LA7566 Просмотр технического описания (PDF) - SANYO -> Panasonic

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LA7566

VIF/SIF IF Signal-Processing Circuit with TV/VCR PAL and NTSC Multisound Support

SANYO -> Panasonic 

LA7566

Notes on Sanyo SAW Filters

There are two types of SAW filters, which differ in the piezoelectric substrate material, as follows:

1. Lithium tantalate (LiTaO3) SAW filter

TSF11 s s s ······ Japan

TSF12 s s s ······ US

Although lithium tantalate SAW filters have the low temperature coefficient of –18 ppm/°C, they suffer from a large

insertion loss. However, it is possible, at the cost of increasing the number of external components required, to minimize

this insertion loss by using a matching circuit consisting of coils and other components at the SAW filter output. At the

same time as minimizing insertion loss, this technique also allows the frequency characteristics, level, and other aspects

to be varied, and thus provides increased circuit design flexibility. Also, since the SAW filter reflected wave level is

minimal, the circuit can be designed with a small in-band ripple level.

2. Lithium niobate (LiNbO3) SAW filter

TSF52 s s s ······ US

TSF53 s s s ······ PAL

Although lithium niobate SAW filters have the high temperature coefficient of –72 ppm/°C, they feature an insertion loss

about 10 dB lower than that of lithium tantalate SAW filters. Accordingly, there is no need for a matching circuit at the

SAW filter output. Although the in-band ripple is somewhat larger than with lithium tantalate SAW filters, since they

have a low impedance and a small field slew, they are relatively immune to influences from peripheral circuit

components and the geometry of the printed circuit board pattern. This allows stable out-of-band trap characteristics to be

acquired. Due to the above considerations, lithium tantalate SAW filters are used in applications for the US and Japan

that have a high IF frequency, and lithium niobate SAW filters are used in PAL and US applications that have a low IF

frequency.

Notes on SAW Filter Matching

In SAW filter input circuit matching, rather than matching the IF frequency, flatter video band characteristics can be

acquired by designing the tuning point to be in the vicinity of the audio carrier rather than near the chrominance carrier.

The situation shown in figure on the right makes it easier to acquire flat band characteristics than that in figure on the left.

The high-band reduced

SAW filter characteristics

The high-band is

extended

Frequency

With the tuning set to the IF frequency

Coil Specifications

JAPAN f = 58.75 MHz

Frequency

With the tuning set to the vicinity of S and C

US f = 45.75 MHz

PAL f = 38.9 MHz

VCO coils

Test production No. 16991A

Tokyo Parts Industrial Co., Ltd.

Test production No. 16687A

Tokyo Parts Industrial Co., Ltd.

Picture

Picture

SAW filters (split)

TSF1137U

TSF1241

SOUND

SOUND

SAW filters (inter)

TSF5220

TSF5221

Tokyo Parts Industrial Co., Ltd. 236 Hinode Machi Isesaki Shi, Gunma Prefecture Japan TEL: +81-270-23-3731

Test production No. 16686A

Tokyo Parts Industrial Co., Ltd.

Picture

TSF5315

SOUND

TSF5321

TSF5344

No. 5764-10/11

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