CN102790594B - Dual-mode automatic gain control circuit working at ultra-low supply voltage - Google Patents
Dual-mode automatic gain control circuit working at ultra-low supply voltage Download PDFInfo
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- CN102790594B CN102790594B CN201110129392.8A CN201110129392A CN102790594B CN 102790594 B CN102790594 B CN 102790594B CN 201110129392 A CN201110129392 A CN 201110129392A CN 102790594 B CN102790594 B CN 102790594B
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Abstract
The invention discloses a dual-mode automatic gain control circuit working at an ultra-low supply voltage. The dual-mode automatic gain control circuit relates to an integrated circuit and comprises a programmable transconductance operational amplifier, an envelope detection circuit, a gain control circuit, an isolation capacitor, an input resistor, a resistor array, an MOS (Metal Oxide Semiconductor) tube equivalent resistor, a comparator and a selector switch. The envelope detection circuit detects a comparison result between an output signal and an inflexion point threshold voltage to decide a working state of the circuit; in an incompressible working state, the selector switch selects a resistance array as a feedback circuit, amplifies a voltage signal at a microphone output end and decreases a degree of distortion of the circuit; in a compressible working state, the dual-mode automatic gain control circuit starts the MOS tube equivalent resistor as the feedback circuit to achieve an automatic gain control of the operational amplifier. The envelope detection circuit achieves different starting time and recovery time, and the gain control circuit achieves an effective utilization of power consumption when sound volumes are in different levels. The dual-mode automatic gain control circuit is used for a hearing aid, a high-precision work and high efficiency for controlling the power consumption of the circuit can be achieved under the ultra-low supply voltage.
Description
Technical field
The present invention relates to digital deaf-aid microphone and read integrated circuit, and relate to the high-precision reading integrated circuit being applicable to hearing aids micro-acoustic-electric system (MEMS) microphone sensor in more detail.
Background technology
Along with the continuous progress of micro-acoustic-electric system (MEMS) technology, micro-acoustic-electric hearing aid microphone transducer arises at the historic moment, it has that volume is little, low in energy consumption, distortion is little and the advantage such as noise resisting ability is strong, and the reading circuit corresponding to it becomes the focus of industrial quarters research.
This transducer can be equivalent to an ideal voltage source usually: a very little resistance on desired voltage subject string.But the signal that microphone micro-electro-mechanical sensors exports is very faint, and generally only between μ V ~ mV magnitude, this proposes very harsh requirement to the design of reading circuit.The noise level of reading circuit and precision determine its minimum signal amplitude that can detect, so low noise and high-precision reading circuit are designed to have high-precision key to realize reading circuit, especially under digital deaf-aid needs low-down supply voltage situation.
The simulation Design of Automatic Gain Control of microphone reading circuit mainly can be divided into analog feedback to control amplifier forward direction open-loop gain in the world at present, namely analog feedback controls the (reference: Jones of amplifier bias current, Mario Martinez: " a kind of CMOS hearing aids ", analog integrated circuit and signal transacting, 21,163-172 (1999); Bake: ' a kind of low-power consumption monocycle for artificial ear and dicyclo automatic growth control ', solid-state circuit, SC-41 (9), pp.1983-1996,2006) and analog feedback control the gate source voltage (reference: Huo Man: " a kind of low noise CMOS automatic gain control ", solid-state circuit, SC-27 (7) of controlled metal-oxide-semiconductor equivalent resistance, pp.974-981,1992; Jin Shuyong: " a kind of efficient analog front end circuit of sub-1V digital deaf-aid ", solid-state circuit, SC-41 (4), pp.876-882,2006.) and current-mode FEEDBACK CONTROL metal-oxide-semiconductor mutual conductance (reference: lattice draw Leix: " low pressure subthreshold value index amplifies and automatic growth control ", circuit, device and system, Vol.152, No.1, Feb 2005) two schemes.And above automatic gain control circuit is applied widely in the acquisition of simulation field of hearing aids.But the former shortcoming is that its linearity can be subject to the restriction of technique and supply voltage, especially when supply voltage is lower.The advantage of analog feedback is that its signal has stronger continuity.But the difficult point of analog feedback is the realization of the amplifier output accuracy of low-voltage.The multiplication factor of usual amplifier has realized comparatively ideal precision under the control of analog feedback, and to realize very high precision be in integrated circuits extremely difficult, usually needs complicated compensating circuit or very large power consumption.Current-mode feedback system
[5]shortcoming be that amplifier itself does not have negative feedback structure, thus the precision of system to signal transacting is lower.And digital deaf-aid requires that reading circuit has extraordinary reading accuracy, this proposes challenge to the design of reading circuit.
