CN102361437B - Adaptive low pass filter - Google Patents
Adaptive low pass filter Download PDFInfo
- Publication number
- CN102361437B CN102361437B CN201110327498.9A CN201110327498A CN102361437B CN 102361437 B CN102361437 B CN 102361437B CN 201110327498 A CN201110327498 A CN 201110327498A CN 102361437 B CN102361437 B CN 102361437B
- Authority
- CN
- China
- Prior art keywords
- frequency
- pin
- pass filter
- signal
- circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Networks Using Active Elements (AREA)
Abstract
本发明提供了一种自适应低通滤波器，主要包括整形电路、频率电压转换电路和低通滤波电路，首先将待测信号分两路，一路输入整形电路将输入信号变换为脉冲信号，然后将该脉冲信号输入到频率电压转换电路，将输入的脉冲信号转换成电压信号，再将该电压信号输入到低通滤波电路的模拟乘法器的一端，通过该电压信号间接调节滤波器的截止频率，另一路信号直接输入到低通滤波电路中模拟乘法器的另一端，从而实现截止频率到输入频率的自动适应。该自适应低通滤波器利用频率电压转换的原理同时结合模拟乘法器而实现，电路结构简单、实时性好、成本低、调节方便，适用于不同应用领域所处理信号的频率在较大范围变化的需要。
The invention provides an adaptive low-pass filter, which mainly includes a shaping circuit, a frequency-voltage conversion circuit and a low-pass filtering circuit. Input the pulse signal to the frequency-voltage conversion circuit, convert the input pulse signal into a voltage signal, and then input the voltage signal to one end of the analog multiplier of the low-pass filter circuit, and indirectly adjust the cut-off frequency of the filter through the voltage signal , the other signal is directly input to the other end of the analog multiplier in the low-pass filter circuit, so as to realize the automatic adaptation of the cut-off frequency to the input frequency. The adaptive low-pass filter is realized by using the principle of frequency-to-voltage conversion and combined with an analog multiplier. The circuit structure is simple, the real-time performance is good, the cost is low, and the adjustment is convenient. needs.
Description
技术领域 technical field
本发明属于滤波器技术领域，具体地说涉及一种自适应低通滤波器。 The invention belongs to the technical field of filters, in particular to an adaptive low-pass filter.
背景技术 Background technique
目前，滤波器是无线电技术中许多设计问题的中心，在数据采集、信号处理和通信系统等领域有着广泛的应用。其中低通滤波器更是许多信号处理过程中的必要环节。在信号频率范围较窄的场合可采用截止频率固定的低通滤波器进行滤波。但是在很多应用领域所处理信号的频率在较大范围变化，这时采用截止频率固定的低通滤波器很难满足要求，就需要设计截止频率可变的低通滤波器。 Filters are currently at the center of many design issues in radio technology and have a wide range of applications in areas such as data acquisition, signal processing, and communication systems. Among them, the low-pass filter is a necessary link in many signal processing processes. In the case of a narrow signal frequency range, a low-pass filter with a fixed cut-off frequency can be used for filtering. However, in many application fields, the frequency of the processed signal varies in a large range. At this time, it is difficult to meet the requirements with a low-pass filter with a fixed cut-off frequency, so it is necessary to design a low-pass filter with a variable cut-off frequency.
现阶段实现截止频率可变的现有技术是：一是采用电容电阻网络以及模拟开关构建的可调截止频率的低通滤波器，这种实现方式精度不高、控制复杂、实时性差，而且由于各部分电容差异的存在对信号幅度和相位都会造成不可预料的影响；二是直接利用一些单片有源滤波芯片，通过时钟控制滤波频率，但构成的滤波电路噪声较大，且大范围跟踪频率的误差较大。 At this stage, the existing technologies for realizing variable cut-off frequency are as follows: one is a low-pass filter with adjustable cut-off frequency constructed by capacitor-resistor network and analog switch. The existence of capacitance differences in various parts will have unpredictable effects on the signal amplitude and phase; the second is to directly use some single-chip active filter chips to control the filter frequency through the clock, but the filter circuit is noisy and tracks the frequency in a wide range. The error is larger.
