KR20070027346A - Circuit for adjusting crystal frequency deviation - Google Patents

Circuit for adjusting crystal frequency deviation Download PDF

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Publication number
KR20070027346A
KR20070027346A KR1020050082836A KR20050082836A KR20070027346A KR 20070027346 A KR20070027346 A KR 20070027346A KR 1020050082836 A KR1020050082836 A KR 1020050082836A KR 20050082836 A KR20050082836 A KR 20050082836A KR 20070027346 A KR20070027346 A KR 20070027346A
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South Korea
Prior art keywords
frequency
crystal
deviation
frequency deviation
capacitor
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KR1020050082836A
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Korean (ko)
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안승광
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엘지이노텍 주식회사
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Priority to KR1020050082836A priority Critical patent/KR20070027346A/en
Publication of KR20070027346A publication Critical patent/KR20070027346A/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
    • H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
    • H03J7/02—Automatic frequency control
    • H03J7/04—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
    • H03J7/08—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant using varactors, i.e. voltage variable reactive diodes
    • 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

Abstract

A crystal for adjusting a crystal frequency deviation is provided to remove a frequency deviation between tuners by removing a deviation of a crystal frequency based on a variable capacitor for frequency compensation. A crystal for adjusting a crystal frequency deviation includes an MOPLL(Mixer Oscillator Phase Locked Loop) IC(10), a crystal(20), a load capacitor(30), and a variable capacitance capacitor for frequency compensation(40). The MOPLL IC(10) provides a local oscillation frequency. The crystal(20) is connected to the MOPLL IC(10), and provides a source frequency. The load capacitor(30) is connected between the crystal(20) and a ground. The variable capacitance capacitor for frequency compensation(40) is connected to the load capacitor(30) in parallel to adjust a frequency deviation of the crystal(20). The frequency deviation of the crystal(20) is set to Œ10Hz, and the variable capacitance capacitor for frequency compensation(40) is changed in the range of 0 to 40 pF.

Description

크리스탈 주파수 편차 조정회로{CIRCUIT FOR ADJUSTING CRYSTAL FREQUENCY DEVIATION}Crystal Frequency Deviation Control Circuit {CIRCUIT FOR ADJUSTING CRYSTAL FREQUENCY DEVIATION}

도 1은 종래의 크리스탈 주파수 편차 조정회로를 보여준다.1 shows a conventional crystal frequency deviation adjustment circuit.

도 2는 본 발명에 따른 크리스탈 주파수 편차 조정회로를 보여준다.2 shows a crystal frequency deviation adjustment circuit according to the present invention.

본 발명은 크리스탈 주파수 편차 조정회로에 관한 것이다.The present invention relates to a crystal frequency deviation adjusting circuit.

일반적으로, 튜너에 있어서 주파수 변환을 위해 MOPLL IC는 국부 발진주파수를 믹서에 기준 주파수원으로 제공한다. 이때, MOPLL IC의 국부 발진주파수의 소스로 크리스탈이 주로 이용된다.In general, for frequency conversion in the tuner, the MOPLL IC provides the local oscillation frequency as a reference frequency source to the mixer. At this time, the crystal is mainly used as a source of the local oscillation frequency of the MOPLL IC.

크리스탈로 발생되는 주파수는 자체의 물성이나 사용환경 등에 관련되어 일정한 주파수 편차를 갖는다. The frequency generated by the crystal has a certain frequency deviation related to its physical properties and usage environment.

이러한 주파수 편차를 균일하게 조정하기 위하여 통상 로드 캐패시터(load capacitor)가 이용된다.In order to uniformly adjust this frequency deviation, a load capacitor is usually used.

도 1은 종래의 크리스탈 주파수 편차 조정회로를 보여준다.1 shows a conventional crystal frequency deviation adjustment circuit.

MOPLL IC(10)에 소스 주파수를 제공하는 크리스탈(20)의 주파수 편차를 조정하기 위하여 로드 캐패시터(30)를 크리스탈(20)과 접지 사이에 연결한다.The load capacitor 30 is connected between the crystal 20 and ground to adjust the frequency deviation of the crystal 20 providing the source frequency to the MOPLL IC 10.

일반적으로 튜너에 이용되는 4㎒ 크리스탈(20)은 ±120㎐의 주파수 편차를 갖기 때문에 최대 240㎐가 변화한다. 이에 따라 튜너의 국부 발진주파수가 800㎒인 경우에는 48㎑가 변화하기 때문에 크리스탈(20) 간의 편차는 1㎐에서 48㎑의 범위에 이르러 결과적으로 튜너 간의 편차가 심해진다.In general, since the 4 MHz crystal 20 used in the tuner has a frequency deviation of ± 120 kHz, the maximum 240 kHz varies. As a result, when the local oscillation frequency of the tuner is 800 MHz, the 48 kHz changes, so that the variation between the crystals 20 is in the range of 1 kHz to 48 kHz, resulting in a severe deviation between the tuners.

