JPH0879013A - Switched capacitor band-pass filter for pilotsignal detection - Google Patents

Switched capacitor band-pass filter for pilotsignal detection

Info

Publication number
JPH0879013A
JPH0879013A JP7093907A JP9390795A JPH0879013A JP H0879013 A JPH0879013 A JP H0879013A JP 7093907 A JP7093907 A JP 7093907A JP 9390795 A JP9390795 A JP 9390795A JP H0879013 A JPH0879013 A JP H0879013A
Authority
JP
Japan
Prior art keywords
frequency
signal
filter
filter element
switched capacitor
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.)
Pending
Application number
JP7093907A
Other languages
Japanese (ja)
Inventor
Jeung-In Lee
廷仁 李
Yank-Gyun Kim
亮均 金
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Samsung Electronics Co Ltd
Original Assignee
Samsung Electronics Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Samsung Electronics Co Ltd filed Critical Samsung Electronics Co Ltd
Publication of JPH0879013A publication Critical patent/JPH0879013A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L7/00—Automatic control of frequency or phase; Synchronisation
    • H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
    • H03L7/08—Details of the phase-locked loop
    • H03L7/099—Details of the phase-locked loop concerning mainly the controlled oscillator of the loop
    • 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
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H17/00—Networks using digital techniques
    • H03H17/02—Frequency selective networks
    • H03H17/0248—Filters characterised by a particular frequency response or filtering method
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H19/00—Networks using time-varying elements, e.g. N-path filters
    • H03H19/004—Switched capacitor networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning
    • H03J3/02—Details
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L7/00—Automatic control of frequency or phase; Synchronisation
    • H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
    • H03L7/08—Details of the phase-locked loop
    • H03L7/0807—Details of the phase-locked loop concerning mainly a recovery circuit for the reference signal
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L7/00—Automatic control of frequency or phase; Synchronisation
    • H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
    • H03L7/08—Details of the phase-locked loop
    • H03L7/10—Details of the phase-locked loop for assuring initial synchronisation or for broadening the capture range
    • H03L7/107—Details of the phase-locked loop for assuring initial synchronisation or for broadening the capture range using a variable transfer function for the loop, e.g. low pass filter having a variable bandwidth
    • H03L7/1075—Details of the phase-locked loop for assuring initial synchronisation or for broadening the capture range using a variable transfer function for the loop, e.g. low pass filter having a variable bandwidth by changing characteristics of the loop filter, e.g. changing the gain, changing the bandwidth
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/44—Transmit/receive switching
    • H04B1/46—Transmit/receive switching by voice-frequency signals; by pilot signals

Abstract

PURPOSE: To make the pole frequency of a filter element precisely adjustable without requiring any clock signal impressed from the outside by providing a phase locked loop for impressing a clock signal having a specific frequency upon the clock signal of the filter element. CONSTITUTION: The free running frequency of the voltage-controlled oscillator 40 of a phase-locked loop 200 is set so that the frequency may become N (integer) times as high as the pole frequency of a filter element 100. The element 100 outputs a signal having a frequency f1 to the loop 200 by filtering input signals. The oscillator 40 outputs a signal having a frequency fVCO, which is N times as high as that of the input signals. The signal is impressed upon the clock signal of the element 100 and resets the pole frequency. The signal, in addition, is fed back to a phase detector 20 through a 1/N-frequency divider 10 and changes the oscillation frequency of the oscillator 40 in accordance with the frequency variation of the input signals.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、帯域通過フィルタに係
り、特に２キャリア音声多重放送受信機の放送状態識別
信号検出用のスイッチドキャパシタ帯域通過フィルタに
関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bandpass filter, and more particularly to a switched capacitor bandpass filter for detecting a broadcast state identification signal of a two-carrier audio multiplex broadcast receiver.