发明内容 Contents of the invention
本发明的目的在于提供一种电路结构简单、实时性好、成本低、调节方便的自适应低通滤波器，以解决现有技术中采用截止频率固定的低通滤波器，很难满足许多应用领域所处理信号的频率在较大范围变化要求这一技术问题。 The purpose of the present invention is to provide an adaptive low-pass filter with simple circuit structure, good real-time performance, low cost and convenient adjustment, so as to solve the problem that the low-pass filter with fixed cut-off frequency in the prior art is difficult to meet many applications. The frequency of the signal processed in the field changes in a large range to ask for this technical problem.
为实现上述目的，本发明采取的技术方案是： For realizing above-mentioned object, the technical scheme that the present invention takes is:
一种自适应低通滤波器，包括整形电路、频率电压转换电路及低通滤波电路，待测信号分为两路：一路待测信号输入到整形电路进行整形，将待测信号整形为脉冲信号，将该脉冲信号输入到频率电压转换电路，经过频率电压转换电路将该脉冲信号转换成电压信号，再将该电压信号输入到低通滤波电路中模拟乘法器的一端；另一路待测信号直接输入到低通滤波电路中模拟乘法器的另一端，经过低通滤波电路后，实现截止频率到输入频率的自动适应。 An adaptive low-pass filter, including a shaping circuit, a frequency-voltage conversion circuit, and a low-pass filtering circuit. The signal to be tested is divided into two paths: one path of the signal to be tested is input to the shaping circuit for shaping, and the signal to be tested is shaped into a pulse signal , input the pulse signal to the frequency-voltage conversion circuit, convert the pulse signal into a voltage signal through the frequency-voltage conversion circuit, and then input the voltage signal to one end of the analog multiplier in the low-pass filter circuit; the other signal to be tested is directly Input to the other end of the analog multiplier in the low-pass filter circuit, after passing through the low-pass filter circuit, the automatic adaptation of the cut-off frequency to the input frequency is realized.
所述的整形电路中定时器选用的是NE555。 The timer used in the shaping circuit is NE555.
所述的频率电压转换电路中频率电压转换芯片选用的是LM331。 The frequency-voltage conversion chip in the frequency-voltage conversion circuit is LM331.
所述的低通滤波电路中模拟乘法器采用四通道、四象限电压输出形式的MLT04。 The analog multiplier in the low-pass filter circuit adopts MLT04 in the form of four-channel, four-quadrant voltage output.
本发明提供的上述自适应低通滤波器，是一种纯硬件电路设计实现方式，主要由整形电路、频率电压转换电路和低通滤波电路构成，充分利用了频率电压转换器和模拟乘法器的优点，电路结构简单、实时性好、成本低、调节方便，能够实现滤波器的截止频率根据待测信号频率自动适应的目的，适用于不同应用领域所处理信号的频率在较大范围变化的需要。另外，该自适应低通滤波器的整形电路定时器选用的是NE555，具有结构简单、实用方便、实时性好，能有效清除信号中掺杂的噪声等特点；频率电压转换电路中频率电压转换芯片选用LM331，充分利用了LM331的优点，设计的频率电压转换电路具有良好的线性度且转换误差能减小到0.01%；低通滤波电路中模拟乘法器选用MLT04，实现乘法运算无需外接其他元件，构成的电路结构简单、温度稳定性好且功耗低。 The above-mentioned self-adaptive low-pass filter provided by the present invention is a pure hardware circuit design and implementation method, mainly composed of a shaping circuit, a frequency-voltage conversion circuit and a low-pass filter circuit, and fully utilizes the functions of the frequency-voltage converter and the analog multiplier. Advantages: simple circuit structure, good real-time performance, low cost, convenient adjustment, can realize the purpose of automatically adapting the cut-off frequency of the filter according to the frequency of the signal to be tested, and is suitable for the needs of the frequency of the signal processed in different application fields changing in a wide range . In addition, the shaping circuit timer of the adaptive low-pass filter is NE555, which has the characteristics of simple structure, practical and convenient, good real-time performance, and can effectively remove the noise doped in the signal; the frequency-voltage conversion circuit in the frequency-voltage conversion circuit The chip uses LM331, which makes full use of the advantages of LM331. The designed frequency-voltage conversion circuit has good linearity and the conversion error can be reduced to 0.01%. , the circuit structure is simple, the temperature stability is good and the power consumption is low.