이 경우, 국부 발진주파수와 입력되는 방해파가 혼합되어 화면상에 비트(beat)가 발생하게 된다.In this case, the local oscillation frequency and the interference wave input are mixed to generate a beat on the screen.

그러나, 도 1과 같이 고정값을 갖는 로드 캐패시터로는 이러한 주파수 편차를 제거할 수 없다는 문제점이 있다.However, there is a problem that such a frequency deviation cannot be eliminated with a load capacitor having a fixed value as shown in FIG. 1.

따라서, 본 발명은 이러한 종래의 문제점을 해결하기 위하여 제시되는 것으로, 크리스털 간의 주파수 편차를 제거하여 화면상에 비트가 발생하지 않도록 하는데 그 목적이 있다.Accordingly, the present invention has been proposed to solve this conventional problem, and an object thereof is to remove frequency deviation between crystals so that no bit occurs on the screen.

본 발명의 다른 목적과 특징 및 이점은 이하에 설명되는 실시예로부터 보다 명확하게 이해될 것이다.Other objects, features and advantages of the present invention will be more clearly understood from the embodiments described below.

본 발명에 따르면, 국부 발진주파수를 제공하는 MOPLL IC와, MOPLL IC에 연결되어 소스 주파수를 제공하는 크리스탈, 및 크리스털과 접지 사이에 연결된 로드 캐패시터를 포함하는 튜너에서, 크리스탈의 주파수 편차를 조정하기 위하여 주파수 보상용 가변용량 캐패시터를 로드 캐패시터와 병렬로 연결하는 크리스탈 주파수 편차 조정회로가 개시된다.According to the invention, in a tuner comprising a MOPLL IC providing a local oscillation frequency, a crystal connected to the MOPLL IC to provide a source frequency, and a load capacitor connected between the crystal and ground, to adjust the frequency deviation of the crystal; Disclosed is a crystal frequency deviation adjustment circuit that connects a variable capacitance capacitor for frequency compensation in parallel with a load capacitor.

바람직하게, 크리스탈의 주파수 편차는 ± 10㎐로 설정되고, 주파수 보상용 가변용량 캐패시터는 0 내지 40㎊ 범위 내에서 변화될 수 있다.Preferably, the frequency deviation of the crystal is set to ± 10 Hz, and the variable capacitance capacitor for frequency compensation may vary within a range of 0 to 40 Hz.

이하, 첨부된 발명을 참조하여 본 발명의 일 실시예를 설명한다.Hereinafter, with reference to the accompanying invention will be described an embodiment of the present invention.

도 2는 본 발명에 따른 크리스탈 주파수 편차 조정회로를 보여준다.2 shows a crystal frequency deviation adjustment circuit according to the present invention.

도시된 바와 같이, MOPLL IC(10)에 소스 주파수를 제공하는 크리스탈(20)의 주파수 편차를 조정하기 위하여 주파수 보상용 가변용량 캐패시터(40)를 로드 캐패시터(30)와 병렬로 연결한다.As shown, the frequency compensation variable capacitance capacitor 40 is connected in parallel with the load capacitor 30 to adjust the frequency deviation of the crystal 20 that provides the source frequency to the MOPLL IC 10.

일 예로, 로드 캐패시터(30)는 5㎊ 내지 20㎊ 중의 하나가 이용될 수 있고, 주파수 보상용 가변용량 캐패시터(40)는 0 내지 40㎊ 범위 내에서 변화될 수 있다.For example, the load capacitor 30 may be one of 5 kHz to 20 kHz, and the variable capacitance capacitor 40 for frequency compensation may vary within a range of 0 to 40 kHz.

이와 같은 구성의 크리스탈 주파수 편차 조정회로의 동작을 설명한다.The operation of the crystal frequency deviation adjusting circuit having such a configuration will be described.

주파수 보상용 가변용량 캐패시터(40)가 10㎊이 변할 경우, 크리스탈 주파수는 10㎐ 변화하고, 주파수 보상용 가변용량 캐패시터(40)가 40㎊이 변할 경우, 크리스탈 주파수는 40㎐ 변화한다.When the frequency compensation variable capacitance capacitor 40 changes by 10 Hz, the crystal frequency changes by 10 Hz. When the frequency compensation variable capacitor capacitor 40 changes by 40 Hz, the crystal frequency changes by 40 Hz.

