CN108365826B - Programmable gain amplifier - Google Patents
Programmable gain amplifier Download PDFInfo
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- CN108365826B CN108365826B CN201711431388.0A CN201711431388A CN108365826B CN 108365826 B CN108365826 B CN 108365826B CN 201711431388 A CN201711431388 A CN 201711431388A CN 108365826 B CN108365826 B CN 108365826B
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- resistor
- operational amplifier
- dac
- programmable gain
- amplifier
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- 229920005994 diacetyl cellulose Polymers 0.000 description 26
- 230000003321 amplification Effects 0.000 description 5
- 238000003199 nucleic acid amplification method Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3089—Control of digital or coded signals
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- Control Of Amplification And Gain Control (AREA)
- Analogue/Digital Conversion (AREA)
Abstract
The invention relates to a programmable gain amplifier, wherein a multiplication type DAC in the programmable gain amplifier is provided with a serial interface or a parallel interface, and is formed by combining an inverted T-shaped resistor network in the multiplication type DAC and an operational amplifier, wherein the feedback end of a high-precision weight resistor network in the multiplication type DAC is the signal input end of the operational amplifier, and the reference end is the output feedback end of the operational amplifier. The invention has the advantages of simple design, small volume, convenient control, high precision, flexible use and low cost.
Description
Technical Field
The present invention relates to a programmable gain amplifier.
Background
With the use of computers, in order to reduce hardware devices, a Programmable gain amplifier (PGA: programmable GAIN AMPLIFIER), which is a very versatile amplifier whose amplification factor can be controlled by a program as needed, may be used. By adopting the amplifier, the amplification factor can be adjusted by a program, so that the full-scale signal of the A/D converter is uniform, and the measurement accuracy is greatly improved. The automatic range conversion is to automatically adjust the multiple of the processed signal by using a programmable gain amplifier according to the requirement so as to meet the requirements of subsequent circuits and systems.
At present, the programmable gain amplifier has two kinds of combined PGA and integrated PGA, the combined PGA is generally composed of an operational amplifier, an instrument amplifier or an isolated discharger and some other additional circuits, the working principle is that the value of a feedback resistor which is connected with a multiplexing switch is adjusted through a program, so that the amplification factor of the amplifier is adjusted, the combined PGA is flexible in design, the PGA with various amplification factors can be easily designed, but the combined PGA is complex in design, huge in circuit size and low in precision. The programmable gain amplifier circuit specially designed is integrated PGA, and the types of integrated PGA circuits are many, such as MCP6S21, MCP6S22, MCP6S26 and MCP6S28 series produced by micro chip corporation of America, AD8321 produced by Analog Devices of Analog instruments of America, etc., belong to the programmable gain amplifier, and the integrated PGA has the advantages of simple use, small volume and high precision, but has the limitations of practical circuit design due to the expensive cost, particularly the PGA with multiple gain choices.
Disclosure of Invention
The invention aims to provide a design method of a programmable gain amplifier, which has the advantages of flexible design, low cost, simple use, small volume and high precision of the integrated PGA.
The technical scheme adopted by the invention is as follows: the programmable gain amplifier is characterized by comprising a multiplication DAC and an operational amplifier, wherein the feedback end of a high-precision weight resistor network in the multiplication DAC is an operational amplifier signal input end, and the reference end is an output feedback end of the operational amplifier.
The programmable gain amplifier is characterized in that a multiplication type DAC in the programmable gain amplifier is provided with a serial interface or a parallel interface, and is formed by combining an inverted T-shaped resistor network and an operational amplifier in the multiplication type DAC.
The invention has the following beneficial effects: (1) The design is simple, the volume is greatly reduced, and only two chips are needed; (2) The control is simple, the precision is high, the gain precision is ensured by utilizing a high-precision weight resistor network in the multiplication DAC, and the control of the gain can be realized only by controlling Dn of the DAC; (3) The PGA with various bandwidths and different gain stages can be combined by changing different multiplication DACs and operational amplifiers, for example, the DACs can be selected from 8 bits to 16 bits; if the DAC and the operational amplifier which are packaged in the same way are selected, the PCB is not required to be modified when the bandwidth or the gain level of the PGA is modified, and the requirements of the volume and the control speed of the PCB (the volume of the serial DAC is small, the control speed of the parallel DAC is high) can be met by selecting the serial DAC or the parallel DAC, and the serial DAC or the parallel DAC can correspond to the singlechips or the controllers of different interfaces; (4) The cost is low, and the scheme is far lower than the integrated PGA under the condition of the same amplification gain stage number.
Drawings
Fig. 1 is a schematic diagram of the internal resistor network structure of the 12-bit multiplying DAC of the present invention.
Fig. 2 is an internal structure diagram of a 12-bit serial multiplication DAC of the present invention.
Fig. 3 is an internal structure diagram of a 12-bit parallel multiplying DAC of the present invention.
Fig. 4 is a schematic diagram of the connection of the present invention.
Detailed Description
The invention will be further illustrated with reference to specific examples.
Referring to fig. 1, the multiplying DAC belongs to an R-2R type DAC, i.e. an inverted-T resistor network D/a converter,
Referring to fig. 2 or 3, the multiplying DAC may be a multiplying DAC having a serial interface or a parallel interface.
