CN110212886B - Second-order low-pass filter circuit based on current steering technology - Google Patents
Second-order low-pass filter circuit based on current steering technology Download PDFInfo
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
- H03H11/12—Frequency selective two-port networks using amplifiers with feedback
- H03H11/1213—Frequency selective two-port networks using amplifiers with feedback using transistor amplifiers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
- H03H11/12—Frequency selective two-port networks using amplifiers with feedback
- H03H11/126—Frequency selective two-port networks using amplifiers with feedback using a single operational amplifier
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
- H03H2011/0477—Frequency selective two-port networks using current feedback operational amplifiers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
- H03H2011/0488—Notch or bandstop filters
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Abstract
A second-order low-pass filter circuit based on a current steering technology is disclosed, wherein the input end of a first resistor is used as the input end of the second-order low-pass filter circuit, and the output end of the first resistor is connected with the input end of a third resistor; the lower polar plate of the second capacitor is connected with the output end of the third resistor and the output end of the operational amplifier and serves as the output end of the second-order low-pass filter circuit, and the upper polar plate is connected with the negative input end of the operational amplifier; the upper polar plate of the first capacitor is connected with the input end of the second resistor, and the lower polar plate is connected with the positive input end of the operational amplifier and is connected with the common-mode level; the first current steering module is used for dividing the current of the output end of the first resistor, flowing the current into the input end of the second resistor and flowing the current out of a signal path of the second-order low-pass filter circuit; the second current steering module is used for dividing the output end current of the second resistor into two parts of current, and then the two parts of current flow into the second capacitor and flow out of a signal path of the second-order low-pass filter circuit. The invention reduces the requirement of the low-pass filter on a large passive device and is convenient for on-chip integration.
Description
Technical Field
The invention belongs to the technical field of analog integrated circuits, and particularly relates to a circuit structure for realizing high-order low-pass filtering by adopting an analog mode based on a current steering technology.
Background
With the rapid development of biomedical and bioelectronic industries, the demand of consumer medical electronic products is increasing. Various sensor acquisition and readout circuits are used to detect and process different bioelectrical signals. On the other hand, CMOS integrated circuit design and fabrication tend to be high density, high speed, and high precision, with more and more functions being integrated inside the chip to reduce power consumption and cost. There are many types of bioelectric signals, and the common ones include Electrocardiographic (ECG), Electromyographic (EMG), electroencephalographic (EEG), Electrooculographic (EOG), and the like. Several signals are commonly seen in fig. 1, within a certain frequency range. A bioelectric signal detection and processing system requires an analog front-end circuit that functions to filter and amplify the bioelectric signal, which is generally at a lower frequency and has a larger time constant. A common second-order low-pass filter is shown in fig. 2, and a large resistor and a large capacitor are required by adopting the design method. The cut-off angular frequency expression of such a second-order low-pass filter is as follows:
in a common integrated circuit process, the on-chip resistance does not exceed 1M omega, the capacitance does not exceed 100pF, and a large resistor and capacitor occupy a very large layout area, so that a low-pass filtering function with very low cut-off frequency cannot be realized on a chip. To solve these problems, the academia has proposed methods such as a filtering scheme using a switched capacitor circuit and using a transconductance operational amplifier. The switched capacitor circuit has high switching noise, the scheme using transconductance has a complex structure, a plurality of operational amplifiers are used, the power consumption is high, and the linear working range is small.
Disclosure of Invention
Aiming at the problem that a passive device (resistor capacitor) is difficult to integrate on a chip due to the fact that low-pass cut-off frequency in a traditional second-order low-pass filter circuit is low, the invention provides the second-order low-pass filter circuit based on the current steering technology.
