CN104518747A - Open-loop amplifier with accurately set gain - Google Patents
Open-loop amplifier with accurately set gain Download PDFInfo
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- CN104518747A CN104518747A CN201510027141.7A CN201510027141A CN104518747A CN 104518747 A CN104518747 A CN 104518747A CN 201510027141 A CN201510027141 A CN 201510027141A CN 104518747 A CN104518747 A CN 104518747A
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Abstract
An open-loop fully differential operational amplifier, of which the gain can be set precisely according to a resistance ratio, comprises differential input tubes P1 and P4, source feedback resistors R1 and R3 and a tail current Ib0, wherein P2 and Ib2 (as well as P5 and Ib4) form a gain raising circuit which is used for increasing the transconductance of cascade tubes P3 (and P6); NMOS tubes N1 and N2 form a local feedback loop which is used for forming a low-impedance path; R2 and R4 serve as source negative feedback resistors thereof and output resistors of the whole circuit. The signal gain of the open-loop amplifier is determined by the ratio of R2 to R1 (or R4 to R3). The traditional precise gain amplifier is mainly of the structure of a closed-loop operational amplifier, and the gain value of the traditional open-loop amplifier is usually not precise. The open-loop amplifier with the accurately set gain has the advantages of the traditional closed-loop operational amplifier and the traditional open-loop amplifier, and a precise gain value is obtained by adopting the design of the open-loop amplifier.
Description
Technical field
The present invention relates to the variable gain amplifier of extensive use in simulation and radio frequency integrated circuit, especially high-precision low-power consumption gain amplifier, adopted CMOS technology, in low-voltage and low-power dissipation Digital Analog Hybrid Circuits, there is larger advantage.Compared with traditional closed loop amplifier, there is structure simple, advantage low in energy consumption; There is the advantage that yield value can accurately be arranged compared with traditional Open-loop amplifier.Belong to integrated circuit (IC) design field.
Background technology
Along with the universal of mobile terminal product and popularization, the volume of electronic product constantly reduces, and lithium battery will become the main energy sources of product.Meanwhile, the theory of energy-conserving and environment-protective also more and more by society and industrial quarters accept, green energy conservation product will be subject to the welcome of client more.Therefore, in order to the flying power improving product reaches the object of energy-conserving and environment-protective simultaneously, the chip design of low-power consumption will be the trend of future development.The progress of integrated circuit processing technique has also agreed with this development trend, and along with the progress of technology, the size of device is more and more less, and supply power voltage is also more and more lower, and at present, it is even lower that the supply power voltage of main flow has dropped to 1.2V.
To digital circuit, the welfare that the progress of technique brings is, can reduce supply voltage, reduces the amplitude of oscillation, reduce parasitic capacitance, thus reduce power consumption; But for simulation and radio circuit, the progress of technique does not bring welfare to circuit design, is increased the pressure of circuit design on the contrary.For gain amplifier, this Pressure gauge is present, in order to obtain accurate gain, must use the operational amplifier possessing larger open-loop gain, along with the progress of technology, supply voltage is more and more lower, at lower voltages, in order to obtain larger open-loop gain, must adopt the operational amplifier of multilevel hierarchy, this significantly will increase power consumption; If want to reduce power consumption, just need to avoid using operational amplifier, and use the structure of open-loop gain amplifier, this significantly can reduce again the precision of gain.Circuit structure of the present invention is intended to solve the contradiction reducing power consumption and accurately arrange between gain.
Traditional precise gain amplifier as shown in Figure 1, OP is an open-loop gain is the Full differential operational amplifier of A0, resistance R1, R2, R3 and R4 constitute the feedback network of an anti-phase amplification, wherein the resistance value of R1 with R3 is identical, the resistance value of R2 with R4 is identical, and the yield value of so whole closed loop circuit is:
（1）
From formula (1), we can see, if want the accurate gain obtaining being determined by resistance value, i.e. R2/R1, just require that the open-loop gain A0 of OP is large as much as possible.This requirement result in amplifier must be designed to multilevel hierarchy, and OP is the amplifier of a fully differential, needs to design common mode feedback circuit, and this in fact adds complexity and the power consumption of circuit.