【０００２】[0002]

【従来の技術】２キャリア音声多重放送では副搬送波に
放送状態（モノ／ステレオ／二カ国語(bilingual) ）を
表示する放送状態識別信号、すなわちパイロット信号を
載せて放送する。したがって、テレビジョン又はビデオ
テープレコーダなどではパイロット信号を検出して放送
状態を判別する。ところが、パイロット信号は音声信号
に比べて大きさが非常に小さいので、音声信号や各種の
雑音により激しく歪曲される。それで、パイロット信号
を検出するためには、通過帯域の狭い帯域通過フィルタ
が必要である。2. Description of the Related Art In two-carrier audio multiplex broadcasting, a broadcast status identification signal indicating a broadcast status (mono / stereo / bilingual), that is, a pilot signal is mounted on a subcarrier for broadcasting. Therefore, a television or video tape recorder or the like detects the pilot signal to determine the broadcast state. However, since the pilot signal is much smaller than the voice signal, it is severely distorted by the voice signal and various noises. Therefore, in order to detect the pilot signal, a band pass filter having a narrow pass band is necessary.

【０００３】通過帯域の狭いスイッチドキャパシタ帯域
通過フィルタを具現するには下記のような３つの方法が
ある。There are the following three methods for implementing a switched capacitor bandpass filter having a narrow passband.

【０００４】第１に、動作相互コンダクタンス増幅器
（ＯＴＡ：Operational Transconductance Amplifier）
を利用する方法である。該方法はフィルタを内蔵するこ
とにより、外部部品数と集積回路（ＩＣ：Integrated C
ircuit）の端子数を減らす。これはコストを低められる
ようにする。しかしながら、動作相互コンダクタンス増
幅器フィルタの極点は集積回路の内部抵抗およびキャパ
シターの絶対値により決定され、その絶対値は工程変数
に応じて変換するので、実際の集積回路で製作する場
合、工程変数の影響のために正確な極点を有するフィル
タは具現され得ない。First, an operational transconductance amplifier (OTA).
Is the method of using. In this method, the number of external parts and the integrated circuit (IC: Integrated C
ircuit) to reduce the number of terminals. This allows costs to be reduced. However, the pole of the operating transconductance amplifier filter is determined by the absolute value of the internal resistance and capacitor of the integrated circuit, and the absolute value is converted according to the process variable. Because of this, a filter with exact poles cannot be implemented.

【０００５】第２に、スイッチドキャパシタフィルタ
（ＳＣＦ:Switched Capacitor Filter) を利用する方法
である。該方法においてキャパシタフィルタの極点は、
キャパシタの絶対値とは関係なくキャパシタの比とスイ
ッチを駆動するために印加されるクロックの周波数によ
ってのみ決定される。したがって、集積回路でフィルタ
を製作する時に、工程変数によりキャパシタの絶対値が
変化してもキャパシタの相対的な比はほぼ変化しないの
で、正確が特性が得られる。反面、スイッチドキャパシ
タフィルタは正確なクロック信号を要するので、高価の
部品を使用して外部からクロック信号を印加せねばなら
ない。図１にスイッチドキャパシタフィルタを利用した
従来の帯域通過フィルタの構成を示した。The second method is to use a switched capacitor filter (SCF). In this method, the pole of the capacitor filter is
It is determined only by the ratio of the capacitors and the frequency of the clock applied to drive the switch, regardless of the absolute value of the capacitors. Therefore, when manufacturing a filter with an integrated circuit, even if the absolute value of the capacitor changes depending on the process variable, the relative ratio of the capacitor does not substantially change, so that accurate characteristics can be obtained. On the other hand, since the switched capacitor filter requires an accurate clock signal, it is necessary to apply an external clock signal using expensive parts. FIG. 1 shows the configuration of a conventional bandpass filter using a switched capacitor filter.

【０００６】第３に、外部フィルタを使用する方法であ
る。単品で販売されるフィルタを使用すれば、特性上前
記の方法に比べて著しく優れるが、単品フィルタが高価
の部品なので、コストが高くなる短所がある。Thirdly, there is a method of using an external filter. If a filter that is sold as a single item is used, it is remarkably superior to the above method in terms of characteristics, but since the single item filter is an expensive component, the cost is high.