Summary of the invention
The object of the invention is to provide one and work in pole low supply voltage dual mode automatic gain control circuit, may be used for the bimodulus automatic growth control reading circuit of digital deaf-aid, it is on the basis by controlled metal-oxide-semiconductor equivalent resistance ride gain, replace metal-oxide-semiconductor equivalent resistance by electric resistance array in the on-compressed state, effectively solve the problem of precision under its non-compressed state; Effectively solve the problem that power consumption under compressive state is higher simultaneously.
For achieving the above object, technical solution of the present invention is:
One works in pole low supply voltage dual mode automatic gain control circuit, for the 1V working power voltage of hearing aids, comprising:
Programmable trans-conductance amplifier, for the amplification outputed signal microphone MEMS;
Two capacitance resistance wares in parallel form the high-pass filtering to input signal, the input of the capacitance resistance ware be wherein made up of with the second isolation capacitance the second input resistance is connected with a positive input terminal of programmable trans-conductance amplifier differential input end, and output is connected with microphone output; The input of another capacitance resistance ware be made up of with the first isolation capacitance the first input resistance is connected with the negative input end of programmable trans-conductance amplifier differential input end, and output is connected to the ground;
By the first electric resistance array that the output of programmable trans-conductance amplifier is connected with the negative input end of programmable trans-conductance amplifier, and by the second electric resistance array that the output of programmable trans-conductance amplifier is connected with the positive input terminal of programmable trans-conductance amplifier, for programmable trans-conductance amplifier under uncompressed operating state to the amplification of signal;
The metal-oxide-semiconductor equivalent resistance array element that programmable trans-conductance amplifier output is connected with input, for the automatic growth control under compressive state;
The selector switch be connected with metal-oxide-semiconductor equivalent resistance unit with electric resistance array unit;
Gain control circuit, for generation of the voltage of automatic growth control; The input of this gain control circuit connects envelope detected circuit output end, and output connects the grid of metal-oxide-semiconductor equivalent resistance array;
Envelope detected circuit, obtains detecting the energy of programmable trans-conductance amplifier output signal in order to carry out rectification and filtering to signal; The input of this envelope detected circuit connects programmable trans-conductance amplifier output, and output connects the input of gain control unit;
Wherein, described gain control circuit, the adaptation function of power consumption is realized by two two-level concatenation amplifier negative feedback loops, wherein form a secondary feedback loop by the first embedded amplifier amp1 and the first NMOS tube M1, the second embedded amplifier amp2 and the second PMOS M2 forms another secondary feedback loop; The electric current of mirror image first NMOS tube M1 and the second PMOS M2 is in the 4th PMOS M4, and put the 4th PMOS M4 in sub-threshold region to provide a control voltage being applicable to control metal-oxide-semiconductor equivalent resistance unit, thus realize the reduction of the distortion factor under automatic growth control state under 1V supply voltage.
In such scheme, described envelope detected circuit, adopts filter cascade form: form front-end filtering circuitry by the first PMOS M1 in envelope detected circuit, the second PMOS M2 and electric capacity C, it has rectification function concurrently; 4th PMOS M4, the 5th PMOS M5, the 6th PMOS M6 and electric capacity C1 form rear end filter circuit, and the first PMOS M1, the second PMOS M2, the 6th PMOS M6 work in sub-threshold region.
