expand to more current branch, this circuit produces the electric current I through overregulating.When the needs high precision was regulated, six branch road weights were identical, are electric current I ₁, control signal C5-C0 is 000000 o'clock, six branch roads are all opened, thereby produce I=6I ₁, control signal C5-C0 is 111111 o'clock, six branch roads are all closed, thereby produce I=0, so control signal C5-C0 is 06-I from 000000111111 scope that can produce electric current I ₁, control interval is I ₁Output current.

The compensation of NMOS pipe produces a kind of implementation of circuit, can directly use the nmos pass transistor of grid source short circuit, its source end ground connection, the correcting current circuit produces electric current I n and sends into drain terminal, by emulation rational electric current I n is set, this moment, the grid voltage of NMOS pipe was voltage with the inversely proportional variation of temperature.

Pmos compensation produces the PMOS transistor that circuit is directly used grid source short circuit, its source termination power, the correcting current circuit produces electric current I p and sends into drain terminal, by emulation rational electric current I p is set, and this moment, the grid voltage of PMOS pipe was voltage with temperature variation in direct ratio.

The voltage summation method commonly used that can adopt the ratio summing circuit realizes getting final product, and summed result can directly be exported, and perhaps exports with voltage buffer according to actual needs.

The reference voltage source structure that the pure CMOS technology of the no triode that present embodiment provides realizes, can utilize the temperature characterisitic of the different operating state of NMOS pipe and PMOS pipe, effectively the variable quantity of positive temperature coefficient (PTC) and the variable quantity of negative temperature coefficient are offset, and then improve the temperature stability of output reference voltage; The reference voltage source structure that the pure CMOS technology of this no triode realizes can adopt Calibration Method that reference current is calibrated, and improves the precision of temperature compensation; And adopt standard CMOS process to realize, do not need parasitic triple-pole type transistor, reduced requirement effectively to technology, area and power consumption have been saved, in various CMOS integrated circuit (adjusting chip, data-switching chip), use easily, have very high practical value as reference voltage chip, electric energy computation chip, voltage.

In a word, the above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention.

Claims (7)

1. a complementary CMOS reference voltage source is characterized in that, comprising:

Reference current generating circuit is used to produce reference current;

The compensation of NMOS pipe produces circuit, is used to duplicate described reference current as leakage current, produces the gate source voltage with the inversely proportional variation of temperature;

Pmos compensation produces circuit, is used to duplicate described reference current as leakage current, produces the gate source voltage with temperature variation in direct ratio;

The ratio summing circuit is used for the gate source voltage of described direct proportion variation and the gate source voltage of inverse proportion variation are carried out the ratio summation, produces not temperature variant voltage.

2. complementary CMOS reference voltage source according to claim 1 is characterized in that, described CMOS reference voltage source also comprises:

The correcting current circuit is used for described reference current is calibrated.

3. complementary CMOS reference voltage source according to claim 2 is characterized in that, described CMOS reference voltage source also comprises:

Output reference voltage produces circuit, is used for described not temperature variant voltage is exported as the reference voltage source.

4. according to claim 1,2 or 3 described complementary CMOS reference voltage sources, it is characterized in that described reference current generating circuit adopts cascode structure to constitute.

5. according to claim 2 or 3 described complementary CMOS reference voltage sources, it is characterized in that, described correcting current circuit specifically comprises six branch roads, and the electric current of described six branch roads is equal fully, or adopts binary-coded mode that the electric current of described six branch roads is regulated.

6. according to claim 2 or 3 described complementary CMOS reference voltage sources, it is characterized in that the compensation of described NMOS pipe produces circuit and specifically comprises:

Adopt the nmos pass transistor of grid source short circuit, source end ground connection, described correcting current circuit produces the drain terminal that electric current is sent into described nmos pass transistor, and the grid voltage of described nmos pass transistor is the voltage with the inversely proportional variation of temperature.

7. according to claim 2 or 3 described complementary CMOS reference voltage sources, it is characterized in that described pmos compensation produces circuit and specifically comprises:

Adopt the PMOS transistor of grid source short circuit, the source termination power, described correcting current circuit produces electric current and sends into the transistorized drain terminal of described PMOS, and the transistorized grid voltage of described PMOS is the voltage with temperature variation in direct ratio.

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