【０００７】[0007]

【発明が解決しようとする課題】前記の問題点を解決す
るために本発明の目的は、外部から印加されるクロック
信号なく極点を正確に調整できるスイッチドキャパシタ
帯域通過フィルタを提供することである。SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an object of the present invention is to provide a switched capacitor band pass filter capable of accurately adjusting the poles without an externally applied clock signal. .

【０００８】[0008]

【課題を解決するための手段】上記目的を達成するため
の本発明は、フィルタ要素と、前記フィルタ要素の出力
信号を入力し、前記フィルタ要素の極点周波数の整数倍
となる周波数を有するクロック信号を前記フィルタ要素
のクロック信号に印加するための位相同期ループと、を
備えることを特徴とするスイッチドキャパシタ帯域通過
フィルタである。In order to achieve the above object, the present invention provides a clock signal having a frequency that is an integer multiple of the pole frequency of the filter element and that receives the output signal of the filter element. And a phase-locked loop for applying to the clock signal of the filter element.

【０００９】又、本発明のスイッチドキャパシタ帯域通
過フィルタにおいて、前記位相同期ループは、前記フィ
ルタ要素の出力信号を入力して位相を検出するための位
相検出手段と、前記位相検出手段の出力信号を低域通過
フィルタリングするための低域通過フィルタと、前記低
域通過フィルタの出力信号に応答して周波数を可変する
ための電圧制御発振器と、前記電圧制御発振器の出力信
号を入力して１／Ｎ倍に分周して前記位相検出手段に印
加するための１／Ｎ分周器と、を備えることを特徴とす
る又、本発明の前記スイッチドキャパシタ帯域通過フィ
ルタは限定された周波数帯域内の複数個の入力信号のう
ち最も大きい信号を検出することを特徴とする。In the switched-capacitor bandpass filter of the present invention, the phase-locked loop receives the output signal of the filter element to detect the phase, and the output signal of the phase detection means. A low-pass filter for low-pass filtering, a voltage-controlled oscillator for varying the frequency in response to the output signal of the low-pass filter, and an input signal of the voltage-controlled oscillator And a 1 / N frequency divider for dividing the frequency by N and applying it to the phase detecting means. Further, the switched capacitor bandpass filter of the present invention is within a limited frequency band. Is detected among the plurality of input signals of.

【００１０】又、本発明の前記スイッチドキャパシタ帯
域通過フィルタは限定された周波数帯域内の複数個の入
力信号のうち最も先に入力される信号を検出することを
特徴とする。Further, the switched capacitor bandpass filter of the present invention is characterized by detecting the earliest input signal among a plurality of input signals within a limited frequency band.

【００１１】[0011]

【作用】上述のように構成された請求項１〜４記載の本
発明は、外部クロックを必要としないフィルタ要素を使
用することにより、工程変数によるエラーを自体調整を
通じて除去することができる。According to the present invention constructed as described above, it is possible to eliminate an error due to a process variable through self-adjustment by using a filter element which does not require an external clock.

【００１２】[0012]

【実施例】以下、添付した図面に基づき本発明の実施例
を詳細に説明する。Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

【００１３】図２は本発明のスイッチドキャパシタを利
用した帯域通過フィルタのブロック図である。FIG. 2 is a block diagram of a bandpass filter using the switched capacitor of the present invention.

【００１４】図２において、スイッチドキャパシタ帯域
通過フィルタは、フィルタ要素１００および位相同期ル
ープ２００からなる。In FIG. 2, the switched capacitor bandpass filter comprises a filter element 100 and a phase locked loop 200.

【００１５】位相同期ループ２００は、１／Ｎ分周器１
０，位相検出器２０，低域通過フィルタ３０および電圧
制御発振器４０からなる。The phase locked loop 200 includes a 1 / N frequency divider 1
0, a phase detector 20, a low pass filter 30 and a voltage controlled oscillator 40.