Circuit of the present invention is applicable to very low operation supply voltage (e.g., below 1V), for portable digital hearing aids provides a kind of low-voltage, and low-power consumption and high-precision reading circuit.
Meanwhile, invent the gain control circuit with power consumption adaptation function accordingly, realize volume when raising gradually, the reduction gradually of its circuit system power consumption.Above circuit, at below supply voltage 1V, still can normally work.The present invention proposes the method achieving automatic ride gain high accuracy and power consumption rate detection signal under uncompressed operating state and the circuit module worked at lower voltages accordingly.
Accompanying drawing explanation
Fig. 1 is that one of the present invention works in pole low supply voltage dual mode automatic gain control circuit schematic diagram.
In figure, main element illustrates:
Programmable trans-conductance amplifier 1 first isolation capacitance 2
Second isolation capacitance 3 first input resistance 4
Second input resistance 5 first electric resistance array 6
Second electric resistance array 7 selector switch 8
Metal-oxide-semiconductor equivalent resistance 9 envelope detected circuit 10
Comparator 11 is beneficial control circuit 12 once
Fig. 2 of the present inventionly a kind ofly works in the envelope detected circuit working in more than 1V supply voltage in the low supply voltage dual mode automatic gain control circuit of pole;
Fig. 3 of the present inventionly a kind ofly works in the gain control circuit working in more than 1V supply voltage in the low supply voltage dual mode automatic gain control circuit of pole.
Embodiment
The present invention gives one and work in pole low supply voltage dual mode automatic gain control circuit, for the 1V working power voltage of hearing aids; It comprises:
Programmable trans-conductance amplifier, for the amplification outputed signal microphone MEMS;
Two electric capacity that programmable trans-conductance amplifier two inputs are connected with ground with microphone output are respectively connected with resistance device, form the high-pass filtering to input signal;
Two electric resistance array unit that programmable trans-conductance amplifier output is connected with input, for programmable trans-conductance amplifier under being formed in uncompressed operating state to the amplification of signal;
The metal-oxide-semiconductor equivalent resistance array element that programmable trans-conductance amplifier output is connected with input, for the automatic growth control under compressive state;
The selector switch be connected with metal-oxide-semiconductor equivalent resistance unit with electric resistance array unit;
Input is connected the gain control circuit of envelope detected circuit output end and metal-oxide-semiconductor equivalent resistance Array gate with output, for generation of the voltage of automatic growth control;
Input is connected the envelope detected circuit of programmable trans-conductance amplifier output and gain control unit input with output, obtain detecting the energy of programmable trans-conductance amplifier output signal in order to carry out rectification and filtering to signal.
Wherein envelope detected circuit, can realize different start-up times and recovery time, makes automatic gain control circuit adapt to the physiological requirements of people's ear to the response of voice signal.
Dual mode automatic gain control circuit of the present invention is under the condition increased gradually in volume, the gain control circuit that the power consumption of realization own reduces; There is provided one to be applicable to control metal-oxide-semiconductor grid, two that are in high potential export control voltage, to realize the reduction of the distortion factor under automatic growth control state under 1V supply voltage simultaneously.
A kind of microphone dual mode automatic gain control circuit, efficiently solves power consumption of the prior art and nonlinear problem by adopting the mode of power consumption rate circuit module and the electric resistance array replacement metal-oxide-semiconductor equivalent resistance working in low supply voltage.