附图说明 Description of drawings
图1是本发明的结构框图； Fig. 1 is a block diagram of the present invention;
图2 是整形电路原理图； Figure 2 is a schematic diagram of the shaping circuit;
图3是频率电压转换电路原理图； Fig. 3 is a schematic diagram of a frequency-to-voltage conversion circuit;
图4是低通滤波电路原理图。 Figure 4 is a schematic diagram of the low-pass filter circuit.
具体实施方式 Detailed ways
下面结合具体实施方式及其附图对本发明技术方案作进一步详细说明： The technical solution of the present invention will be described in further detail below in conjunction with specific implementation methods and accompanying drawings:
图1为本发明的结构框图。如图1所示，本发明包括整形电路1、频率电压转换电路2和低通滤波电路3，其中，整形电路1的作用是将正弦信号整形为脉冲信号；频率电压转换电路2的作用就是将输入的脉冲信号转换为电压信号输出，输出的电压信号能与输入的脉冲频率成线性关系,并可通过测量其输出端的电压值来间接测量输入的脉冲频率；低通滤波电路3中起主要作用的是模拟乘法器，其作用是实现信号的相乘。具体电路设计为：待测信号Vi分别接入整形电路1和低通滤波电路3；频率电压转换电路2分别与整形电路1和低通滤波电路3连接。待测信号Vi分两路，一路待测信号进入整形电路1，经过整形电路1后的待测信号被整形为脉冲信号V1，该脉冲信号V1进入频率电压转换电路2，将脉冲信号V1转换成电压信号V2，转换后的电压信号V2再进入低通滤波电路3中乘法器的一端，通过该电压信号间接调节滤波器的截止频率；另一路待测信号进入低通滤波电路3中的模拟乘法器的另一端，经过低通滤波电路后实现截止频率到输入频率的自适应。 Fig. 1 is a structural block diagram of the present invention. As shown in Figure 1, the present invention comprises shaping circuit 1, frequency-voltage conversion circuit 2 and low-pass filter circuit 3, wherein, the effect of shaping circuit 1 is to shape the sinusoidal signal into pulse signal; The effect of frequency-voltage conversion circuit 2 is exactly The input pulse signal is converted into a voltage signal output, and the output voltage signal can be linearly related to the input pulse frequency, and the input pulse frequency can be indirectly measured by measuring the voltage value at the output terminal; the low-pass filter circuit 3 plays a major role What is an analog multiplier, its function is to realize the multiplication of signals. The specific circuit design is: the signal V i to be tested is respectively connected to the shaping circuit 1 and the low-pass filter circuit 3; the frequency-voltage conversion circuit 2 is connected to the shaping circuit 1 and the low-pass filtering circuit 3 respectively. The signal to be tested V i is divided into two channels, one channel of the signal to be tested enters the shaping circuit 1, and the signal to be tested after passing through the shaping circuit 1 is shaped into a pulse signal V 1 , and the pulse signal V 1 enters the frequency-voltage conversion circuit 2 to convert the pulse signal V 1 is converted into a voltage signal V 2 , and the converted voltage signal V 2 enters one end of the multiplier in the low-pass filter circuit 3, and indirectly adjusts the cut-off frequency of the filter through the voltage signal; the other signal to be measured enters the low-pass filter The other end of the analog multiplier in circuit 3 realizes the adaptation from the cutoff frequency to the input frequency after passing through the low-pass filter circuit.
