la7567b Sanyo Semiconductor Corporation, la7567b Datasheet - Page 10

• Manufacturer Part Number: la7567b
• Description: Tv And Vcr Vif/sif If Signal-processing Circuit With Pal/ntsc Multi-format Audio Support
• Manufacturer: Sanyo Semiconductor Corporation

Continued from preceding page.
Pin No.
6
7
8
9
APC FILTER
EQ amp
Pin
• Equalizer circuit. This circuit is used to correct the video
• Notes on equalizer amplifier design
• Approach used in the equalizer amplifier
Where G is the voltage-follower amplifier gain.
Assume:
Then:
• R1 is the IC internal resistance, and is 1 kΩ. In the
• PLL detector APC filter connection. The APC time constant
signal frequency characteristics.
Pin 8 is the EQ amplifier input. This amplifier amplifies a
1.5-V p-p video signal to 2-V p-p.
The equalizer amplifier is designed as a voltage follower
amplifier with a gain of about 2.3 dB. When used for
frequency characteristics correction, a capacitor, inductor,
and resistor must be connected in series between pin 7
and ground.
If vi is the input signal and vo is the output signal, then:
vin: Imaginary short
G: About 2.3 dB
vin
application design, simply select Z to correspond to the
desired characteristics. However, since the EQ amplifier
gain will be maximum at the resonant point defined by Z,
care is required to assure that distortion does not occur.
is switched internally in the IC. When locked, the VCO is
controlled by loop A and the loop gain is reduced. When
unlocked and during weak field reception, the VCO is
controlled by loop B and the loop gain is increased.
For this APC filter we recommend:
R = 150 to 390 Ω
C = 0.47 µF
AV = —— = —— +1
—— +1 (vi + vin) = Vo
R1
2
0.
voG
vi
R1
Z
Description
LA7567B, 7567BM
G
8
EQ INPUT
200
2 k
7
C
L =Z
R
1 k
Equivalent circuit
1 k
1 k
9
A
FROM
APC DET
1 k
Continued on next page.
B
R
AGC
EQ OUTPUT
+
C
No. 6099-10/15
6
A12032
A12033
A12034