【００１６】位相同期ループ２００の電圧制御発振器４
０は、入力信号の周波数と同一の周波数を発振させ、電
圧制御発振器４０の出力信号はフィルタ要素１００のク
ロック信号として使用する。Voltage controlled oscillator 4 of phase locked loop 200
0 oscillates the same frequency as the frequency of the input signal, and the output signal of the voltage controlled oscillator 40 is used as the clock signal of the filter element 100.

【００１７】図３は図２に示したフィルタ要素の回路図
である。図３において、フィルタ要素１００は比較器
１，２、キャパシタＣ１，Ｃ２，Ｃ３，Ｃ４，Ｃ５，Ｃ
６およびクロック信号ＣＫと反転クロック信号ＣＫＢに
より制御される数個のスイッチからなる。FIG. 3 is a circuit diagram of the filter element shown in FIG. In FIG. 3, the filter element 100 includes comparators 1 and 2, capacitors C1, C2, C3, C4, C5 and C.
6 and several switches controlled by the clock signal CK and the inverted clock signal CKB.

【００１８】図３に示したフィルタ要素の伝達関数、す
なわちＨ（Ｓ）は次の式（１）の通りである。The transfer function of the filter element shown in FIG. 3, that is, H (S) is given by the following equation (1).

【００１９】[0019]

【数１】 [Equation 1]

【００２０】前記式（１）からフィルタ要素の極点ｆC
を求めると、下記の式（２）の通りである。From the above equation (1), the pole point f C of the filter element
The following equation (2) is obtained.

【００２１】[0021]

【数２】 [Equation 2]

【００２２】前記式でαはフィルタ要素の定数（２次帯
域通過フィルタの場合、この定数は１／２πである）。
ｆCKはフィルタ要素のクロック周波数、ルート値はフィ
ルタ要素のキャパシタ比をそれぞれ示す。In the above equation, α is a constant of the filter element (in the case of a second-order bandpass filter, this constant is 1 / 2π).
f CK indicates the clock frequency of the filter element, and the root value indicates the capacitor ratio of the filter element.

【００２３】前記式（２）から分かるように、フィルタ
要素の極点は、キャパシタの比とクロック周波数ｆCKに
よって決定される。キャパシタの比が一定する場合は、
極点はクロック周波数に比例する値を有する。それで、
クロック周波数ｆCKがフィルタ要素の極点の整数倍Ｎと
なるように、キャパシタの比を決定する。そして、電圧
制御発振器のフリーランニング周波数ｆf がこのクロッ
ク周波数と同様であるように設定する。電圧制御発振器
の出力周波数ｆvco を１／Ｎ分周器１０により１／Ｎ分
周して位相検出器２０に帰還させれば、１／Ｎ分周器１
０の出力周波数ｆ2 は、位相同期ループ２００がロッキ
ング状態にある場合、位相検出器２０に入力される信号
の周波数ｆ1 と同様である。位相同期ループの周波数範
囲はシステムの誤動作を最小化するために出来る限り狭
く設定する。As can be seen from the equation (2), the pole point of the filter element is determined by the ratio of the capacitors and the clock frequency f CK . If the ratio of capacitors is constant,
The pole has a value proportional to the clock frequency. So
The capacitor ratio is determined so that the clock frequency f CK is an integral multiple N of the pole of the filter element. Then, the free running frequency f f of the voltage controlled oscillator is set to be similar to this clock frequency. If the output frequency f vco of the voltage controlled oscillator is divided by 1 / N by the 1 / N divider 10 and fed back to the phase detector 20, the 1 / N divider 1
The output frequency f 2 of 0 is similar to the frequency f 1 of the signal input to the phase detector 20 when the phase locked loop 200 is in the locking state. The frequency range of the phase locked loop should be set as narrow as possible to minimize malfunction of the system.

【００２４】本発明のスイッチドキャパシタ帯域通過フ
ィルタの動作を調べると、次の通りである。The operation of the switched capacitor bandpass filter of the present invention is examined as follows.

