CN104579235B - A kind of low-power consumption transconductance capacitor (GmC) biquadratic Structure Filter - Google Patents
A kind of low-power consumption transconductance capacitor (GmC) biquadratic Structure Filter Download PDFInfo
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- CN104579235B CN104579235B CN201510029714.XA CN201510029714A CN104579235B CN 104579235 B CN104579235 B CN 104579235B CN 201510029714 A CN201510029714 A CN 201510029714A CN 104579235 B CN104579235 B CN 104579235B
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Abstract
The invention belongs to wave filter technology field, specially a kind of low-power consumption transconductance capacitor (GmC) biquadratic Structure Filter.The present invention is based on common-mode feedback principle, using two kinds of different pseudo-differential OTA structures in a biquadratic structure, utilizes OTA itself DC current gain two common mode feedback loops of formation so that the DC level of each node inside circuit is stable to be preferably worth.The circuit that power consumption is consumed in the biquadratic structure that the present invention is designed only includes basic OTA amplifying circuits and two difference amplifiers, and the power consumption of difference amplifier can be made low, therefore the power consumption of the circuit of whole biquadratic structure is determined by each OTA mutual conductance amplifying circuit substantially, and does not interfere with while reduction power consumption the performance of wave filter.However, needing extra circuit to consume to realize the stabilization of common mode electrical level using the conventional design method of pseudo differential architectures, it is unfavorable for low-power consumption application.
Description
Technical field
The invention belongs to wave filter technology field, the transconductance capacitor of biquadratic structure is specifically related to（Gm-C）Wave filter.
Background technology
Analog filter is the critically important module of ABB process part of Radio-Frequency Wireless Communication chip, and it is acted on
It is to realize the suppression to out-of-band interference, and has decisive role to the bit error rate of whole communication system.Meanwhile, filtering
The power consumption of device occupies very big proportion in whole radio-frequency transmitter, and raising and filter order with filter characteristic frequency
Several increases, can be such that power consumption proportionally increases, it is impossible to meet low work(using the design method of some traditional low-frequency filters
The requirement of consumption.
Traditional wave filter is the OTA-C filter using same pseudo differential architectures OTA, its basic structure such as Fig. 1
It is shown.
Biquadratic structure GmIn-C filter circuits, power consumption can be divided into following two parts：（1）Consumed by OTA amplifier tube
Power consumption,（2）In order to stablize the power consumption that the auxiliary circuit of quiescent point is consumed.Therefore saving power consumption has two approach：（1）Choosing
With the OTA structures of low-power consumption,（2）Reduce the power consumption of other auxiliary circuits.Yet with the limitation of circuit structure, often this two side
Face requires to meet simultaneously.
Therefore, the wave filter of low-power consumption is designed, it is significant to reduction radio-frequency transmitter SoC overall powers.
The content of the invention
It is an object of the invention to design a kind of transconductance capacitor (G of low-power consumptionm- C) biquadratic Structure Filter.
Transconductance capacitor (the G that the present invention is designedm- C) biquadratic Structure Filter is to traditional same artifact of use
Separation structure OTA OTA-C filter is improved, its structure as shown in Fig. 2 including operation transconductance amplifier OTA1,
OTA2, OTA3, OTA4, resistance R1, R2, R3, R4, R5, R6, difference amplifier AP1 and AP2, load capacitance C1 and C2；Wherein, lead to
Cross common mode detection circuit（It is made up of resistance R5 and R6）Detection calculations trsanscondutance amplifier OTA3 output end common mode electrical level, is input to
A difference amplifier AP2 input and withMagnitude of voltage (For the reference voltage given of outside) to amplify it more afterwards poor
Value, the difference signal level after amplification is fed back to by big resistance R1 and R2 OTA1 grid, forms first common-mode feedback
Loop；Circuit is detected by common mode（It is made up of resistance R3 and R4）Detection calculations trsanscondutance amplifier OTA1, OTA2 and OTA3 is public
Output node common mode electrical level, be input to difference amplifier AP1 an input and withAmplify it after magnitude of voltage
Difference, the difference signal after amplification is connected to the offset side of OTA3 current source load（In Vtu2 and Fig. 4 in corresponding diagram 2
Vb）, form second common mode feedback loop.
C1 and C2 is the load capacitance of wave filter itself in Fig. 2.In Fig. 2, OTA2 positive-negative output end is respectively coupled phase
Load capacitance C1 with size to ground, OTA3 positive-negative output end connect respectively the load capacitance C2 of formed objects to.
