LA7770 データシートの表示（PDF） - SANYO -> Panasonic

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LA7770

FSK Receiver for CATV Use

SANYO -> Panasonic 

LA7770

In the Fig. 6 phase shifter,

1

V2 =

jωC2+

1

R

+jwL

=

1

V1

1

jωC1

+

jωC2+

1

1

R

+jwL

ω2L (C1+C2)–1 –j 1

ω2LC1

jωCR

Requirements to achieve a 90° phase shift will be :

ω2L (C1+C2)=1

∴ƒ=

1

2π√L (C1+C2)

ω=

1

√L (C1+C2)

V2 =

1

V1

√

ω2L (C1+C2)–1

2

+

1

2

ω2LC1

jωC1R

At the tuning point :

V2 =

√ V1

1

1

2

ωC1R

=ωC1R

(5) Meter Drive and Squelch

A forward bias is provided to the meter drive dedicated detector, to enable its detector diode to detect low-level

signals. In addition, a bias canceler is also provided to eliminate the offsetting current in a no-signal mode created

by the forward bias. Furthermore, to broaden the linear operating range, signals are fetched from the 3rd and 5th

stage outputs of the limiter amplifier, for composition together after level detection.

Fig. 7

No.2208–5/7

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