【００２５】初期状態、すなわち無入力時には電圧制御
発振器４０はフリーランニング状態にある。そして、フ
ィルタ要素の極点ｆC は電圧制御発振器４０のフリーラ
ンニング周波数ｆf によって決定される。フィルタ要素
に位相同期ループ２００の捕捉周波数範囲内に属する周
波数を有する入力信号が印加されれば、フィルタ要素１
００はこの信号をフィルタリングして周波数ｆ1 を有す
る信号を位相同期ループ２００に出力し、位相同期ルー
プ２００の電圧制御発振器４０はフィルタ要素の出力信
号に相応する周波数の信号、すなわち入力信号のＮ倍の
周波数を有する信号ｆvco を発振させる。ｆvco はフィ
ルタ要素１００のクロックに印加され周波数ｆC を再設
定し、又位相検出器２０に帰還され位相同期ループ２０
０はロッキング状態となる。位相同期ループ２００がロ
ッキング状態の間には入力信号の周波数の変化に応じて
電圧制御発振器４０の発振周波数が変わる。この時、フ
ィルタ要素１００の周波数ｆC もそれに応じて変化す
る。入力される信号の周波数が位相同期ループ２００の
ロッキング周波数範囲を逸すると、位相同期ループ２０
０はロッキング状態が解除され、電圧制御発振器４０は
フリーランニング状態となり周波数ｆC は初期状態に戻
る。In the initial state, that is, when there is no input, the voltage controlled oscillator 40 is in a free running state. The pole point f C of the filter element is determined by the free running frequency f f of the voltage controlled oscillator 40. If an input signal having a frequency within the acquisition frequency range of the phase locked loop 200 is applied to the filter element, the filter element 1
00 filters this signal and outputs a signal having a frequency f 1 to the phase-locked loop 200, and the voltage-controlled oscillator 40 of the phase-locked loop 200 outputs a signal having a frequency corresponding to the output signal of the filter element, that is, N of the input signal. It oscillates a signal f vco having a doubled frequency. f vco is applied to the clock of the filter element 100 to reset the frequency f C , and is also fed back to the phase detector 20 to provide the phase locked loop 20.
0 is the locking state. While the phase locked loop 200 is in the locking state, the oscillation frequency of the voltage controlled oscillator 40 changes according to the change of the frequency of the input signal. At this time, the frequency f C of the filter element 100 also changes accordingly. When the frequency of the input signal falls outside the locking frequency range of the phase locked loop 200, the phase locked loop 20
In 0, the locked state is released, the voltage controlled oscillator 40 becomes a free running state, and the frequency f C returns to the initial state.

【００２６】図２に示した回路は、集積化する場合に工
程変数の影響のために、電圧制御発振器４０のフリーラ
ンニング周波数ｆf はΔｆf ほど変化されることができ
る。すなわち、初期状態にフィルタ要素の極点も元々目
標とした周波数ｆC からｆC＋ΔｆC （又はｆC −Δｆ
C ）に変化され得る。この状態でフィルタに入力が印加
されれば、極点が設定した位置から逸しているので、通
過させようとする信号も減衰して位相同期ループ２００
に出力される。該減衰された信号の大きさが位相同期ル
ープ２００の位相検出器２０を駆動させ得る範囲内にあ
れば、位相同期ループ２００は動作してロッキング状態
となる。電圧制御発振器４０はこれに該当する周波数の
信号を発振させる。該電圧制御発振器４０の出力信号ｆ
vco がフィルタ要素を駆動して、フィルター要素の極点
はｆC ＋ΔｆC （又はｆC −ΔｆC ）から元々目標とし
た周波数であるｆC に移動する。すなわち、工程変数に
よってフィルタ要素の極点が変化しても全体システムは
自体調整を通じて正確な特性を示す。図４に図２に示し
た帯域通過フィルタの特性グラフを示す。When the circuit shown in FIG. 2 is integrated, the free running frequency f f of the voltage controlled oscillator 40 can be changed by Δf f due to the influence of process variables. That is, in the initial state, the pole of the filter element is originally set to the target frequency f C to f C + Δf C (or f C −Δf
C ) can be changed. If an input is applied to the filter in this state, the pole is out of the set position, so that the signal to be passed is also attenuated and the phase locked loop 200
Is output to If the magnitude of the attenuated signal is within the range that can drive the phase detector 20 of the phase locked loop 200, the phase locked loop 200 operates and enters the locking state. The voltage controlled oscillator 40 oscillates a signal having a frequency corresponding to this. Output signal f of the voltage controlled oscillator 40
The vco drives the filter element and the pole of the filter element moves from f C + Δf C (or f C −Δf C ) to f C , which is the originally targeted frequency. That is, even if the pole of the filter element changes depending on the process variable, the entire system shows accurate characteristics through its own adjustment. FIG. 4 shows a characteristic graph of the bandpass filter shown in FIG.