If do not adopt closed-loop structure, and adopt traditional open loop structure designing gain amplifier, will be as shown in Figure 2.This is the common source Open-loop amplifier of a band source negative feedback, and in traditional Open-loop amplifier, the gain of this structure is relatively accurate to.Wherein P1 and P2 is as amplifier tube, and its transconductance value is that the resistance value of gm, R1 and R3 is identical, and the resistance value of R2 with R4 is identical, and so the gain of circuit is:
（2）
From formula (2), we can see, the gain of this amplifier is relevant with the mutual conductance of metal-oxide-semiconductor P1 and P2, and mutual conductance can change along with the change of process corner and temperature, and the variation tendency of its variation tendency and resistance is without any relation, in brief, the yield value of this amplifier can not be given and accurately arrange.Certainly, also have way to allow its gain and mutual conductance have nothing to do, that is exactly increase this numerical value of gm*R1, and allow it be far longer than 1, thus make denominator approximate gm*R1, gain approximates R2/R1.Want to reach this object two ways nothing but, or increase gm, or increase R1, the former significantly can increase power consumption, and this just disagrees with the original intention reducing power consumption with employing Open-loop amplifier; The latter can make the gain of whole amplifier obviously reduce, because R1 is on the denominator of gain expressions, in fact, in actual applications, the resistance value of R1 and R3 is all smaller to circuit shown in Fig. 2.
Summary of the invention
The present invention is directed to the contradiction between gain accuracy and power consumption in conventional gain Amplifier Design, propose the open loop fully-differential amplifier that a kind of gain can accurately be arranged, its structure have employed open loop structure, avoid and use the circuit structure that brings of amplifier complicated and the problem that power consumption is higher, the problem that the gain simultaneously also solving traditional Open-loop amplifier can not accurately be arranged.That a kind of structure is simple, power consumption is lower, the accurate amplifier of gain.Concrete technical scheme is as follows:
The Open-loop amplifier that a kind of gain is accurately arranged by resistance ratio.Comprise Differential Input pipe P1 and P4, source feedback resistance R1 and R3, and tail current Ib0; P3 and P6 as the cascode level of P1 and P4 two input pipes, for improving output impedance.It is characterized in that: the grid of described Differential Input pipe P1, P4 is connected with input signal Vip, Vin respectively; Described source degeneration resistor R1, R3 are connected with the source electrode of input pipe P1, P4 respectively; Other one end of described two resistance R1, R3 is connected to one end of described tail current Ib0 jointly; The drain electrode of described input pipe P1, P4 is connected with cascode pipe P3, P6 respectively.
Circuit is lifted in described gain, is made up of P2 and Ib2 in the left-half of circuit, is made up of P5 and Ib4 at the right half part of circuit; The grid that input pipe P2 and P5 of circuit is lifted in described gain is connected respectively to the source electrode of described cascode pipe P3 and P6; What input pipe P2 and P5 of circuit was lifted in described gain misses the grid being connected respectively to described cascode pipe P3 and P6, and each via load current source Ib2 and Ib4 ground connection.
Described local feedback circuit, is made up of N1 pipe and its source degeneration resistor R2 in the left-half of circuit, is made up of N2 pipe and its source degeneration resistor R4 at the right half part of circuit; One end ground connection of described output resistance R2, in addition one end be connected to described NMOS tube N1 source electrode and as the Von output of whole circuit; One end ground connection of described output resistance R4, in addition one end be connected to described NMOS tube N2 source electrode and as the Vop output of whole circuit.
Advantage of the present invention and remarkable result:
1, adopt open-loop amplifier architectures, compared with closed-loop structure, can avoid using operational amplifier, thus significantly reduce complexity and the power consumption of circuit.
2, adopt the local negative feedback structure of NMOS tube and resistance composition, absorb most small-signal current, thus obtain accurate yield value under lower power consumption.
3, adopt gain to lift circuit to improve the mutual conductance of input stage cascode pipe, thus obtain larger impedance under lower power consumption.
Accompanying drawing explanation
Fig. 1 is the structure principle chart of traditional closed loop precise gain amplifier.
Fig. 2 is the structure principle chart of traditional open-loop gain amplifier.
Fig. 3 is the structure principle chart of the Open-loop amplifier that gain of the present invention can accurately be arranged.
Fig. 4 is the left side small-signal model figure of the Open-loop amplifier that gain of the present invention can accurately be arranged.
Fig. 5 is the enforcement structure of a kind of simplification of the Open-loop amplifier that gain of the present invention can accurately be arranged.
Fig. 6 is the enforcement structure that the single ended input of the Open-loop amplifier that gain of the present invention can accurately be arranged exports.
Embodiment
Below in conjunction with accompanying drawing, the invention will be further described.
The structure principle chart of the Open-loop amplifier that gain of the present invention can accurately be arranged as shown in Figure 3.As Open-loop amplifier, conventional open-loop fully-differential amplifier shown in it and Fig. 2 has similarity, they adopt PMOS (P1 and P2 of Fig. 2, or P1 and P4 of Fig. 3) as input pipe, and introduce at the source electrode of input pipe the equivalent transconductance that negative feedback resistor (R1 and R3) is used for changing input pipe.
