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| 型號(hào)： | LA7578 |
| 文件頁(yè)數(shù)： | 8/18頁(yè) |
| 文件大?。?/td> | 252K |
| 代理商： | LA7578 |
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If this phase distortion (
θ
) appears, the PLL VCO will be modulated in synchronization with the error voltage, which causes the
generation of a buzz. At Sanyo, this buzz generated by the phase distortion (
θ
) is called ‘‘Nyquist buzz.’’ The LA7578N includes a
new Nyquist buzz canceller circuit that suppresses this Nyquist buzz generated by the phase distortion (
θ
) in an effort to greatly
improve the buzz characteristics. Fig. 3 shows the PLL detection system in the LA7578N, which uses this Nyquist buzz canceller
circuit.
Fig. 3 PLL Detector with Nyquist Buzz Canceller
In the PLL detection system with the Nyquist buzz canceller, even if phase distortion such as that shown in A is generated, the
phase distortion in the APC detection output can be eliminated by generating and adding in a quasi-reverse phase buzz signal.
Nyquist buzz
Quasi-reverse phase buzz
Fig. 4 Nyquist Buzz Canceller Waveforms
The effect of this Nyquist buzz canceller circuit is to broadly suppress the buzz (f
H
harmonic ) generated as a sideband of the SIF
beat signal (4.5 MHz). As a result, great improvements can be made in regard to the buzz beat generated during demodulation of
Japan audio multiplexing (L-R) and the buzz characteristics during demodulation of U.S. MTS (Multichannel TV Sound) (L-R).
Furthermore, because this Nyquist buzz cancellation method has no effect on the time constant of the PLL loop, it is also possible
to try to improve various characteristics, by making it possible to, for example, design an APC filter that is not readily affected by
flyback pulses (F.B.P), etc.
LA7578N
No.4037-8/18
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LA7640 | |
| LA7685 | |
| LA7802 | Analog IC |
| LA7900 | |
| LA7905 | |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LA7578N | 制造商:SANYO 制造商全稱(chēng):Sanyo Semicon Device 功能描述:IF Signal Processing (Super PLL-II VIF + SIF) Circuit for TVs and VCRs |
| LA7583 | 制造商:SANYO 制造商全稱(chēng):Sanyo Semicon Device 功能描述:IF Signal Processing Circuit (A2C PLL VIF + SIF) for TVs and VCRs |
| LA7590 | 制造商:未知廠(chǎng)家 制造商全稱(chēng):未知廠(chǎng)家 功能描述:Analog IC |
| LA7600 | 制造商:未知廠(chǎng)家 制造商全稱(chēng):未知廠(chǎng)家 功能描述: |
| LA7601 | 制造商:未知廠(chǎng)家 制造商全稱(chēng):未知廠(chǎng)家 功能描述:Consumer IC |
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