The technical scheme of the invention is as follows:
a second-order low-pass filter circuit based on current steering technology comprises a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor and an operational amplifier,
the input end of the first resistor is used as the input end of the second-order low-pass filter circuit, and the output end of the first resistor is connected with the input end of the third resistor;
the lower electrode plate of the second capacitor is connected with the output end of the third resistor and the output end of the operational amplifier and serves as the output end of the second-order low-pass filter circuit, and the upper electrode plate of the second capacitor is connected with the negative input end of the operational amplifier;
the upper polar plate of the first capacitor is connected with the input end of the second resistor, and the lower polar plate of the first capacitor is connected with the positive input end of the operational amplifier and is connected with the common-mode level;
the second order low pass filter circuit further comprises a first current steering module and a second current steering module,
the input end of the first current steering module is connected with the output end of the first resistor and is used for dividing the current at the output end of the first resistor into two parts of current, one part of the current with smaller current value flows into the input end of the second resistor after division, and the other part of the current flows out of a signal path of the second-order low-pass filter circuit;
the input end of the second current steering module is connected with the output end of the second resistor and is used for dividing the current of the output end of the second resistor into two parts of current, one part of the current with smaller current value flows into the second capacitor after the current is divided, and the other part of the current flows out of a signal path of the second-order low-pass filter circuit.
Specifically, the first current steering module comprises a first NMOS tube and a second NMOS tube,
the grid electrode of the first NMOS tube is connected with a first bias voltage, the drain electrode of the first NMOS tube is connected with the drain electrode of the second NMOS tube and is used as the input end of the first current steering module, and the source electrode of the first NMOS tube is connected with a common mode level;
the grid electrode of the second NMOS tube is connected with a second bias voltage, and the source electrode of the second NMOS tube is connected with the input end of the second resistor;
the size of the first NMOS tube is larger than that of the second NMOS tube;
the second current steering module comprises a third NMOS tube and a fourth NMOS tube,
the grid electrode of the third NMOS tube is connected with a first bias voltage, the drain electrode of the third NMOS tube is connected with the drain electrode of the fourth NMOS tube and serves as the input end of the second current steering module, and the source electrode of the third NMOS tube is connected with a common mode level;
the grid electrode of the fourth NMOS tube is connected with a second bias voltage, and the source electrode of the fourth NMOS tube is connected with the upper polar plate of the second capacitor;
the size of the third NMOS tube is larger than that of the fourth NMOS tube.
Specifically, the size of the first NMOS transistor is 10 times that of the second NMOS transistor, and the size of the third NMOS transistor is 10 times that of the fourth NMOS transistor.
Specifically, the first bias voltage and the second bias voltage are both adjustable bias voltages.
Specifically, the voltage value of the second bias voltage is half of the voltage value of the first bias voltage, and the first bias voltage is a power supply voltage.
Specifically, the operational amplifier comprises a fifth NMOS transistor, a sixth NMOS transistor, a seventh NMOS transistor, an eighth NMOS transistor, a ninth NMOS transistor, a first PMOS transistor, a second PMOS transistor, a third PMOS transistor, a fourth PMOS transistor, a Miller compensation capacitor and a load capacitor,
the grid electrode of the third PMOS tube is used as the negative input end of the operational amplifier, the source electrode of the third PMOS tube is connected with the source electrode of the fourth PMOS tube and the drain electrode of the first PMOS tube, and the drain electrode of the third PMOS tube is connected with the drain electrode of the eighth NMOS tube, the grid electrode of the fifth NMOS tube and the grid electrode of the sixth NMOS tube;
the grid electrode of the fourth PMOS tube is used as the positive input end of the operational amplifier, and the drain electrode of the fourth PMOS tube is connected with the grid electrode of the seventh NMOS tube and the drain electrode of the ninth NMOS tube;
the grid electrode of the second PMOS tube is connected with the grid electrode of the first PMOS tube and is connected with a third bias voltage, the source electrode of the second PMOS tube is connected with the source electrode of the first PMOS tube and is connected with a power voltage, and the drain electrode of the second PMOS tube is connected with the drain electrode of the seventh NMOS tube and is used as the output end of the operational amplifier;
the load capacitor is connected between the output end of the operational amplifier and the ground;
the grid electrode of the eighth NMOS tube is connected with the grid electrode of the ninth NMOS tube and the fourth bias voltage, and the source electrode of the eighth NMOS tube is connected with the drain electrode of the fifth NMOS tube;
the drain electrode of the sixth NMOS tube is connected with the source electrode of the ninth NMOS tube and is connected with the output end of the operational amplifier after passing through the Miller compensation capacitor, and the source electrode of the sixth NMOS tube is connected with the source electrodes of the fifth NMOS tube and the seventh NMOS tube and is grounded.