图2为整形电路原理图。结合图1、图2，本发明的整形电路通过定时器NE555和一些特定值的电阻电容构成。具体包括：U1为定时器NE555、R1和R2都为10K电阻、C1和C2都为0.01uF电容。其中：U1的第6引脚和第2引脚接电容C1的同一端，同时第6引脚接电阻R2的一端，第2引脚接电阻R1的一端。电容C1的另一端接待测信号Vi，电阻R1的另一端接电源+5v，电阻R2的另一端接电源地GND。U1的第5引脚接电容C2的一端,电容C2的另一端接电源地GND。U1的第1引脚也接电源地GND，U1的第4引脚和第8引脚接电源+5v,U1的第7引脚悬空，U1的第3引脚为整形后脉冲信号V1输出端。 Figure 2 is a schematic diagram of the shaping circuit. With reference to Fig. 1 and Fig. 2, the shaping circuit of the present invention is composed of a timer NE555 and some resistors and capacitors with specific values. Specifically include: U 1 is a timer NE555, R 1 and R 2 are 10K resistors, C 1 and C 2 are 0.01uF capacitors. Among them: the 6th pin and the 2nd pin of U1 are connected to the same end of the capacitor C1 , while the 6th pin is connected to one end of the resistor R2 , and the second pin is connected to one end of the resistor R1 . The other end of the capacitor C 1 receives the test signal V i , the other end of the resistor R 1 is connected to the power supply +5v, and the other end of the resistor R 2 is connected to the power ground GND. The fifth pin of U1 is connected to one end of the capacitor C2 , and the other end of the capacitor C2 is connected to the power ground GND. The 1st pin of U 1 is also connected to the power ground GND, the 4th and 8th pins of U 1 are connected to the power supply +5v, the 7th pin of U 1 is suspended, and the 3rd pin of U 1 is the pulse after shaping signal V1 output.
图3是本发明的频率电压转换电路原理图。结合图1、图3，本发明的频率电压转换电路由频率电压转换芯片LM331和一些特定值的电阻电容构成。具体包括：U2为频率电压转换芯片LM331、C3为470pF电容、R3、R4为10K电阻，R5为68K电阻、R8为12K电阻、R9为5K电位器、C5为0.1uF电容、R6、R7为待定电阻、C4为待定电容。其中：U2的第6引脚接电容C3、电阻R3的一端，电容C3的另一端接脉冲信号V1，电阻R3的另一端接电源+15v。U2的第7引脚同时接电阻R4、电阻R5的一端，电阻R4的另一端接电源+15v， 电阻R5的另一端接电源地GND。U2的第2引脚接电阻R8的一端，电阻R8的另一端接滑动变阻器R9的一端 ，滑动变阻器R9的另一端接电源地GND 。U2的第3、4引脚都接电源地GND。U2的第5引脚同时接电阻R6和电容C4的一端，电阻R6的另一端接电源+15v，电容C4的另一端接电源地GND。U2的第1引脚同时接电阻R7和电容C5的一端，电容C5和电阻R7的另一端同时接电源地GND。同时U2 的第1引脚也作为转换后的电压信号V2的输出端。U2的第8引脚接电源+15v。脉冲信号经过频率电压转换电路后，输出的电压与输入的脉冲信号的频率之间的关系式如1式所示： Fig. 3 is a schematic diagram of the frequency-to-voltage conversion circuit of the present invention. Referring to Fig. 1 and Fig. 3, the frequency-voltage conversion circuit of the present invention is composed of a frequency-voltage conversion chip LM331 and some resistors and capacitors with specific values. Specifically include: U 2 is a frequency-voltage conversion chip LM331, C 3 is a 470pF capacitor, R 3 and R 4 are 10K resistors, R 5 is a 68K resistor, R 8 is a 12K resistor, R 9 is a 5K potentiometer, and C 5 is 0.1 uF capacitor, R 6 and R 7 are undetermined resistors, and C 4 is undetermined capacitor. Among them: the sixth pin of U 2 is connected to capacitor C 3 and one end of resistor R 3 , the other end of capacitor C 3 is connected to pulse signal V 1 , and the other end of resistor R 3 is connected to power supply +15v. The 7th pin of U 2 is connected to one end of the resistor R 4 and the resistor R 5 at the same time, the other end of the resistor R 4 is connected to the power supply +15v, and the other end of the resistor R 5 is connected to the power ground GND. The second pin of U2 is connected to one end of the resistor R8 , the other end of the resistor R8 is connected to one end of the sliding rheostat R9 , and the other end of the sliding rheostat R9 is connected to the power ground GND. Both pins 3 and 4 of U 2 are connected to the power ground GND. The fifth pin of U 2 is connected to the resistor R 6 and one end of the capacitor C 4 at the same time, the other end of the resistor R 6 is connected to the power supply +15v, and the other end of the