CN114257211B - Variable bandwidth active RC filter and gain setting method thereof - Google Patents
Variable bandwidth active RC filter and gain setting method thereof Download PDFInfo
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- CN114257211B CN114257211B CN202210194877.3A CN202210194877A CN114257211B CN 114257211 B CN114257211 B CN 114257211B CN 202210194877 A CN202210194877 A CN 202210194877A CN 114257211 B CN114257211 B CN 114257211B
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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
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
Abstract
The invention discloses a variable bandwidth active RC filter and a gain setting method thereof, and relates to the RC filter adjusting technology. The scheme is provided aiming at how to ensure the gain adjustment precision on the premise of not increasing the circuit complexity in the prior art, the values required by each gain resistor are firstly calculated, and then the values are screened to find a group of combinations which can meet the requirements of gain and bandwidth adjustment and have the least number of resistors. The combined resistors are connected in parallel to form a gain resistor array. Compared with the method that different resistors are directly arranged for each gear, the gain resistor array RG has the advantages that the bit number of the gain resistor array RG reaches a minimum value, the circuit complexity is reduced, and the gain setting is simpler and more convenient.
Description
Technical Field
The invention relates to an RC filter adjusting technology, in particular to a variable bandwidth active RC filter and a gain setting method thereof.
Background
As shown in fig. 1, a typical first-order active RC filter is connected in parallel with an RC array at two ends of an operational amplifier, bandwidth adjustment is mainly performed through RP and CP in the RC array, and gain is adjusted through a gain resistor array RG which is arranged in front of the operational amplifier. Transmission letter thereofNumber is
(ii) a Gain of
(ii) a A 3dB bandwidth of
。
To increase bandwidth coverage, the RP needs to be designed to be variable. Gain and bandwidth are related to RP, so how to set the value and number of each single resistor in RG to ensure the gain adjustment accuracy without increasing circuit complexity is a problem that has been difficult to solve in the industry, where the structure of conventional RG is shown in fig. 2.
Disclosure of Invention
The present invention aims to provide a variable bandwidth active RC filter and a gain setting method thereof, so as to solve the problems of the prior art.
The invention discloses a gain setting method of a variable bandwidth active RC filter, which comprises the following steps:
bandwidth reducing resistor array RPThe possible resistance values of the gain are combined into an array RP, and the possible values of the gain are combined into an array GA;
all values of array RGx were calculated using array RP and array GA, where array RGx is bandwidth resistor array RPIs taken as the resistance value of RP [ x ]]Time-of-flight, required gain resistor array R at different gainsGThe resistance value of the resistor is formed into an array; x is the index of the array RP and the sequence number of the array RGx, and x is initialized to 0;
initializing an array RGA, the array RGA being a gain resistor array RGThe resistance values of the resistors in parallel connection form an array;
detecting current array RGA at bandwidth resistor array RPIs taken as the resistance value of RP [ x ]]If the gain requirements in the array GA are met, the next step is carried out, if the gain requirements in the array GA are met, the maximum value in the remaining elements of the array RGx is transferred to the array RGA, and the step is circulated;
checking whether the length of the array RP is equal to the length of the array RP after x is added by one, and if the length of the array RP is equal to the length of the array RP, performing gain resistance array R on the variable-bandwidth active RC filter according to each element in the current array RGAGAnd setting, and if not, returning to the previous step.
The array RGx is in descending order.
The first element of array RGx corresponding to each sequence number is transferred to array RGA, resulting in an initialized array RGA.
The array RP is in descending order.
The array GA is arranged in an ascending order.
The array RGAs are in descending order.
The invention relates to a variable bandwidth active RC filter, which is a gain resistor array R preposed at the input end of an operational amplifierGEach parallel resistor is set by the gain setting method.
Compared with the method for directly setting different resistors for each gear, the variable bandwidth active RC filter and the gain setting method thereof have the advantages that the bit number of the gain resistor array RG reaches a minimum value, the circuit complexity is reduced, and the gain setting is simpler and more convenient.
Drawings
Fig. 1 is a schematic diagram of a structure of a variable bandwidth active RC filter in the prior art.
Fig. 2 is a schematic diagram of a gain resistor array structure of a variable bandwidth active RC filter in the prior art.
Fig. 3 is a schematic flow chart of a gain setting method of a variable bandwidth active RC filter according to the present invention.
FIG. 4 is a schematic diagram of the RGA construction process in the present invention.