The present invention is by first, and two isolation capacitances and resistance device 2 ~ 5 pairs of microphone direct current signals carry out high pass, and filtering microphone direct current signal, reads microphone small-signal by programmable trans-conductance discharge circuit 1; Comparator 11 compares envelope signal and the reference flex point threshold voltage of envelope detected circuit 10 output, choosing of its comparative result determination selector switch 6.When the envelope signal that envelope detected circuit 10 detects programmable trans-conductance amplifier 1 output signal is less than with reference to flex point threshold voltage, circuit system works in uncompressed operating state, and selector switch 6 selects first, two input resistance devices 4,5 and first, two electric resistance arrays 6,7 as feedback loop.When the envelope signal that envelope detected circuit 10 detects programmable trans-conductance amplifier 1 output signal is greater than with reference to flex point threshold voltage, circuit system works in compressive state, and selector switch 6 selects metal-oxide-semiconductor equivalent resistance 9 as feedback loop; Simultaneously gain control circuit 12 pairs of envelope signals carry out process and obtain gain control signal, and the grid voltage of this gain control signal to metal-oxide-semiconductor equivalent resistance 9 controls.
This circuit owing to adopting first under uncompressed operating state, two input resistances 4,5 and first, two electric resistance arrays 6,7 replace the mode of metal-oxide-semiconductor equivalent resistances 9 to achieve low supply voltage under high-precision wheat can wind number read, simultaneously by analog feedback, the mode controlling metal-oxide-semiconductor equivalent resistance 9 grid achieves the automatic growth control under low supply voltage.
Fig. 1 describes exemplary according to dual mode automatic gain control circuit of the invention process.Dual mode automatic gain control circuit is divided into following components, comprise: programmable trans-conductance amplifier (1), by programmable trans-conductance amplifier (1) first and second input respectively with microphone output and the first and second electric capacity of being connected of ground and input resistance device (2 ~ 5), be connected across first electric resistance array (6) of programmable trans-conductance amplifier (1) first input end and the second output, be connected across second electric resistance array (7) of programmable trans-conductance amplifier (1) second input and the first output, be connected across the metal-oxide-semiconductor equivalent resistance (9) of programmable trans-conductance amplifier (1) input and output, be connected across first, the selector switch (6) of two electric resistance array unit (4) and metal-oxide-semiconductor equivalent resistance (9), output and input are connected the envelope detected circuit (10) of gain control circuit (12) input and programmable trans-conductance amplifier (1) output respectively, connect the gain control circuit (12) of envelope detected circuit (10) output and metal-oxide-semiconductor equivalent resistance (9) grid, be connected to the comparator (11) between envelope detected circuit (10) output and selector switch (6).
In actual applications, under considering lower supply voltage and lower power consumption, the output signal of programmable trans-conductance amplifier carries out envelope detected (with reference to accompanying drawing 2) by envelope detected circuit to it.Consider that this envelope detected circuit working is in low supply voltage state, this envelope detected circuit adopts filter cascade form, and 1,2,6MOS pipe works in sub-threshold region 13.Managed by 1,2MOS and form front-end filtering circuitry with electric capacity C, it has rectification function concurrently; 4,5,6MOS pipe forms rear end filter circuit with electric capacity C1.Owing to designing the cut-off frequency of front-end filtering circuitry much smaller than rear end filter circuit.Filter is when large-signal inputs, and this filter time constant (compression time) is:
Subsequently, when large-signal input becomes small-signal input, 4,5,6MOS pipe turns off, then determine that this filter time constant (recovery time) is by rear end filter circuit:
From above-mentioned theory, envelope detected circuit can realize different startups and recovery time. and circuit has following functions simultaneously: when namely input signal is larger, output voltage V
outthen less.
When circuit system is under the uncompressed operating state with compressing of volume, the output signal of envelope detected circuit is undertaken processing (with reference to accompanying drawing 3) by gain control circuit.The output signal V of envelope detected circuit
pDor compression knee voltage V
tHthe input signal of gain control circuit for this reason, V
1and V
2for the control signal exported, V
cit is Exponential gain control adjustment end.