【００２７】[0027]

【発明の効果】以上説明したように、請求項１〜４記載
の本発明の帯域通過フィルタは、外部クロックを必要と
しないフィルタ要素を利用した帯域通過フィルタにより
自体調整を通じて工程変数によるエラーを除去すること
ができる。また、位相同期ループの周波数範囲内に存在
する数個の信号が入力される場合には入力信号のうちで
最も大きい信号、あるいは最も先に入力される信号を追
跡する。As described above, the band pass filter of the present invention according to claims 1 to 4 eliminates errors due to process variables through its own adjustment by a band pass filter using a filter element that does not require an external clock. can do. Further, when several signals existing in the frequency range of the phase locked loop are input, the largest signal among the input signals or the earliest input signal is traced.

【図面の簡単な説明】[Brief description of drawings]

【図１】 従来のスイッチドキャパシタ帯域通過フィル
タのブロック図である。FIG. 1 is a block diagram of a conventional switched capacitor bandpass filter.

【図２】 本発明のスイッチドキャパシタ帯域通過フィ
ルタのブロック図である。FIG. 2 is a block diagram of a switched capacitor bandpass filter of the present invention.

【図３】 図２に示したフィルタ要素の回路図である。FIG. 3 is a circuit diagram of the filter element shown in FIG.

【図４】 図２に示したスイッチドキャパシタ帯域通過
フィルタの周波数対利得の関係を示すグラフである。FIG. 4 is a graph showing a frequency vs. gain relationship of the switched capacitor bandpass filter shown in FIG.

【符号の説明】[Explanation of symbols]

１０ １／Ｎ分周器 ２０ 位相検出器 ３０ 低域通過フィルタ ４０ 電圧制御発振器 １００ フィルタ要素 ２００ 位相同期ループ 10 1 / N frequency divider 20 Phase detector 30 Low pass filter 40 Voltage controlled oscillator 100 Filter element 200 Phase locked loop

Claims (4)