Referring to fig. 4, the programmable gain amplifier is composed of a multiplication DAC and an operational amplifier, the multiplication DAC is simplified to 4 bits, the feedback terminal RFB port of the high-precision weight resistor network in the multiplication DAC is the signal input terminal of the operational amplifier, the reference terminal VREF terminal is the output feedback terminal of the operational amplifier, S3, S2, S1 and S0 are 4 internal electronic switches, their states are controlled by the values of the input codes d3, d2, d1 and d0, the switch is connected to V-when the code is 1, and the switch is connected to v+ when the code is 0. When the operational amplifier is used as an inverting amplifier, the V-level and the V+ level are equal and close to zero, and no matter which side the switch is connected to, the current flowing through each branch is always unchanged when the operational amplifier is connected to the ground. The equivalent resistance of the weighted resistor network part is R, and if the total output current is I, the current flowing through each branch is I/2, I/4, I/8 and I/16 respectively, wherein I=VOUT/R. The programmable method for realizing the gain of the whole circuit comprises the following steps:
1. If the switch Si is grounded (connected to the v+ of the amplifier) when di=0 and Si is connected to the input V-of the amplifier when di=1, dn is known from fig. 4
2. The input end has VSIN= -Ri sigma, and is substituted with I=VOUT/R to obtain
3. For a multiplying DAC with n-bit input, the output analog voltage formula is
Dn is an n-bit binary number ranging from 0 to 2 n -1.
4. The above description shows that the output voltage is inversely related to the input digital quantity, and the gain of the whole circuit is
5. Conclusion: the gain of the whole circuit can be programmable by controlling the value of Dn.
Claims (2)
1. The programmable gain amplifier is characterized by comprising a multiplication DAC and an operational amplifier, wherein a feedback end RFB end of a high-precision weight resistor network in the multiplication DAC is an operational amplifier signal input end, a reference end VREF end is an output feedback end of the operational amplifier, an input end corresponding to the voltage VSIN of an external input signal is connected with the feedback end RFB end, the feedback end RFB end is connected with a first end of an equivalent resistor, a second end of the equivalent resistor is respectively connected with a first end of each electronic switch, and the feedback end VREF end is connected with a negative input end V-end of the operational amplifier; the positive input end of the operational amplifier is respectively connected with the second ends of the electronic switches and connected with the first end of the first 2R resistor of the current-driven R-2R resistor ladder network; the third end of each electronic switch is correspondingly connected with the first ends of the rest 2R resistors of the R-2R resistor ladder network driven by current respectively, and the second end of the first 2R resistor is connected with the second end of the next 2R resistor; the other 2R resistances except the first 2R resistance are all in parallel connection; and each other 2R resistor is separated by one R resistor, and the R resistors are in series connection, and the number of the 2R resistors of the current-driven R-2R resistor ladder network is one more than that of the R resistors; the second end of the last 2R resistor is connected with the VREF end and is used as an output feedback end of the operational amplifier; the equivalent resistance of the weight resistor network part is R, if the output total current is I, wherein I=VOUT/R; if di=0, the switch Si is grounded, and if di=1, the switch Si is connected to the input end of the operational amplifier, and for the n-bit input multiplication DAC, the output analog voltage formula is:
wherein VSIN is the voltage of the external input signal.
2. A programmable gain amplifier according to claim 1, characterized in that the multiplying DAC in the programmable gain amplifier has a serial interface or a parallel interface and is formed by combining an inverted-T resistor network inside the multiplying DAC with an operational amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711431388.0A CN108365826B (en) | 2017-12-26 | 2017-12-26 | Programmable gain amplifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711431388.0A CN108365826B (en) | 2017-12-26 | 2017-12-26 | Programmable gain amplifier |
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| Publication Number | Publication Date |
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| CN108365826A CN108365826A (en) | 2018-08-03 |
| CN108365826B true CN108365826B (en) | 2024-07-12 |
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| CN201711431388.0A Active CN108365826B (en) | 2017-12-26 | 2017-12-26 | Programmable gain amplifier |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110365303A (en) * | 2019-07-11 | 2019-10-22 | 厦门大学嘉庚学院 | Controllable gain amplifier and control method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105203089A (en) * | 2015-09-30 | 2015-12-30 | 中国人民解放军海军工程大学 | Selsyn solid-state axial angle sending system |
| CN207677696U (en) * | 2017-12-26 | 2018-07-31 | 浙江禾川科技股份有限公司 | A Programmable Gain Amplifier |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101207399B (en) * | 2006-12-06 | 2014-06-04 | 美国博通公司 | Method and system for controlling circuit in an emitter |
| CN103248330B (en) * | 2013-01-31 | 2015-10-21 | 南京邮电大学 | A kind of programmable gain amplifier of high-gain precision |
| US20170126196A1 (en) * | 2015-11-02 | 2017-05-04 | Ess Technology, Inc. | Low Noise Audio Rendering Circuit |
| CN105515472B (en) * | 2016-01-25 | 2018-05-25 | 南京凌鸥创芯电子有限公司 | Motor drive current detection circuit and control system |
| CN105743454B (en) * | 2016-01-31 | 2018-12-04 | 天津大学 | A kind of binary weights dB linear switch resistor-type CMOS programmable gain amplifier |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105203089A (en) * | 2015-09-30 | 2015-12-30 | 中国人民解放军海军工程大学 | Selsyn solid-state axial angle sending system |
| CN207677696U (en) * | 2017-12-26 | 2018-07-31 | 浙江禾川科技股份有限公司 | A Programmable Gain Amplifier |
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