capacitor C 4 is connected to the power ground GND. The first pin of U 2 is connected to one end of the resistor R 7 and the capacitor C 5 at the same time, and the other end of the capacitor C 5 and the resistor R 7 is connected to the power ground GND at the same time. At the same time, the first pin of U 2 also serves as the output end of the converted voltage signal V 2 . The 8th pin of U 2 is connected to the power supply +15v. After the pulse signal passes through the frequency-voltage conversion circuit, the relationship between the output voltage and the frequency of the input pulse signal is shown in formula 1:
（1） (1)
（1）式中为待测信号Vi的频率，电阻Rs的值为，由（1）式可以看出只要合理改变电容值和电阻值就可以改变输出电压与输入频率之间的线性关系。 (1) where is the frequency of the signal V i to be tested, and the value of the resistor R s is , it can be seen from formula (1) that as long as the capacitance value and resistance value are changed reasonably, the linear relationship between the output voltage and the input frequency can be changed.
图4为本发明的低通滤波电路原理图。结合图1、图4，本发明的低通滤波电路由模拟乘法器MLT04、运算放大器OP284和一些电阻电容构成。具体包括：U3为模拟乘法器MLT04、U4为运算放大器OP284，R10、R11、R12为待定电阻，C6、C7、C8、C9为0.1uF 滤波电容、C10为待定电容。其中U3的第3引脚接经过频率电压转换后的电压信号V2，U3的第4引脚接电阻R10、R12的一端，电阻R10的另一端接待测信号Vi，电阻R12的另一端接U4的第6引脚。U3的第5引脚同时接电源+5v和滤波电容C6的一端，滤波电容C6的另一端接电源地GND，U3的第14引脚同时接电源-5v和滤波电容C7的一端，电容C7的另一端接电源地，U3的第2引脚接电源地GND；U3的第1引脚接电阻R11的一端，电阻R11的另一端接U4的第2引脚，同时U4的第2引脚接电容C10的一端，电容C10的另一端接U4的第6引脚。U4的第1、5引脚和第8引脚悬空。U4的第7引脚同时接电源+12v和滤波电容C9一端，滤波电容C9另一端接电源地GND，U4的第4引脚同时接电源-12v和滤波电容C8的一端，滤波电容C8的另一端接电源地GND，U4的第3引脚接电源地GND。 Fig. 4 is a schematic diagram of the low-pass filter circuit of the present invention. 1 and 4, the low-pass filter circuit of the present invention is composed of an analog multiplier MLT04, an operational amplifier OP284 and some resistors and capacitors. Specifically include: U 3 is an analog multiplier MLT04, U 4 is an operational amplifier OP284, R 10 , R 11 , and R 12 are resistors to be determined, C 6 , C 7 , C 8 , and C 9 are 0.1uF filter capacitors, and C 10 is Pending capacitance. Among them, the third pin of U 3 is connected to the voltage signal V 2 after frequency-voltage conversion, the fourth pin of U 3 is connected to one end of resistors R 10 and R 12 , the other end of resistor R 10 receives the test signal V i , and the resistor The other end of R12 is connected to the sixth pin of U4 . The 5th pin of U 3 is connected to the power supply +5v and one end of the filter capacitor C 6 at the same time, the other end of the filter capacitor C 6 is connected to the power ground GND, and the 14th pin of U 3 is connected to the power supply -5v and the filter capacitor C 7 at the same time One end, the other end of the capacitor C 7 is connected to the power ground, the second pin of U 3 is connected to the power ground GND; the first pin of U 3 is connected to one end of the resistor R 11 , and the other end of the resistor R 11 is connected to the second end of U 4 pin, while the second pin of U4 is connected to one end of capacitor C10 , and the other end of capacitor C10 is connected to the sixth pin of U4 . The 1st, 5th and 8th pins of U4 are floating. The 7th pin of U 4 is connected to the power supply +12v and one end of the filter capacitor C 9 at the same time, the other end of the filter capacitor C 9 is connected to the power ground GND, and the 4th pin of U 4 is connected to the power supply -12v and one end of the filter capacitor C 8 at the same time. The other end of the filter capacitor C 8 is connected to the power ground GND, and the third pin of U 4 is connected to the power ground GND.