Amplifier amp1,2 and pipe M1,2 compositions, two negative feedback loops, because resistance R1 and R2 is equal, make pipe M1 like this, M2 and M5, the source-drain voltage of M6 is accurately equal, the mirror image precision of motor current, thus increases substantially the input resistance of gain control circuit, therefore, the output voltage V of envelope detected circuit
pDor knee voltage V
tHcan directly be added to the input of gain control circuit and can not decay be produced.
The equivalent inpnt resistance of efficient gain control circuit is:
R
in＝A*[r
5//(R
1+r
1)]
Wherein A is the negative feedback loop open-loop gain that amplifier amp1 and pipe M1 form, and r1,5 is M1, the drain impedance of 5.
When uncompressed operating state, envelope voltage signal V
pDvalue is greater than knee voltage V
tH, now V
tHdirectly be added to the input of gain control circuit.The electric current that M1, M2 flow through is:
The node voltage between R3 and R4 is made to remain Vc, because R3 and R4 is equal, so two output voltage values are respectively by the feedback loop of amp3 and M4. composition
V
1，2＝V
C±V
X
Due to R3,4, and R1,2, equal, therefore the differential mode voltage of control circuit exports and is
V
X＝I
control·R
3＝V
TH-V
LH
When compression work state, envelope voltage signal V
pDbe less than knee voltage signal V
tH, now envelope voltage signal can substitute the output V that input that knee voltage signal is added to gain control circuit makes control circuit
1and V
2differential mode voltage V
xreduce, thus reduce the gain of variable gain amplifier.Now M1,2, the quiescent current of 3 is such as formula shown in (7), reduce to some extent than the operating current (as formula (4)) under non-compressed state, along with the increase of input signal amplitude, the electric current of efficient gain control circuit will reduce further, and when volume reaches maximum, the power consumption that gain control circuit consumes about is reduced to 1/10th under uncompressed operating state.
Because the signal bandwidth of gain control circuit process is close to DC level, amp1, the value of the bias current of 2,3 can meet bandwidth demand at about 100nA.And consider the stability problem of power consumption and feedback control loop, I
controldesign load be 3.5 μ A.
In order to reduce the non-linear of metal-oxide-semiconductor equivalent resistance, two output voltage V1 of gain control circuit, 2 need as far as possible near supply voltage, therefore pipe M4 is placed in sub-threshold region to keep enough large mutual conductance, thus the feedback loop that amp3 and M4. is formed obtain enough loop gains.On the other hand, in order to the impact preventing MRC resistance to be subject to power supply noise, Vdd produced by LDO power management module in sheet, ensures that systematic distortion degree is in enough little scope further.
In circuit stability, the secondary amplifier closed loop stability of gain control circuit is arranged by the bias current of 1,2,3amp, and miller capacitance C and resistance r keeps. and bias current need be set as:
I
control, worstcaseit is the minimum current value of 1,2,3,4,5,6MOS pipe source and drain.
1,2,5,6MOS pipe and amp1,2 another loops of composition, carry out zero compensation by electric capacity C1 to it, after compensating, its dominant pole is
Wherein g
m-amp1for the mutual conductance of amp1, and
Wherein g
m, r
o2be respectively mutual conductance and the output resistance of 2MOS pipe.
Be more than the description of execution mode inventive microphone being worked in 1V supply voltage dual mode automatic gain control circuit, to one skilled in the art, some advantage having obtained this circuit is apparent.Also should be appreciated that and can carry out various change, amendment and alternative embodiment in scope and spirit of the present invention, be all included in the scope of claims of the present invention protection.