The invention has the beneficial effects that: according to the invention, two current steering modules are introduced to a resistance path of the second-order low-pass filter to realize current shunting, and an attenuation factor can be formed in a transfer function of the low-pass filter, so that the second-order low-pass filter provided by the invention can obtain a lower low-pass cut-off frequency under the condition that a passive device is kept small enough, and the on-chip integration of the low-pass filter is realized; the first bias voltage and the second bias voltage in the current rudder are adjustable, and the low-pass filter can obtain better low-pass filtering characteristics by selecting proper voltage bias.
Drawings
Fig. 1 is a frequency distribution diagram of several common bioelectric signals.
Fig. 2 is a schematic structural diagram of a conventional second-order low-pass filter.
Fig. 3 is a schematic diagram of an implementation structure of a current rudder.
Fig. 4 is a schematic diagram of an implementation structure of a double-ended input single-ended output operational amplifier.
Fig. 5 is a schematic diagram of an implementation structure of a second-order low-pass filter based on a current steering technique according to an embodiment of the present invention.
Detailed Description
The invention is further illustrated by way of example with reference to the accompanying drawings.
As shown in fig. 2, which is a schematic structural diagram of a conventional second-order low-pass filter, the first current steering module and the second current steering module are added to a resistance path of the low-pass filter to shunt current, so that an attenuation factor α can be formed in a transfer function of the low-pass filter, and a lower low-pass cut-off frequency can be obtained under the condition that a passive device is kept small enough, so as to realize on-chip integration of the low-pass filter.
The current rudder is used for current splitting, for example, fig. 3 is a current rudder structure capable of current splitting, and the technical solution of the present invention is described in detail below by taking the current rudder of the structure of fig. 3 as an example. Fig. 5 shows a second-order low-pass filter circuit in the present embodiment, which includes a first current steering module CST1, a second current steering module CST2, and a first resistor R1A second resistor R2A third resistor R3A first capacitor C1A second capacitor C2And a high-gain operational amplifier OP with double-ended input and single-ended output. The first current steering module CST1 includes a first NMOS transistor M1 and a second NMOS transistor M2, and the second current steering module CST2 includes a third NMOS transistor M3 and a fourth NMOS transistor M4. A first resistor R1The input end of the second-order low-pass filter provided by the invention is connected with an input signal Vin, and the output end of the second-order low-pass filter is connected with a third resistor R3The input terminal of the first current steering module CST1 is connected to the drain terminals of the first NMOS transistor M1 and the second NMOS transistor M2. The gate end of the first NMOS transistor M1 and the gate end of the third NMOS transistor M3 are connected to a first bias voltage Vb1, and the source end of the first NMOS transistor M1 is connected to the source end of the third NMOS transistor M3 and the positive input end of the operational amplifier OP, and is connected to a common mode level Vcm. The gate terminal of the second NMOS transistor M2 and the gate terminal of the fourth NMOS transistor M4 are connected to a second bias voltage Vb 2. A second resistor R2Is connected with the source end of the second NMOS transistor M2 in the first current steering module CST1 and the first capacitor C1Upper plate of, the first capacitor C1The lower plate of (2) is connected with a common mode level Vcm. A second resistor R2The output terminal of the second current steering module CST2 is connected to the drain terminals of the third NMOS transistor M3 and the fourth NMOS transistor M4. Second capacitor C2The upper polar plate is connected with the negative input end of the operational amplifier OP, and the lower polar plate is connected with the output end of the operational amplifier OP and is used as the output end of the second-order low-pass filter provided by the invention. Third resistor R3Is connected to the output of the operational amplifier OP.
First NMOS transistor M1 and second NMOThe S-pipe M2 is two shunt pipes of the first current steering module CST1, and the third NMOS pipe M3 and the fourth NMOS pipe M4 are two shunt pipes of the second current steering module CST2, in order to couple the first resistor R1Current at output terminal and second resistor R2And the current of the output end is divided, a larger part of the divided current flows out of a signal path of the second-order low-pass filter circuit, and the smaller part of the divided current is connected according to the original path. Since the current flowing through the first NMOS transistor M1 is greater than the current flowing through the second NMOS transistor M2, and the current flowing through the third NMOS transistor M3 is greater than the current flowing through the fourth NMOS transistor M4, the size of the first NMOS transistor M1 is greater than the size of the second NMOS transistor M2, and the size of the third NMOS transistor M3 is greater than the size of the fourth NMOS transistor M4, considering the tradeoff between the size of the MOS transistors and the current distribution, in some embodiments, the size of the first NMOS transistor is 10 times that of the second NMOS transistor, and the size of the third NMOS transistor is 10 times that of the fourth NMOS transistor.