Fig. 5 is a graph of simulation of gain control and bandwidth adjustment for a variable bandwidth active RC filter in accordance with the present invention.
Reference numerals
RG: a gain resistor array;
RP: a bandwidth resistor array;
CP: a bandwidth capacitor array;
GA: a arrays of different gains;
RP: b resistor arrays R with different bandwidthsPAn array of resistances;
RGA: gain resistor array RGThe resistance values of the resistors in parallel connection form an array;
x: the index of the array RP and the sequence number of the array RGx;
RGx: bandwidth resistor array RPIs taken as the resistance value of RP [ x ]]Time-of-flight, required gain resistor array R at different gainsGThe resistance value of the resistor is formed into an array.
Detailed Description
As shown in fig. 3, the gain setting method of the variable bandwidth active RC filter according to the present invention is to set the gain of the variable bandwidth active RC filter to the bandwidth resistor array RPThe gain adjustment precision is ensured under the variable condition, and the gain resistor array R is changed by controlling the number of the conducted parallel resistorsGThe size of (2). The parallel resistor array can ensure that the resistance of the resistor in the array is larger and the overall resistance can be smaller, thereby reducing the influence of the switch parasitic resistance on the precision of the resistor array.
Bandwidth reducing resistor array RPThe values are arranged in descending order to form an array RP and a gain resistor array RGAll the parallel resistors in the array are arranged in descending order to form an array RGA, and the required gain values are arranged in ascending order to form an array GA. And let all array start indexes be 0, X be array RP end index, and N be array GA end index.
According to the common knowledge, calculating to obtain the bandwidth resistor array RPRespectively taking RP [0]，······，RP[X]Then, the resistance values of the gain resistor arrays required under different gains form each array RG0, RG1, RGX; these arrays are all arranged in descending order.
The initial array RGA is formed by taking the first element in the arrays RG0, RG1, RGX, and checking whether the bandwidth resistance array R is satisfiedPValue RP [0]If the time gain coverage requirement is not met, the rest maximum elements are sequentially taken from the RG0 and added into the array RGA until RP [0 ] is met]Corresponding toGain coverage requirements.
Satisfy RP [0 ]]After the gain coverage requirement of (1), check if RP 1 is satisfied]If the corresponding gain coverage requirement is not satisfied, the remaining maximum elements are sequentially taken from the array RG1 and added to the array RGA until RP [1 ] is satisfied]Corresponding gain coverage requirements. This step is repeated until RP [ X ]]Is also satisfied. Finally, outputting a final array RGA, wherein each element of the array RGA corresponds to a resistance value, and all the resistors are connected in parallel to form the gain resistor array RG。
According to the common knowledge of the circuit, the resistance value of the parallel connection of the plurality of resistors is smaller than the minimum value of the parallel resistors, the parallel connection of the large resistor can be equivalent to a small resistor, and the small resistor is not likely to generate a large resistor in the parallel connection. Therefore, when generating the array RGA, the requirement of the resistance of the large bandwidth resistor array is satisfied preferentially, and the requirement of the resistance of the small bandwidth resistor array can be satisfied at the same time. It is this method of array RGA generation that takes advantage of the invention, and the following details how the gain resistor array R is selected based on various parametersGThe value and number of the parallel resistors in (1).
Bandwidth setting resistor array RPThe gain range to be covered is 0-12dB and the stepping is 1dB, and the error is less than 0.1dB due to the fact that the gain range is 80K, 40K and 20K. The configuration of the RG is evaluated.
Using array RP and array GA to obtain:
RG0={80000,71300,63546,56635,50476,44987,40094,35734,31848,28385,25298,22547,20095}；
RG1={40000,35650,31773,28317,25238,22493,20047,17867,15924,14192,12649,11273,10047}；
RG2={20000,17825,15886,14158,12619,11246,10023,8933,7962,7096,6324,5636,5023}。
the first six elements of array RG0, the first element of array RG1, and the first two elements of array RG2 are selected by a loop check to form array RGA:
RGA={80000,71300,63546,56635,50476,44987,40000,20000,17825}。
according to the array RGA, nine resistors with resistance values respectively corresponding to the elements are connected in parallel to form the array RGAGain resistor array R of variable bandwidth active RC filterG. Then using nine-bit control signal RG<8:0>Controlling the conduction of these resistors, RG<x>A correspondingly large resistor is switched on for a high level.