Claims (2)
1. work in a pole low supply voltage dual mode automatic gain control circuit, for the 1V working power voltage of hearing aids; It is characterized in that, comprising:
Programmable trans-conductance amplifier, for the amplification outputed signal microphone MEMS;
Two capacitance resistance wares in parallel form the high-pass filtering to input signal, the input of the capacitance resistance ware be wherein made up of with the second isolation capacitance the second input resistance is connected with a positive input terminal of programmable trans-conductance amplifier differential input end, and output is connected with microphone output; The input of another capacitance resistance ware be made up of with the first isolation capacitance the first input resistance is connected with the negative input end of programmable trans-conductance amplifier differential input end, and output is connected to the ground;
By the first electric resistance array that the output of programmable trans-conductance amplifier is connected with the negative input end of programmable trans-conductance amplifier, and by the second electric resistance array that the output of programmable trans-conductance amplifier is connected with the positive input terminal of programmable trans-conductance amplifier, for programmable trans-conductance amplifier under uncompressed operating state to the amplification of signal;
The metal-oxide-semiconductor equivalent resistance array element that programmable trans-conductance amplifier output is connected with input, for the automatic growth control under compressive state;
The selector switch be connected with metal-oxide-semiconductor equivalent resistance unit with electric resistance array unit;
Gain control circuit, for generation of the voltage of automatic growth control; The input of this gain control circuit connects envelope detected circuit output end, and output connects the grid of metal-oxide-semiconductor equivalent resistance array;
Envelope detected circuit, obtains detecting the energy of programmable trans-conductance amplifier output signal in order to carry out rectification and filtering to signal; The input of this envelope detected circuit connects programmable trans-conductance amplifier output, and output connects the input of gain control unit;
Wherein, described gain control circuit, the adaptation function of power consumption is realized by two two-level concatenation amplifier negative feedback loops, wherein form a secondary feedback loop by the first embedded amplifier amp1 and the first NMOS tube M1, the second embedded amplifier amp2 and the second PMOS M2 forms another secondary feedback loop; The electric current of mirror image first NMOS tube M1 and the second PMOS M2 is in the 4th PMOS M4, and put the 4th PMOS M4 in sub-threshold region to provide a control voltage being applicable to control metal-oxide-semiconductor equivalent resistance unit, thus realize the reduction of the distortion factor under automatic growth control state under 1V supply voltage.
2. dual mode automatic gain control circuit according to claim 1, it is characterized in that, described envelope detected circuit, adopts filter cascade form: form front-end filtering circuitry by the first PMOS M1 in envelope detected circuit, the second PMOS M2 and electric capacity C, it has rectification function concurrently; 4th PMOS M4, the 5th PMOS M5, the 6th PMOS M6 and electric capacity C1 form rear end filter circuit, and the first PMOS M1, the second PMOS M2, the 6th PMOS M6 work in sub-threshold region.
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| CN201110129392.8A CN102790594B (en) | 2011-05-18 | 2011-05-18 | Dual-mode automatic gain control circuit working at ultra-low supply voltage |
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| CN103050119B (en) * | 2012-12-30 | 2015-06-17 | 安徽科大讯飞信息科技股份有限公司 | Self-adaptive detection method for synchronism of lamplight/motor and sound |
| CN104183241B (en) * | 2013-05-28 | 2017-09-29 | 无锡华润矽科微电子有限公司 | Improve the control circuit and method of audio signal volume regulation |
| CN105305990B (en) * | 2015-12-09 | 2018-02-09 | 北京中科汉天下电子技术有限公司 | A kind of power control circuit of power amplifier |
| CN112968684B (en) * | 2021-02-08 | 2024-04-05 | 西安理工大学 | Broadband programmable gain amplifier based on transconductance switching technology |
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| CN101102097A (en) * | 2006-07-07 | 2008-01-09 | 美国凹凸微系有限公司 | Fixed gain amplifier for automatic gain control and variable gain amplifier |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101102097A (en) * | 2006-07-07 | 2008-01-09 | 美国凹凸微系有限公司 | Fixed gain amplifier for automatic gain control and variable gain amplifier |
Non-Patent Citations (1)
| Title |
|---|
| An Energy-Efficient Analog Front-End Circuit for a Sub-1-V Digital Hearing Aid Chip;Sunyoung Kim elt.;《IEEE JOURNAL OF SOLID-STATE CIRCUITS》;20060430;第41卷(第4期);第2节-第3节，图2-图3 * |
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