KR900009969Y1 - Variable band filter - Google Patents

Variable band filter Download PDF

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Publication number
KR900009969Y1
KR900009969Y1 KR2019860016640U KR860016640U KR900009969Y1 KR 900009969 Y1 KR900009969 Y1 KR 900009969Y1 KR 2019860016640 U KR2019860016640 U KR 2019860016640U KR 860016640 U KR860016640 U KR 860016640U KR 900009969 Y1 KR900009969 Y1 KR 900009969Y1
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South Korea
Prior art keywords
amplifier
inverting
terminal
resistor
input terminal
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KR2019860016640U
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Korean (ko)
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KR880008843U (en
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권영기
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삼성정밀공업 주식회사
이동복
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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
    • H03H11/1204—Distributed RC filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/12—Bandpass or bandstop filters with adjustable bandwidth and fixed centre frequency

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  • Networks Using Active Elements (AREA)

Abstract

내용 없음.No content.

Description

가변대역필터Variable Band Filter

제1도는 인덕터를 사용한 종래의 가변대역필터 회로도.1 is a conventional variable band filter circuit diagram using an inductor.

제2도는 본 고안이 회로도이다.2 is a circuit diagram of the present invention.

* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings

R1, Rf : 가변저항 R2, R3 : 저항R1, Rf: variable resistor R2, R3: resistor

C1, C2 : 콘덴서 A1, A2 : OP앰프C1, C2: condenser A1, A2: OP amplifier

본 고안은 대역폭(Band width)과 공진주파수(Resonant Frequency)를 독립적으로 조절할 수 있는 가변대역 필터에 관한 것이다.The present invention relates to a variable band filter that can independently adjust the bandwidth (band width) and resonant frequency (Resonant Frequency).

종래의 대표적인 가변 대역필터로서는 제1도에 도시된 바와같은 구성을 가진 것이 안출된 바 있다.As a typical variable band pass filter, one having a configuration as shown in FIG. 1 has been devised.

제1도의 구성은, 입력단으로부터 OP앰프(A1)의 비반전단자(+)에 가변저항(R1)을 연결함과 동시에 상기의 OP앰프의 비반전단자(+)와 접지사이에 병렬로 콘덴서(C1)와 인덕터(L)를 연결하며, OP앰프(A1)의 반전 단자(-)를 이 OP앰프(A1)의 출력단자에 궤환접속함으로써 이루어진다.In FIG. 1, the variable resistor R1 is connected from the input terminal to the non-inverting terminal (+) of the OP amplifier A1, and at the same time, a capacitor (in parallel) is connected between the non-inverting terminal (+) of the OP amplifier and the ground. C1) and the inductor L are connected, and the inverting terminal (-) of the OP amplifier A1 is feedback-connected to the output terminal of the OP amplifier A1.

여기서, 입력단의 전압을 E1, 출력단의 전압을 E2라 하면, 이 가변대역필터의 전압에 대한 전달함수(Transfer function)는 다음과 같이 얻어진다.Here, assuming that the voltage at the input terminal is E1 and the voltage at the output terminal is E2, the transfer function for the voltage of the variable band pass filter is obtained as follows.

이때,이 된다.At this time, Becomes

여기서, 공진 주파수(f1)는 다음과 같다.Here, the resonance frequency f1 is as follows.

이고,이므로, 공진주파수(f1)는이 된다. ego, Therefore, the resonance frequency f1 is Becomes

또한, 대역폭(B)는 f1/Q인데, 이때 Q는 공진시의 회로의 Q factor로서,이므로,이 된다.In addition, the bandwidth B is f1 / Q, where Q is the Q factor of the circuit at resonance, Because of, Becomes

그러므로, 인덕터(L)을 조절함으로써 공진주파수(f1)를 조절하고, 저항(R1)을 조절함으로써 대역폭(B)를 조절할 수 있다. 그러나, 인덕터(L)를 사용하게 되면 튜닝이 매우 어려울 뿐만 아니라 온도에 대한 안정도도 떨어지는 단점이 있다.Therefore, the resonance frequency f1 may be adjusted by adjusting the inductor L, and the bandwidth B may be adjusted by adjusting the resistor R1. However, when using the inductor (L) is not only very difficult to tune, but also has a disadvantage of poor stability against temperature.

또한, 콘덴서(C1)를 가변시키면 공진주파수(f1)와 대역폭(B)가 동시에 변하게 되어 사용목적에 어긋난다.In addition, if the capacitor C1 is changed, the resonance frequency f1 and the bandwidth B are changed at the same time, which is not suitable for the purpose of use.

따라서 본 고안은 상기와 같은 문제점을 해소코저 안출한 것으로서, 가변대역필터에서 대역폭과 공진주파수를 독립적으로 조절하려할 때 튜닝을 쉽게 할 수 있고 온도에 대한 안정도가 좋은 회로를 제공하는 데 그 목적이 있다.Therefore, the present invention solves the above problems, and the objective of the present invention is to provide a circuit that is easy to tune and has a good temperature stability when trying to independently adjust the bandwidth and the resonant frequency in the variable band filter. have.

제2도는 본 고안의 회로도로서, 본 고안에서는 상기한 제1도의 회로에서 인덕터(L)를 제거하고, 이 인덕터 대신에 OP앰프(A2), 저항(R2), (R3), (Rf) 과 콘덴서(C2)로 구성되는 L등가회로를 구성한 점에 특징이 있다.FIG. 2 is a circuit diagram of the present invention, in which the inductor L is removed from the circuit of FIG. 1, and the op amps A2, resistors R2, R3, Rf and It is characterized in that the L equivalent circuit composed of the capacitor C2 is configured.