In the present invention, operation transconductance amplifier OTA1, OTA2 and OTA4 are using the pseudo differential architectures based on phase inverter (as schemed
Shown in 3), the positive-negative polarity of input and output is marked in figure.The OTA of two single ended input Single-end outputs constitutes artifact side by side
Separation structure.In figure 3, n pipes are connected with the grid of p pipes as input, the drain electrode phase continuous cropping of n pipes and p pipes in a single-ended OTA
For output end.N pipe source grounds, p pipe source electrodes meet power supply Vdd.N is managed and p pipes are all operated in saturation region, inverter structure
OTA equivalent transconductance is equal to n pipes and p pipe mutual conductance sums.OTA3 is using the pseudo differential architectures for having current source load（Such as Fig. 4 institutes
Show）, in the OTA of wherein one single ended input Single-end output, p pipes are current source load, and the grid of p pipes is used as offset side, n pipes
Grid be used as input.N is managed and p pipes are all operated in saturation region.Mutual conductance equivalent single-ended OTA is equal to the mutual conductance of n pipes.Two this
The grid of the single-ended OTA of sample p pipes, which is connected, is used as public offset side（Vb in Fig. 4）.
The wherein OTA based on phase inverter（Shown in Fig. 3）Due to current multiplexing, power consumption can be saved.
Operation transconductance amplifier OTA1 grid uses Capacitance Coupled, has completely cut off the DC level of front stage circuits to rear class electricity
The influence on road.
Resistance R1, R2, R3, R4, R5, R6 shown in Fig. 2 are realized with the metal-oxide-semiconductor for being operated in subthreshold value, it is possible to achieve foot
Enough big equivalent resistances, need not unusual big coupling in OTA1 input to realize detection and the direct current biasing to common mode electrical level
Close electric capacity and achieve that low-frequency cut-off frequency, in tens k hertz of rank, does not result in the notable deterioration of the receiver bit error rate.
Because first order OTA input uses Capacitance Coupled, the mismatch and DC maladjustment of front stage circuits common mode electrical level are not
Influence can be produced on subordinate's circuit.Two common mode feedback loops only need to suppress in this grade of wave filter due to the mistake of metal-oxide-semiconductor in OTA
Skew with caused DC level.The power consumption of a complete biquad filter only includes four OTA master in the design
Amplifying circuit and two difference amplifiers.Difference amplifier do not need big bandwidth only to amplify DC level, therefore power consumption can be done
It is very low.
In the present invention, OTA1, OTA2, OTA4 use the pseudo differential architectures based on phase inverter, and OTA3, which is used, has current source to bear
The pseudo differential architectures of load, using Capacitance Coupled so that the OTA of inverter structure has and had current source load or tail current structure
The similar quiescent point control characteristics of OTA.Therefore the pseudo-differential OTA current multiplexings based on phase inverter had both been remained and have saved work(
The advantage of consumption, and form the effect that common mode feedback loop reaches stable common mode electrical level using OTA itself DC current gain, it is not necessary to
Extra OTA in parallel controls common mode electrical level, and the wave filter of whole biquadratic structure only includes OTA amplifying circuits and two difference
Amplifying circuit, therefore greatly reduce power consumption.
Brief description of the drawings
Fig. 1 is general biquadratic（Biquad）Structure chart, the output end identified in figureFor low pass output end.
Fig. 2 is biquad filter circuit structure proposed by the present invention.
The circuit structure that Fig. 3 uses for OTA1, OTA2 and OTA4 in the present invention.
The circuit structure that Fig. 4 uses for OTA3 in the present invention.
Fig. 5 is general biquadratic structure（Biquad）Single-ended Simplified equivalent model.
Fig. 6 is output nodeThe stable dynamic process of common mode electrical level, transverse axis is the time（Unit s）, the longitudinal axis is voltage
（Unit V）.
Embodiment
The Biquad biquadratic Structure Filters of foundation of the present invention, as shown in Figure 1.Considered based on the linearity, OTA selections are pseudo-
Differential configuration.The OTA of pseudo differential architectures generally can be divided into two kinds, and a kind of is based on the phase inverter knot loaded without fixed current source
Structure, a kind of is the structure for having fixed current source to load.The former only needs the latter near due to current multiplexing when realizing identical mutual conductance
The power consumption of half.But in terms of suppression common mode signal, the former generally requires extra OTA and is connected to output end to control electricity
It is flat, power consumption is added, the latter need to only adjust current source bias voltage.Therefore, in order to while utilizing the two advantage, this hair
It is bright to propose wave filter as shown in Figure 2, wherein OTA circuit structures as shown in Figure 3 and Figure 4.