In some embodiments, the first bias voltage Vb1 and the second bias voltage Vb2 connected to the MOS transistors in the current steering module may be provided by an adjustable bias voltage generating circuit, so that the bias voltage values of the first bias voltage Vb1 and the second bias voltage Vb2 are adjustable, and selecting an appropriate voltage bias enables the low-pass filter to obtain a good low-pass filtering characteristic.
In some embodiments, the voltage value of the second bias voltage may be set to be half of the voltage value of the first bias voltage, wherein the first bias voltage may adopt a power supply voltage. The purpose of this arrangement is to expect the first NMOS transistor M1 to operate in the linear region and the second NMOS transistor M2 to operate in the subthreshold region, so as to ensure that the current flowing through the first NMOS transistor M1 is much larger than the current flowing through the second NMOS transistor M2.
The operational amplifier OP is a double-end input single-end output structure, and as shown in fig. 4, provides a structure for implementing a high-gain double-end input single-end output operational amplifier, including a fifth NMOS transistor M5, a sixth NMOS transistor M6, a seventh NMOS transistor M7, an eighth NMOS transistor M12, a ninth NMOS transistor M13, a first PMOS transistor M8, a second PMOS transistor M9, a third PMOS transistor M10, a fourth PMOS transistor M11, a compensation capacitor C3And a load capacitor C4The third PMOS transistor M10 and the fourth PMOS transistor M11 areThe input pair transistors of the operational amplifier, the grid electrode of the third PMOS transistor M10 is used as the negative input end of the operational amplifier, the source electrode is connected with the source electrode of the fourth PMOS transistor M11 and the drain electrode of the first PMOS transistor M8, and the drain electrode is connected with the drain electrode of the eighth NMOS transistor M12, the grid electrode of the fifth NMOS transistor M5 and the grid electrode of the sixth NMOS transistor M6; the grid electrode of the fourth PMOS tube M11 is used as the positive input end of the operational amplifier, and the drain electrode thereof is connected with the grid electrode of the seventh NMOS tube M7 and the drain electrode of the ninth NMOS tube M13; the grid electrode of the second PMOS tube M9 is connected with the grid electrode of the first PMOS tube M8 and is connected with the third bias voltage VP, the source electrode of the second PMOS tube M9 is connected with the source electrode of the first PMOS tube M8 and is connected with the power supply voltage VDD, and the drain electrode of the second PMOS tube M9 is connected with the drain electrode of the seventh NMOS tube M7 and is used as the output end of the operational amplifier; load capacitor C for compensating secondary dominant pole4The output end of the operational amplifier is connected with the ground; the gate of the eighth NMOS transistor M12 is connected to the gate of the ninth NMOS transistor M13 and the fourth bias voltage VN, and the source thereof is connected to the drain of the fifth NMOS transistor M5; the drain of the sixth NMOS transistor M6 is connected to the source of the ninth NMOS transistor M13 via a compensation capacitor C3Then the output end of the operational amplifier is connected, and the source electrodes of the operational amplifier are connected with the source electrodes of the fifth NMOS tube M5 and the seventh NMOS tube M7 and are grounded GND.
The working principle of the embodiment is as follows:
when the circuit module normally operates, the first NMOS transistor M1 and the second NMOS transistor M2 of the first current steering module CST1 operate in a linear region and a sub-threshold region, respectively. When the tube works in the sub-threshold region, the current can be controlled at a very small level, so that the voltages at the source and the drain of the sub-threshold tube tend to be equal. Setting a first resistance R1At an output terminal voltage of V1The currents flowing through the first and second NMOS transistors M1 and M2 of the first current steering module CST1 are I2And I1And satisfies the following relationship:
the currents flowing through the third and fourth NMOS transistors M3 and M4 of the second current steering module CST2 are I5And I4Total current is I3And is andthe following relationship is satisfied:
α1and alpha2Is the attenuation factor of the first current steering module CST1 and the second current steering module CST 2.