【特許請求の範囲】[Claims] 【請求項１】 フィルタ要素と、 前記フィルタ要素の出力信号を入力し、前記フィルタ要
素の極点周波数の整数倍となる周波数を有するクロック
信号を前記フィルタ要素のクロック信号に印加するため
の位相同期ループと、を備えることを特徴とするスイッ
チドキャパシタ帯域通過フィルタ。1. A phase locked loop for inputting a filter element and an output signal of the filter element, and applying a clock signal having a frequency that is an integer multiple of a pole frequency of the filter element to the clock signal of the filter element. And a switched capacitor bandpass filter. 【請求項２】 前記位相同期ループは、 前記フィルタ要素の出力信号を入力して位相を検出する
ための位相検出手段と、 前記位相検出手段の出力信号を低域通過フィルタリング
するための低域通過フィルタと、 前記低域通過フィルタの出力信号に応答して周波数を可
変するための電圧制御発振器と、 前記電圧制御発振器の出力信号を入力して１／Ｎ倍に分
周して前記位相検出手段に印加するための１／Ｎ分周器
と、を備えることを特徴とする請求項１に記載のスイッ
チドキャパシタ帯域通過フィルタ。2. The phase-locked loop includes phase detection means for inputting an output signal of the filter element to detect a phase, and low-pass filtering for low-pass filtering the output signal of the phase detection means. A filter, a voltage-controlled oscillator for varying the frequency in response to the output signal of the low-pass filter, and an input signal of the output signal of the voltage-controlled oscillator to divide the frequency by 1 / N to obtain the phase detection means And a 1 / N divider for applying to the switched capacitor bandpass filter according to claim 1. 【請求項３】 前記スイッチドキャパシタ帯域通過フィ
ルタは限定された周波数帯域内の複数個の入力信号のう
ち最も大きい信号を検出することを特徴とする請求項１
に記載のスイッチドキャパシタ帯域通過フィルタ。3. The switched capacitor bandpass filter detects the largest signal among a plurality of input signals within a limited frequency band.
A switched capacitor bandpass filter according to. 【請求項４】 前記スイッチドキャパシタ帯域通過フィ
ルタは限定された周波数帯域内の複数個の入力信号のう
ち最も先に入力される信号を検出することを特徴とする
請求項１に記載のスイッチドキャパシタ帯域通過フィル
タ。4. The switched capacitor band pass filter according to claim 1, wherein the switched capacitor band pass filter detects the earliest input signal among a plurality of input signals in a limited frequency band. Capacitor band pass filter.
JP7093907A 1994-08-12 1995-04-19 Switched capacitor band-pass filter for pilotsignal detection Pending JPH0879013A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR94P19947 1994-08-12
KR1019940019947A KR970001313B1 (en) 1994-08-12 1994-08-12 Switched capacitor filter

Publications (1)

Publication Number Publication Date
JPH0879013A true JPH0879013A (en) 1996-03-22

Family

ID=19390287

Family Applications (1)

Application Number Title Priority Date Filing Date
JP7093907A Pending JPH0879013A (en) 1994-08-12 1995-04-19 Switched capacitor band-pass filter for pilotsignal detection

Country Status (4)

Country Link
JP (1) JPH0879013A (en)
KR (1) KR970001313B1 (en)
CN (1) CN1057176C (en)
DE (1) DE19512858A1 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100450658B1 (en) * 1997-08-27 2004-11-16 삼성전자주식회사 Apparatus and method for controlling switched capacitor filter, especially controlling switched capacitor filter by reference clock signal
US7403063B2 (en) * 2005-11-23 2008-07-22 Mediatek Inc. Apparatus and method for tuning center frequency of a filter
DE102006034581A1 (en) * 2006-07-26 2008-01-31 Infineon Technologies Ag Filter device i.e. second order phase locked loop filter, has switched capacitor circuit arranged between input and output of operational amplifier, where capacitor circuit comprises capacitor and switching device
CN102098044A (en) * 2010-12-10 2011-06-15 青岛海信信芯科技有限公司 Pixel phase lock clock frequency generating method and device
JP5638419B2 (en) 2011-02-25 2014-12-10 セイコーエプソン株式会社 Signal processing circuit, physical quantity detection device, angular velocity detection device, integrated circuit device, and electronic apparatus
CN104935290B (en) * 2015-07-01 2017-07-28 东南大学 The SCF and preparation method of silicon substrate low-leakage current clamped beam grid
CN111142058B (en) * 2020-01-02 2022-05-17 联芸科技（杭州）有限公司 Resistance detection device and method

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL8603249A (en) * 1986-12-22 1988-07-18 Philips Nv Apparatus for decoding a stereo multiplex signal.
US4932058A (en) * 1989-08-14 1990-06-05 Delco Electronics Corporation Pilot cancellation circuit

Also Published As

Publication number Publication date
KR970001313B1 (en) 1997-02-05
CN1057176C (en) 2000-10-04
KR960009394A (en) 1996-03-22
DE19512858A1 (en) 1996-02-15
CN1117667A (en) 1996-02-28

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