The equivalent model that single-ended biquadratic structure simplifies is as shown in Figure 5.For each OTA transconductance value.
R is in figureWith OTA1, the parallel value of OTA4 output impedances, ro is OTA3 output impedance, and C1, C2 is load capacitance.It is right
For biquadratic structural circuit, there are two class nodes inside circuit, as shown in figure 4, one kind is low pass output node b, it is a kind of
It is band logical output node a.By the static gate voltage for finely tuning OTA1（Vtu1 in Fig. 2）Or OTA3
Current source bias voltage (Vb in Vtu2 or Fig. 4 in Fig. 2) DC level of a points and b points can be changed.
Keep OTA3 current source bias voltage constant（）, OTA1 grid voltage increase, can list following
Relational expression：
（1）
Wherein I represents to inject the increased electric currents of R.OTA1 grid ends can further be obtained to point a and to point by solving I expression formula
B DC current gain：
（2）
（3）
Keep OTA1 grid end voltage constant（）, when OTA3 current source load bias terminal voltage increase, can
List following relationship：
（4）
WhereinRepresent the increased magnitudes of voltage of point a.It is assumed herein that OTA3 NMOS and PMOS mutual conductance is equal, i.e.,.SolveExpression formula to can obtain OTA3 current source load offset side straight to point a and point b
Flow enhancement：
（5）
（6）
On the premise of the gain of wave filter is in more than 0dB（）, it is ensured that in any transconductance value
In the case of selection, in some cases（In order to improve the linearityValue beSeveral times, such as）It can cause。WithIt is big
The small influence to common mode feedback loop gain, analysis sees below.
Existing two schemes can realize point a and point b DC levels determination.
Scheme 1：Detection a point DC levels feed back to OTA1 grid end, and the current source that detection b level points feed back to OTA3 is born
The offset side of load, the loop DC gain of two common-mode feedbacks is respectively：
（7）
（8）
The gain of respectively two differential amplifier circuits.In order to realize that node a and b quiescent point to the greatest extent may be used
Can be close to ideal value, it is desirable to.Therefore it is required that：
（9）
Scheme 2：Detection a point DC levels feed back to the offset side of OTA3 current source load, and detection b point direct currents are redressed
OTA1 grid end is fed to, the loop DC gain of two common-mode feedbacks is respectively：
（10）
（11）
The gain of respectively two differential amplifier circuits.
Similarly require
（12）
（13）
It was found from the contrast of two schemes, scheme 2 requires lower to the yield value of differential comparison amplifying circuit, therefore can be with
Save more power consumptions.
Understood based on scheme 2, the output end of OTA1 grid end to OTA3（B points）Common mode DC current gain,
The offset side (Vb in Vtu2 or Fig. 4 in Fig. 2) of OTA3 load current sources is to the public output node of OTA2, OTA4（A points）Be total to
Mould DC current gain is.Therefore when the common mode electrical level of a points or b points deviates desired value, two difference amplifiers are produced
Regulate signal a points and b points can be caused to come back to desired value under the collective effect of two loops.3 width figures are OTA3 in Fig. 6
Output end（B points）Gradually stable dynamic process of the DC level in the case where difference amplifier AP2 gains take different value（Gain according to
Secondary increase）, desired value is.Fluctuation in figure in the visible big stabilization process with gain change is more obvious, and phase is abundant
Degree is tapered into.
It is in terms of the protrusion improvement of the present invention, using Capacitance Coupled so that the OTA of inverter structure has and had electric current
Source load or tail current structure the similar control characteristics of OTA.Both the pseudo-differential OTA current multiplexing sections based on phase inverter had been remained
The advantage of power consumption is saved, and the effect that common mode feedback loop reaches stable common mode electrical level is formed using OTA itself DC current gain, no
Extra OTA is needed to control common mode electrical level.Analyze two kinds of common mode feedback loop Choices simultaneously, it is proposed that a kind of relatively low
The design of power consumption.The biquadratic structure designed based on the present invention（Gm-C）The power consumption of wave filter amplifies electricity by OTA mutual conductance
Road is determined, and wherein three OTA are the characteristics of have low-power consumption.In actual applications, each OTA mutual conductance is distributed according to demand
Value, and the power consumption proportion that the power consumption of other auxiliary circuits accounts for whole biquad filter can be preferably minimized.