From kirchhoff's circuit law, one can obtain:
I4＝-VO*C2s
V1＝I3*R2
the simplification is as follows:
the transfer function of the low-pass filter of the present embodiment is obtained as:
as can be seen from the above transfer function, the low-pass cut-off frequency of the second-order low-pass filter in this embodiment is:
assuming a second resistance R2And a third resistor R3The resistance values are equal to R, and the first capacitor C1And a second capacitor C2Equal to C, the current decay factor α of the first current steering module CST11And the current decay factor alpha of the second current steering module CST22If the equality is α, then the low-pass cut-off frequency can be rewritten as follows:
the first current steering module CST1 and the second current steering module CST2 shunt current across the low pass filter resistor path such that it flows through the second resistor R2And a second capacitor C2The current is greatly reduced, the time constant of the circuit is increased, the realization of very small low-pass cut-off frequency is realized, and the on-chip integration is facilitated.
In this embodiment, although the current rudder with the structure shown in fig. 3 is taken as an example for description, other current rudders capable of achieving shunt are also applicable to the technical solution of the present invention, to sum up, the current of the second-order low-pass filter circuit based on the current rudder technology provided by the present invention is shunted by the first current rudder module CST1 and the second current rudder module CST2, so that the time constant of the circuit is increased and a lower low-pass cut-off frequency is obtained while smaller passive devices (resistors and capacitors) are maintained, so as to facilitate on-chip integration.
Although the circuit contents of the second-order low-pass filter implemented based on the current steering technique of the present invention have been disclosed in the form of examples, it is not intended to limit the present invention, and those skilled in the art should make insubstantial changes or modifications without departing from the spirit of the present invention, and therefore, they should fall within the protection scope of the appended claims.
Claims (6)
1. A second-order low-pass filter circuit based on current steering technology comprises a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor and an operational amplifier,
the input end of the first resistor is used as the input end of the second-order low-pass filter circuit, and the output end of the first resistor is connected with the input end of the third resistor;
the lower electrode plate of the second capacitor is connected with the output end of the third resistor and the output end of the operational amplifier and serves as the output end of the second-order low-pass filter circuit, and the upper electrode plate of the second capacitor is connected with the negative input end of the operational amplifier;
the upper polar plate of the first capacitor is connected with the input end of the second resistor, and the lower polar plate of the first capacitor is connected with the positive input end of the operational amplifier and is connected with the common-mode level;
characterized in that the second-order low-pass filter circuit also comprises a first current steering module and a second current steering module,
the input end of the first current steering module is connected with the output end of the first resistor and is used for dividing the current at the output end of the first resistor into two parts of current, one part of the current with smaller current value flows into the input end of the second resistor after division, and the other part of the current flows out of a signal path of the second-order low-pass filter circuit;
the input end of the second current steering module is connected with the output end of the second resistor and is used for dividing the current of the output end of the second resistor into two parts of current, one part of the current with smaller current value flows into the second capacitor after the current is divided, and the other part of the current flows out of a signal path of the second-order low-pass filter circuit.
2. The current steering technique-based second-order low-pass filter circuit of claim 1, wherein the first current steering module comprises a first NMOS transistor and a second NMOS transistor,
the grid electrode of the first NMOS tube is connected with a first bias voltage, the drain electrode of the first NMOS tube is connected with the drain electrode of the second NMOS tube and is used as the input end of the first current steering module, and the source electrode of the first NMOS tube is connected with a common mode level;
the grid electrode of the second NMOS tube is connected with a second bias voltage, and the source electrode of the second NMOS tube is connected with the input end of the second resistor;
the size of the first NMOS tube is larger than that of the second NMOS tube;
the second current steering module comprises a third NMOS tube and a fourth NMOS tube,
the grid electrode of the third NMOS tube is connected with a first bias voltage, the drain electrode of the third NMOS tube is connected with the drain electrode of the fourth NMOS tube and serves as the input end of the second current steering module, and the source electrode of the third NMOS tube is connected with a common mode level;
the grid electrode of the fourth NMOS tube is connected with a second bias voltage, and the source electrode of the fourth NMOS tube is connected with the upper polar plate of the second capacitor;
the size of the third NMOS tube is larger than that of the fourth NMOS tube.