The correspondence relationship between control signal RG <8:0> and actual resistances RG (Ω), RP (Ω), and gain is shown in the following table:
obtaining the gain resistor array RGAnd then carrying out simulation verification on the test piece. From the simulation results of FIG. 5, it can be seen that at different RPs [ x ]]The required gain adjustment range and accuracy are met.
It will be apparent to those skilled in the art that various other changes and modifications may be made in the above-described embodiments and concepts and all such changes and modifications are intended to be within the scope of the appended claims.
Claims (7)
1. A method for setting the gain of a variable bandwidth active RC filter, comprising the steps of:
bandwidth reducing resistor array RPThe possible resistance values of the gain are combined into an array RP, and the possible values of the gain are combined into an array GA;
all values of array RGx were calculated using array RP and array GA, where array RGx is bandwidth resistor array RPIs taken as the resistance value of RP [ x ]]Time-of-flight, required gain resistor array R at different gainsGThe resistance value of the resistor is formed into an array; x is the index of the array RP and the sequence number of the array RGx, and x is initialized to 0;
initializing an array RGA, the array RGA being a gain resistor array RGThe resistance values of the resistors in parallel connection form an array;
detecting current array RGA bandwidthResistor array RPIs taken as the resistance value of RP [ x ]]If the gain requirements in the array GA are met, the next step is carried out, if the gain requirements in the array GA are met, the maximum value in the remaining elements of the array RGx is transferred to the array RGA, and the step is circulated;
checking whether the length of the array RP is equal to the length of the array RP after x is added by one, and if the length of the array RP is equal to the length of the array RP, performing gain resistance array R on the variable-bandwidth active RC filter according to each element in the current array RGAGAnd setting, and if not, returning to the previous step.
2. The method as claimed in claim 1, wherein the array RGx is arranged in descending order.
3. The method as claimed in claim 2, wherein the first element of the array RGx in each sequence number is transferred to the array RGA to obtain an initialized array RGA.
4. The method as claimed in claim 1, wherein the array RP is arranged in descending order.
5. The method as claimed in claim 1, wherein the array GA is in ascending order.
6. The method of claim 1, wherein the RGAs are arranged in descending order.
7. A variable bandwidth active RC filter is characterized in that a gain resistor array R is arranged at the input end of an operational amplifier in advanceGIs set by the gain setting method of any of claims 1-6.
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Citations (4)
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|---|---|---|---|---|
| JP2008177897A (en) * | 2007-01-19 | 2008-07-31 | Matsushita Electric Ind Co Ltd | Gain control filter apparatus, gain control complex filter apparatus, and receiver |
| WO2009149651A1 (en) * | 2008-06-09 | 2009-12-17 | 慧帝科技(深圳)有限公司 | Variable resistor array and channel selection filter |
| CN102130679A (en) * | 2011-04-12 | 2011-07-20 | 广州润芯信息技术有限公司 | Active RC (Resistance-Capacitance) filter bandwidth calibration method |
| CN110830066A (en) * | 2019-12-12 | 2020-02-21 | 华中科技大学 | Multichannel bandwidth and gain adjustable signal processing system and method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7603098B2 (en) * | 2004-03-31 | 2009-10-13 | Broadcom Corporation | Programmable IF frequency filter for enabling a compromise between DC offset rejection and image rejection |
| US7352238B2 (en) * | 2006-06-21 | 2008-04-01 | Newport Media, Inc. | dB-linear analog variable gain amplifier (VGA) realization system and method |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008177897A (en) * | 2007-01-19 | 2008-07-31 | Matsushita Electric Ind Co Ltd | Gain control filter apparatus, gain control complex filter apparatus, and receiver |
| WO2009149651A1 (en) * | 2008-06-09 | 2009-12-17 | 慧帝科技(深圳)有限公司 | Variable resistor array and channel selection filter |
| CN102130679A (en) * | 2011-04-12 | 2011-07-20 | 广州润芯信息技术有限公司 | Active RC (Resistance-Capacitance) filter bandwidth calibration method |
| CN110830066A (en) * | 2019-12-12 | 2020-02-21 | 华中科技大学 | Multichannel bandwidth and gain adjustable signal processing system and method |
Non-Patent Citations (2)
| Title |
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| Qi He ; Chang-chun Bao.A gain-adaptive parallel HMM for speech enhancement.《2015 Asia-Pacific Signal and Information Processing Association Annual Summit and Conference (APSIPA)》.2015, * |
| 实现任意可编程放大器增益的电阻器阻值之考虑;Sid Levingston;《电子设计技术》;20061110(第11期);第116、120页 * |
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