따라서, 목표로 하는 크리스탈 주파수의 편차를 4㎒±10㎐로 설정하였다면, 크리스탈 주파수의 편차가 0인 경우를 기준으로 주파수 보상용 가변용량 캐패시터(40)의 용량을 20㎊으로 설정한다. Therefore, if the deviation of the target crystal frequency is set to 4 MHz +/- 10 Hz, the capacitance of the variable capacity capacitor 40 for frequency compensation is set to 20 Hz on the basis that the deviation of the crystal frequency is zero.

이후, 예를 들어, 크리스탈 주파수가 + 10㎐의 편차가 발생하였다고 하면, 주파수 보상용 가변용량 캐패시터(40)의 용량을 현재 설정된 용량 20㎊에서 -10㎊ 만큼 줄여 발생된 주파수 편차를 제거한다.Subsequently, for example, if the crystal frequency has a deviation of +10 Hz, the capacitance of the variable capacitance capacitor 40 for frequency compensation is reduced by -10 Hz from the currently set capacitance of 20 Hz to remove the generated frequency deviation.

다수개의 크리스탈이 있는 경우에는 상기한 방법을 각 크리스탈에 대해 순차적으로 반복함으로써 크리스탈 간의 주파수 편차를 제거할 수 있으며, 결과적으로 튜너간의 주파수 편차를 제거할 수 있다. When there are a plurality of crystals, the above-described method can be repeated for each crystal in order to remove the frequency deviation between the crystals, and as a result, the frequency deviation between the tuners can be eliminated.

또한, 국부 발진주파수와 입력되는 방해파가 혼합되어 화면상에 나타나는 비트(beat)를 제거할 수 있다. In addition, the local oscillation frequency and the incoming interference wave may be mixed to remove the beat appearing on the screen.

이상에서는 본 발명의 바람직한 실시예에 대하여 설명하였으나, 당업자의 레벨에서 다양한 변경과 변형을 가할 수 있으며, 이러한 변경과 변형은 본 발명의 범주를 벗어나지 않는 한, 본 발명에 속하는 것으로 해석되어야 한다.In the above description of the preferred embodiment of the present invention, various changes and modifications can be made at the level of those skilled in the art, and such changes and modifications should be construed as belonging to the present invention without departing from the scope of the present invention.

이상에서 설명한 바와 같이, 주파수 보상용 가변용량 캐패시터를 이용하여 크리스탈 주파수의 편차를 제거함으로써 크리스탈 간의 주파수 편차를 제거할 수 있으며, 결과적으로 튜너간의 주파수 편차를 제거할 수 있다는 이점이 있다. As described above, the frequency deviation between the crystals can be removed by removing the deviation of the crystal frequency by using the variable capacitance capacitor for frequency compensation, and as a result, there is an advantage that the frequency deviation between the tuners can be removed.

이에 따라, 국부 발진주파수와 입력되는 방해파가 혼합되어 화면상에 나타나는 비트(beat)를 제거할 수 있다. Accordingly, the local oscillation frequency and the interference wave input can be mixed to remove the beat appearing on the screen.

Claims (2)

국부 발진주파수를 제공하는 MOPLL IC와, 상기 MOPLL IC에 연결되어 소스 주파수를 제공하는 크리스탈, 및 상기 크리스털과 접지 사이에 연결된 로드 캐패시터를 포함하는 튜너에서,In a tuner comprising a MOPLL IC providing a local oscillation frequency, a crystal coupled to the MOPLL IC to provide a source frequency, and a load capacitor coupled between the crystal and ground, 상기 크리스탈의 주파수 편차를 조정하기 위하여 주파수 보상용 가변용량 캐패시터를 상기 로드 캐패시터와 병렬로 연결하는 것을 특징으로 하는 크리스탈 주파수 편차 조정회로.And a variable capacitance capacitor for frequency compensation in parallel with the load capacitor in order to adjust the frequency deviation of the crystal. 청구항 1에 있어서,The method according to claim 1, 상기 크리스탈의 주파수 편차는 ± 10㎐로 설정되고, 상기 주파수 보상용 가변용량 캐패시터는 0 내지 40㎊ 범위 내에서 변화되는 것을 특징으로 하는 크리스탈 주파수 편차 조정회로.And the frequency deviation of the crystal is set to ± 10 Hz, and the variable capacitance capacitor for frequency compensation is varied within a range of 0 to 40 Hz.
KR1020050082836A 2005-09-06 2005-09-06 Circuit for adjusting crystal frequency deviation KR20070027346A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20150031436A (en) * 2012-06-21 2015-03-24 케이엘에이-텐코 코포레이션 Laser crystal degradation compensation

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20150031436A (en) * 2012-06-21 2015-03-24 케이엘에이-텐코 코포레이션 Laser crystal degradation compensation

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