Shown in Fig. 3 and Fig. 2 of the present invention, the difference of conventional open-loop amplifier is, at the source electrode of input pipe P1 and P4, except introducing negative feedback resistor R1 and R3, also have an other negative feedback path, that is exactly the low impedance path be made up of NMOS tube N1 and N2 and resistance R2 and R4; Other difference is that the load that the drain terminal of input pipe P1 with P4 is connected is completely different from conventional open-loop amplifier.
Because circuit is fully differential structure, the left and right sides is about center line specular, and therefore, we first illustrate the operation principle of side, the left side, and the operation principle of side, the right is identical with left side, can analogize.
For the circuit of side, the left side, we remove the feedback circuit of N1 and R2 composition, and the feedback circuit of P2 and Ib2 composition, only remaining R1, P1, P3 and Ib1, the major avenues of approach of these four device forming circuits, they together constitute the common-source stage amplifier of the band source resistance feedback of a cascode structure.Wherein Ib1 provides DC bias current, and in small-signal analysis, its impedance is much larger than the impedance of other device; P3 manages as cascode, and its effect is used to the small-signal output impedance improving input pipe P1, and so in this case, in the drain electrode (namely the grid of N1) of P3, the small signal impedance seen is:
（3）
In formula (3), gm3 and rds3 is transconductance value and the small-signal resistance value of P3 pipe respectively, gm1 and rds1 is transconductance value and the small-signal resistance value of P1 pipe respectively, and namely R1 is the resistance value of source feedback resistance R1 in Fig. 3.
Then, the basis of the major avenues of approach of circuit is introduced the feedback circuit be made up of P2 and Ib2.This is a single-stage common-source amplifier, its input connects the source electrode of P3 pipe, export the grid connecting P3 pipe, this just constitutes a typical gain and lifts (gain boost) circuit, it can improve gm2*rds2 doubly (wherein gm2 and rds2 is transconductance value and the small-signal resistance value of P2 pipe respectively) the transconductance value gm3 of cascode pipe, so in this case, in the drain electrode (namely the grid of N1) of P3, the small signal impedance seen is:
（4）
After specify that the small-signal resistance that the drain electrode of P3 is seen, we can set up small-signal model circuit to the circuit of side, the left side, as shown in Figure 4.
For the ease of analyzing, according to analysis above, these four devices of P2, P3, Ib2 and Ib1 can be equivalent to a resistance RO2, as shown in Figure 4, its resistance value is provided by formula (4).In addition, the rdsn1 in figure is the small-signal resistance value of N1 pipe.The value of two voltage-controlled current sources is as follows:
（5）
（6）
The gain that can calculate the circuit of small-signal model shown in Fig. 4 according to small-signal model and formula (5) and formula (6) is:
（7）
In the denominator of formula (7), the Section 2 of product term 1 adds a very complicated fraction, listed separately by this complicated fraction and decompose as follows:
（8）
According to the decomposition of formula (8), we can see, these three is all the number much smaller than 1, and maximum is last, and wherein the value of RO2 is determined by formula (4), in fact, this is the equal of the inverse of the product of four one-stage amplifier gains, under general technological level, also can be less than millesimal numerical value, therefore be negligible relative to 1, so we obtain gain be:
（9）
In fact, formula (9) can be understood by a kind of simple approximate analytical method, with reference to figure 4, according to formula (4), we know that the resistance value of RO2 is very large, so can think that the electric current of this path by RO2 flow direction ground is very little, negligible, namely the electric current of Ivccs1 can be ignored, and so can obtain V1=Vip according to formula (5), the current value so produced in R1 resistance is:
（10）
In formula (10), we suppose sense of current be according to Fig. 4 structure from top to bottom.So according to above analysis, ignore the electric current of vccs1 path, the electric current in R1 circuit flows to the path be made up of vccs2 and R2 completely, and in fact, this electric current flows through R2 resistance completely, thus produces a voltage Von on R2 resistance, and its expression formula is:
（11）
Simple conversion is carried out to formula (11) and just can obtain formula (9).
As previously mentioned, the operation principle of side, the right is identical with side, the left side, and the entire gain that so we just can obtain the Open-loop amplifier that gain of the present invention can accurately be arranged is:
（12）
According to formula (12), gain of the present invention accurately can arrange and show as, there are not other circuit parameters except resistance as shown in Equation (2) in gain expressions, the change of the yield value that the change that avoiding problems the performance of transistor causes, in traditional Open-loop amplifier, this problem exists always.