结合基尔霍夫定律及图1至图4可以得到系统的传递函数为： Combined with Kirchhoff's law and Figures 1 to 4, the transfer function of the system can be obtained as:
(2) (2)
与一般一阶低通滤波器的传递函数对比得截止角频率，增益因子，由于V2由（1）式可得那么截止频率为： The transfer function of the general first-order low-pass filter Compared to the cut-off angular frequency , gain factor , since V 2 can be obtained from (1) then the cut-off frequency for:
（3） (3)
从上式可以看出只要合理选择电阻电容的大小就可以实现截止频率与待测信号频率的线性关系。考虑到MLT04最大输入电压为2.5v，LM331最大转换频率为10k选择合适的参数：、、、、、。从而得： It can be seen from the above formula that the linear relationship between the cut-off frequency and the frequency of the signal to be measured can be realized as long as the size of the resistor and capacitor is reasonably selected. Considering that the maximum input voltage of MLT04 is 2.5v, and the maximum conversion frequency of LM331 is 10k, choose the appropriate parameters: , , , , , . Thus:
（4） (4)
这样就可实现对截止频率自适应的作用。 In this way, the function of self-adaptation to the cut-off frequency can be realized.
本发明提供的上述自适应低通滤波器，其电路设计是利用频率电压转换的原理同时结合模拟乘法器实现的。首先将待测信号分两路，一路待测信号输入NE555构成的整形电路对待测信号整形，将待测信号变换为脉冲信号，然后将该脉冲信号输入到由LM331及电阻电容组成的频率电压转换电路，将脉冲信号的频率转换成电压信号，再将该电压信号输入到低通滤波电路中模拟乘法器MLT04的一端，通过该电压信号间接调节滤波器的截止频率，另一路待测信号也输入到低通滤波电路中模拟乘法器的另一端，从而实现了截止频率到输入频率的自动适应，可实现截止频率的范围为100Hz～10KHz。 The circuit design of the adaptive low-pass filter provided by the present invention is realized by utilizing the principle of frequency-voltage conversion and combining with an analog multiplier. First, the signal to be tested is divided into two channels, and one signal to be tested is input into the shaping circuit composed of NE555 to shape the signal to be tested, and the signal to be tested is transformed into a pulse signal, and then the pulse signal is input to the frequency-voltage converter composed of LM331 and resistors and capacitors. The circuit converts the frequency of the pulse signal into a voltage signal, and then inputs the voltage signal to one end of the analog multiplier MLT04 in the low-pass filter circuit, and indirectly adjusts the cut-off frequency of the filter through the voltage signal, and the other signal to be tested is also input To the other end of the analog multiplier in the low-pass filter circuit, so as to realize the automatic adaptation of the cut-off frequency to the input frequency, and the range of the cut-off frequency can be 100Hz ~ 10KHz.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110327498.9A CN102361437B (en) | 2011-10-25 | 2011-10-25 | Adaptive low pass filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110327498.9A CN102361437B (en) | 2011-10-25 | 2011-10-25 | Adaptive low pass filter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102361437A CN102361437A (en) | 2012-02-22 |
| CN102361437B true CN102361437B (en) | 2015-04-22 |
Family
ID=45586698
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201110327498.9A Expired - Fee Related CN102361437B (en) | 2011-10-25 | 2011-10-25 | Adaptive low pass filter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102361437B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103318256A (en) * | 2012-03-21 | 2013-09-25 | 昆达电脑科技(昆山)有限公司 | Wheel positioning and indicating device |
| CN104270121B (en) * | 2014-09-17 | 2017-10-20 | 四川九洲电器集团有限责任公司 | The frequency source device of Self Adaptive Control |
| CN105928613A (en) * | 2016-04-22 | 2016-09-07 | 西安西热节能技术有限公司 | Rotating machinery vibration signal oversampling filtering processing method |
| CN106788326B (en) * | 2017-02-07 | 2023-07-18 | 西北师范大学 | Frequency self-tracking 90° phase shifter |