Claims (2)
1. a kind of transconductance capacitor (Gm- C) biquadratic Structure Filter, it is characterised in that including：Operation transconductance amplifier OTA1,
OTA2, OTA3, OTA4, resistance R1, R2, R3, R4, R5, R6, load capacitance C1 and C2, difference amplifier AP1 and AP2；Wherein, by
The common mode detection electric circuit inspection operation transconductance amplifier OTA3 of resistance R5 and R6 composition output end common mode electrical level, is input to difference
An amplifier AP2 input and withAmplify its difference after magnitude of voltage, the difference signal level after amplification is passed through
Resistance R1 and R2 feed back to OTA1 grid, form first common mode feedback loop；The common mode detection being made up of resistance R3 and R4
The common mode electrical level of output node public electric circuit inspection operation transconductance amplifier OTA1, OTA2 and OTA3, is input to difference amplifier
An AP1 input and withAmplify its difference after magnitude of voltage, the difference signal after amplification is connected to OTA3's
The offset side of current source load, forms second common mode feedback loop；Operation transconductance amplifier OTA2 positive-negative output end all divides
Not Lian Jie formed objects load capacitance C1 to ground, operation transconductance amplifier OTA3 positive-negative output end connects formed objects respectively
Load capacitance C2 to ground；
The operation transconductance amplifier OTA1, OTA2 and OTA4 use the pseudo differential architectures based on phase inverter, and OTA3, which is used, electricity
The pseudo differential architectures of stream source load.
2. transconductance capacitor (G according to claim 1m- C) biquadratic Structure Filter, it is characterised in that resistance R1, R2,
R3, R4, R5, R6 are realized by the metal-oxide-semiconductor for being operated in subthreshold value.
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| CN201510029714.XA CN104579235B (en) | 2015-01-21 | 2015-01-21 | A kind of low-power consumption transconductance capacitor (GmC) biquadratic Structure Filter |
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| CN201510029714.XA CN104579235B (en) | 2015-01-21 | 2015-01-21 | A kind of low-power consumption transconductance capacitor (GmC) biquadratic Structure Filter |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105743448B (en) * | 2016-01-31 | 2018-10-30 | 天津大学 | A kind of adjustable high linearity trsanscondutance amplifier structure for Gm-C filters |
| CN106208984A (en) * | 2016-07-12 | 2016-12-07 | 天津大学 | High linearity trsanscondutance amplifier for the broad tuning scope of multimode Gm C wave filter |
| CN106253856A (en) * | 2016-07-18 | 2016-12-21 | 天津大学 | A kind of high-gain, low noise just bias adjustment type cascade trans-impedance amplifier |
| CN108768324B (en) * | 2017-12-28 | 2022-01-11 | 北京时代民芯科技有限公司 | Substrate modulation common mode feedback circuit applied to output stage with inverter structure |
| CN109194304B (en) * | 2018-07-13 | 2023-02-14 | 厦门芯豪科技有限公司 | Band-pass filter suitable for physiological signal processing |
| CN112969270A (en) * | 2021-02-07 | 2021-06-15 | 深圳市美矽微半导体有限公司 | Voltage self-adaption method, system, equipment and storage medium based on power carrier |
| CN114448384B (en) * | 2022-02-09 | 2023-07-21 | 深圳市九天睿芯科技有限公司 | Filtering circuit |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5764100A (en) * | 1997-02-13 | 1998-06-09 | Motorola, Inc. | Filter |
| CN101867354A (en) * | 2010-05-06 | 2010-10-20 | 复旦大学 | Frequency self-tuning circuit used for Gm-C filter |
-
2015
- 2015-01-21 CN CN201510029714.XA patent/CN104579235B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5764100A (en) * | 1997-02-13 | 1998-06-09 | Motorola, Inc. | Filter |
| CN101867354A (en) * | 2010-05-06 | 2010-10-20 | 复旦大学 | Frequency self-tuning circuit used for Gm-C filter |
Non-Patent Citations (1)
| Title |
|---|
| 应用于OFDM超宽带***中的0.18μm Gm-C滤波器和可变增益放大器的设计;姚望等;《复旦学报(自然科学版)》;20081231;第47卷(第6期);第755-762页 * |
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