Gain of the present invention accurately can arrange and also show as, yield value is determined by the ratio of resistance R2 and R1, in integrated circuit design, although the absolute value of resistance can not be obtained accurately, but the ratio of resistance can accurately obtain, most of integrated circuit technology can both provide precision higher than millesimal resistance ratio.
Some unit of the present invention can be replaced by other structures, does not affect use of the present invention.Such as, gain of the present invention is lifted circuit and can be removed, and changes a fixing bias voltage into, and as shown in Figure 5, this is adapted at technology can provide higher single-stage gain amplifier or circuit application environment to the less demanding situation of gain accuracy.For another example, the present invention can be designed to the structure of single ended input Single-end output, as shown in Figure 6, as long as this structure quiescent point arranges rationally, and also can according to general principle work of the present invention.For another example, N pipe of the present invention and P pipe are exchanged, VDD-to-VSS line exchanges, and makes and is inputted by N tube grid, the structure that P pipe source electrode exports, also theory according to the invention and principle.
Claims (7)
1. the Open-loop amplifier that accurately arranges by resistance ratio of a gain.
2. comprise Differential Input pipe P1 and P4, source feedback resistance R1 and R3, and tail current Ib0; P3 and P6 as the cascode level of P1 and P4 two input pipes, for improving output impedance.
3. it is characterized in that: the grid of described Differential Input pipe P1, P4 is connected with input signal Vip, Vin respectively; Described source degeneration resistor R1, R3 are connected with the source electrode of input pipe P1, P4 respectively; Other one end of described two resistance R1, R3 is connected to one end of described tail current Ib0 jointly; The drain electrode of described input pipe P1, P4 is connected with cascode pipe P3, P6 respectively.
4. the gain according to claim 1 Open-loop amplifier that can accurately arrange.
5. it is characterized in that: circuit is lifted in described gain, be made up of P2 and Ib2 in the left-half of circuit, be made up of P5 and Ib4 at the right half part of circuit; The grid that input pipe P2 and P5 of circuit is lifted in described gain is connected respectively to the source electrode of described cascode pipe P3 and P6; What input pipe P2 and P5 of circuit was lifted in described gain misses the grid being connected respectively to described cascode pipe P3 and P6, and each via load current source Ib2 and Ib4 ground connection.
6. the gain according to claim 1 and 2 Open-loop amplifier that can accurately arrange.
7. it is characterized in that: described local feedback circuit, be made up of N1 pipe and its source degeneration resistor R2 in the left-half of circuit, be made up of N2 pipe and its source degeneration resistor R4 at the right half part of circuit; One end ground connection of described output resistance R2, in addition one end be connected to described NMOS tube N1 source electrode and as the Von output of whole circuit; One end ground connection of described output resistance R4, in addition one end be connected to described NMOS tube N2 source electrode and as the Vop output of whole circuit.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109073687A (en) * | 2015-07-08 | 2018-12-21 | 高通股份有限公司 | For by derived from the drain-source voltage of power gating device voltage apply compensated gain the device and method that measure load current |
| CN112653406A (en) * | 2020-11-27 | 2021-04-13 | 深圳供电局有限公司 | Biopotential amplifier and physiological signal measurement system |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101656516A (en) * | 2009-07-23 | 2010-02-24 | 复旦大学 | Full-difference CMOS ultra wide band low-noise amplifier |
-
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- 2015-01-20 CN CN201510027141.7A patent/CN104518747A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101656516A (en) * | 2009-07-23 | 2010-02-24 | 复旦大学 | Full-difference CMOS ultra wide band low-noise amplifier |
Non-Patent Citations (3)
| Title |
|---|
| J. J. F. RIJNS: "CMOS Low-Distortion High-Frequency Variable-Gain Amplifier", 《IEEE JOURNAL OF SOLID-ST/.TE CIRCUITS》 * |
| JAIME RAMÍREZ-ANGULO, ET.AL: "Low Voltage Gain Boosting Schemes for One Stage Operational Amplifiers", 《EUROPEAN CONFERENCE ON CIRCUIT THEORY & DESIGN》 * |
| 周唯晔: "宽增益动态范围CMOS可变增益放大器设计", 《中国优秀硕士学位论文全文数据库 信息科技辑》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109073687A (en) * | 2015-07-08 | 2018-12-21 | 高通股份有限公司 | For by derived from the drain-source voltage of power gating device voltage apply compensated gain the device and method that measure load current |
| CN112653406A (en) * | 2020-11-27 | 2021-04-13 | 深圳供电局有限公司 | Biopotential amplifier and physiological signal measurement system |
| CN112653406B (en) * | 2020-11-27 | 2023-03-03 | 深圳供电局有限公司 | Biopotential amplifier and physiological signal measurement system |
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Application publication date: 20150415 |