| CN107765085A (en) * | 2017-11-15 | 2018-03-06 | 西北师范大学 | A kind of signal supervisory instrument and method |
| CN112019189A (en) * | 2020-09-10 | 2020-12-01 | 电子科技大学 | General design method of EMI filter for multiple modules of electric automobile |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101242164A (en) * | 2007-02-08 | 2008-08-13 | 联发科技（新加坡）私人有限公司 | Method and apparatus for tuning an active filter |
| CN201663585U (en) * | 2010-08-19 | 2010-12-01 | 西北师范大学 | Programmable Filter Based on Multiplier and Current Feedback Amplifier |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008017220A (en) * | 2006-07-06 | 2008-01-24 | Sony Corp | Charged main filter circuit |
-
2011
- 2011-10-25 CN CN201110327498.9A patent/CN102361437B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101242164A (en) * | 2007-02-08 | 2008-08-13 | 联发科技（新加坡）私人有限公司 | Method and apparatus for tuning an active filter |
| CN201663585U (en) * | 2010-08-19 | 2010-12-01 | 西北师范大学 | Programmable Filter Based on Multiplier and Current Feedback Amplifier |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102361437A (en) | 2012-02-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102361437B (en) | Adaptive low pass filter | |
| CN102751991B (en) | Delta-Sigma modulation principle based digital switching device and method for rotary transformer | |
| CN106610450B (en) | A kind of single-phase electric energy metering chip | |
| CN203606434U (en) | Impedance measurement circuit | |
| CN108318850A (en) | A kind of more acquisition channel testers of electronic mutual inductor and its method of calibration | |
| CN102466750A (en) | Alternating current measuring circuit and alternating current measuring method of digital multimeter | |
| CN104539264B (en) | Filtering method and filter circuit applied to EPS power-supply systems | |
| CN204758709U (en) | Multiplex's electric energy information acquisition device | |
| CN207869082U (en) | A kind of analog waveform generator | |
| CN207399155U (en) | Signal filtering process Compare System based on analog-digital converter | |
| CN202748160U (en) | Anti-interference temperature sampling circuit | |
| CN104391176A (en) | Software and hardware frequency measurement circuit compatible with electric power system signals | |
| CN205157646U (en) | Electric energy metering circuit based on voltage controlled oscillator | |
| CN107765085A (en) | A kind of signal supervisory instrument and method | |
| Yuan et al. | Research of zigbee and big data analysis based pulse monitoring system for efficient physical training | |
| CN203661012U (en) | Self-tracking second-order voltage-controlled multifunctional filter | |
| CN111830318B (en) | Wireless charging high-frequency current sampling system and sampling method thereof | |
| CN109782646A (en) | Multi-channel data synchronous | |
| CN205015397U (en) | Wireless frequency monitoring devices who charges | |
| CN103580646B (en) | A kind of method for estimating analog filter frequency response characteristic | |
| CN202931258U (en) | Biquad band-pass filter circuit and band pass filter | |
| CN202513879U (en) | Controllable frequency multiplier circuit | |
| CN204362012U (en) | Be applied to the filter circuit of EPS power-supply system | |
| CN113295917A (en) | Protection device sampling unit based on combination of Rogowski coil and LPCT | |
| CN206472117U (en) | Self-tracking 90° phase shifter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150422 Termination date: 20171025 |