3. The current steering technique-based second-order low-pass filter circuit of claim 2, wherein the size of the first NMOS transistor is 10 times the size of the second NMOS transistor, and the size of the third NMOS transistor is 10 times the size of the fourth NMOS transistor.
4. The current steering technique-based second-order low-pass filter circuit of claim 2 or 3, wherein the first and second bias voltages are both adjustable bias voltages.
5. The second-order low-pass filter circuit based on the current steering technology according to claim 2 or 3, wherein the voltage value of the second bias voltage is half of the voltage value of the first bias voltage, and the first bias voltage is a power supply voltage.
6. The second-order low-pass filter circuit based on the current steering technology as claimed in claim 1, wherein the operational amplifier comprises a fifth NMOS transistor, a sixth NMOS transistor, a seventh NMOS transistor, an eighth NMOS transistor, a ninth NMOS transistor, a first PMOS transistor, a second PMOS transistor, a third PMOS transistor, a fourth PMOS transistor, a Mailer compensation capacitor and a load capacitor,
the grid electrode of the third PMOS tube is used as the negative input end of the operational amplifier, the source electrode of the third PMOS tube is connected with the source electrode of the fourth PMOS tube and the drain electrode of the first PMOS tube, and the drain electrode of the third PMOS tube is connected with the drain electrode of the eighth NMOS tube, the grid electrode of the fifth NMOS tube and the grid electrode of the sixth NMOS tube;
the grid electrode of the fourth PMOS tube is used as the positive input end of the operational amplifier, and the drain electrode of the fourth PMOS tube is connected with the grid electrode of the seventh NMOS tube and the drain electrode of the ninth NMOS tube;
the grid electrode of the second PMOS tube is connected with the grid electrode of the first PMOS tube and is connected with a third bias voltage, the source electrode of the second PMOS tube is connected with the source electrode of the first PMOS tube and is connected with a power voltage, and the drain electrode of the second PMOS tube is connected with the drain electrode of the seventh NMOS tube and is used as the output end of the operational amplifier;
the load capacitor is connected between the output end of the operational amplifier and the ground;
the grid electrode of the eighth NMOS tube is connected with the grid electrode of the ninth NMOS tube and the fourth bias voltage, and the source electrode of the eighth NMOS tube is connected with the drain electrode of the fifth NMOS tube;
the drain electrode of the sixth NMOS tube is connected with the source electrode of the ninth NMOS tube and is connected with the output end of the operational amplifier after passing through the Miller compensation capacitor, and the source electrode of the sixth NMOS tube is connected with the source electrodes of the fifth NMOS tube and the seventh NMOS tube and is grounded.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1751963A1 (en) * | 2004-05-25 | 2007-02-14 | STMicroelectronics S.r.l. | Circuit for reconstructing an analog signal from a digital signal and transmission system, particularly for wcdma cellular telephony, including such circuit |
| CN101267208A (en) * | 2008-05-06 | 2008-09-17 | 无锡紫芯集成电路系统有限公司 | A simulation low-pass filter |
| CN105958965A (en) * | 2016-04-27 | 2016-09-21 | 华中科技大学 | Low-pass filter applied to human physiological signals |
-
2019
- 2019-07-17 CN CN201910644932.2A patent/CN110212886B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1751963A1 (en) * | 2004-05-25 | 2007-02-14 | STMicroelectronics S.r.l. | Circuit for reconstructing an analog signal from a digital signal and transmission system, particularly for wcdma cellular telephony, including such circuit |
| CN101267208A (en) * | 2008-05-06 | 2008-09-17 | 无锡紫芯集成电路系统有限公司 | A simulation low-pass filter |
| CN105958965A (en) * | 2016-04-27 | 2016-09-21 | 华中科技大学 | Low-pass filter applied to human physiological signals |
Non-Patent Citations (1)
| Title |
|---|
| 新型心电信号检测带通滤波器的设计;庞宇 等;《重庆邮电大学学报(自然科学版)》;20150228;第27卷(第2期);224-228 * |
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| CN110212886A (en) | 2019-09-06 |
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