이를 상술하면, 입력신호(V1)가 가변저항(R1)을 거쳐 OP앰프(A1)의 비반전입력단(+)에 인가되고, OP앰프(A1)의 반전입력단(-)과 출력단자를 단락시킨 점(P)으로부터 출력신호(V2)가 나오고, 점(P)로부터 저항(R2)과 콘덴서(C2)를 거쳐 OP앰프(A2)의 반전입력단자(-)와 비반전입력단자(+)에 궤환신호가 각각 인가되고, 또한 OP앰프(A2)의 비반전입력단자(+)와 접지사이에 저항(R3)을 연결한다. 그리고 OP앰프(A2)의 출력단을 가변저항(Rf)를 경유하여 콘덴서(C1)와 가변저항(R1) 사이에 접속하여 OP앰프(A1)의 비반전입력단자(+)에 인가한다.Specifically, the input signal V1 is applied to the non-inverting input terminal (+) of the OP amplifier A1 via the variable resistor R1, and the short circuit of the inverting input terminal (-) and the output terminal of the OP amplifier A1 is shorted. The output signal V2 is output from the point P, from the point P through the resistor R2 and the capacitor C2 to the inverting input terminal (-) and the non-inverting input terminal (+) of the op amp A2. The feedback signals are respectively applied, and a resistor R 3 is connected between the non-inverting input terminal (+) of the OP amplifier A2 and the ground. The output terminal of the OP amplifier A2 is connected between the capacitor C1 and the variable resistor R1 via the variable resistor Rf and applied to the non-inverting input terminal (+) of the OP amplifier A1.

상기와 같은 구성을 가진 본 고안의 회로에서, 공진주파수와 대역폭은 전달함수(V2/V1)를 구해보면 쉽게 알 수 있다.In the circuit of the present invention having the configuration as described above, the resonance frequency and the bandwidth can be easily obtained by obtaining the transfer function (V2 / V1).

우선, R2=R3=R라 놓고 전달함수(V2/V1)를 구해보면First, let's set R2 = R3 = R and get the transfer function (V2 / V1).

이때이다. 결과적으로,At this time to be. As a result,

공진주파수(f2)는 Resonance frequency f2

Q 값은이므로,Q value is Because of,

대역폭(B')는이 된다.Bandwidth (B ') Becomes

상기의 식에서 알 수 있듯이, 대역폭(B')은 가변저항(R1)을 조절하여 가변할 수 있으며, 공진주파수(f2)는 대역폭(B')의 조절과는 독립적으로 가변저항(Rf)을 조절하여 가변할 수 있다.As can be seen from the above equation, the bandwidth B 'can be varied by adjusting the variable resistor R1, and the resonance frequency f2 adjusts the variable resistor Rf independently of the adjustment of the bandwidth B'. Can be varied.

상술한 바와 같이 동작하는 본 고안의 회로에 의하면, 인덕터를 사용하지 않고 가변저항을 사용하기 때문에 튜닝을 쉽게 할 수 있고 온도에 대한 안정도로 개선되는 이점이 있다.According to the circuit of the present invention operating as described above, since the variable resistor is used without using the inductor, the tuning can be easily performed and the stability with respect to temperature is improved.

Claims (1)

신호 입력단으로부터 OP앰프(A1)의 비반전단자(+)에 가변저항(R1)을 연결함과 동시에 OP앰프(A1)의 비반전단자(+)와 접지사이에 콘덴서(C1)를 연결하며, OP앰프(A1)의 반전단자(-)를 이 OP앰프(A1)의 출력단자에 접속하여 구성된 가변대역필터에 있어서, 상기한 OP앰프(A1)의 출력을 각각 저항(R2)과 콘덴서(C2)를 경유하여 OP앰프(A2)의 반전 및 비반전단자에 연결하고, OP앰프(A2)의 비반전입력단자(+)와 접지사이에 저항(R3)을 연결하는 한편 OP앰프(A2)의 출력을 가변저항(Rf)을 경유하여 상기한 OP앰프(A1)의 비반전입력단자(+)에 연결하여 구성되는 것을 특징으로 하는 가변대역필터.The variable resistor R1 is connected to the non-inverting terminal (+) of the OP amplifier A1 from the signal input terminal, and at the same time, the capacitor C1 is connected between the non-inverting terminal (+) of the OP amplifier A1 and ground. In the variable band filter configured by connecting the inverting terminal (-) of the OP amplifier A1 to the output terminal of the OP amplifier A1, the output of the above-described OP amplifier A1 is respectively applied to the resistor R2 and the capacitor C2. Connect to the inverting and non-inverting terminals of the OP amplifier A2 through), connect the resistor R3 between the non-inverting input terminal (+) of the OP amplifier A2 and ground, and A variable band pass filter comprising an output connected to a non-inverting input terminal (+) of the op amp A1 via a variable resistor Rf.
KR2019860016640U 1986-10-30 1986-10-30 Variable band filter KR900009969Y1 (en)

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KR2019860016640U KR900009969Y1 (en) 1986-10-30 1986-10-30 Variable band filter

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KR2019860016640U KR900009969Y1 (en) 1986-10-30 1986-10-30 Variable band filter

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KR880008843U KR880008843U (en) 1988-06-30
KR900009969Y1 true KR900009969Y1 (en) 1990-10-22

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