February 1997
PRELIMINARY
ML6424*/ML6425*
CCIR601 Video Lowpass Filter
with Optional Sinx/x Correction
GENERAL DESCRIPTION
The ML6424 is a monolithic BiCMOS Video Lowpass
Filter IC, incorporating a 5th order Elliptic (Cauer) lowpass
filter, a third order allpass filter, and a 75Ω coax cable
driver. The ML6425 additionally provides sinx/x amplitude
correction. These active lowpass filters are available with
a 2.75MHz (-2) or a 5.50MHz (-1) cutoff frequency.
The input signal can be either AC or DC coupled under
the control of the MODE pin. In the DC coupled case, a
control pin (RANGE) is provided to allow the inputs to
swing down to ground. Internal self clamping is provided
for AC coupled signals.
The ML6424 and ML6425 are powered by a single 5V
supply, and can drive 1V
PP
into 75Ω (0.5V to 1.5V), or
2V
PP
into 150Ω (0.5 to 2.5V). The maximum output swing
from 0.5V to 2.5V allows easy interface to the ML6400
family of A/D converters.
FEATURES
s
s
s
s
s
s
s
s
s
s
s
s
External or internal input clamping with pulse output
for synchronous clamping of multiple filters
Frequency tunable with R
EXT
:
±10%
±0.25dB
ripple
>40dB attenuation at f > 1.45 x f
C
(w/o sinx/x)
>35dB attenuation at f > 1.45 x f
C
(with sinx/x)
–12dB attenuation at f = 1.23 x f
C
Group delay distortion:
±20ns
up to 0.9 x f
C
<1% peak overshoot and ringing on 2T test pulse
0.5% diff. gain and 0.5⋅ diff. phase typical
THD <1% at 3.58 or 4.43MHz
Programmable input-output gain of 1x or 2x
5V
±5%
operation
*Some packages Are Obsolete
BLOCK DIAGRAM
+5V
GAIN
13
5
V
CC
11
V
CC
3
V
CC
1
V
CC
V
IN
P
V
IN
M
6
7
INPUT
CLAMP
+
–
BUF
5TH ORDER
LOW PASS
3RD ORDER
ALL PASS
SINX/X
+
BUF
–
15
V
OUT
P
16
V
OUT
M
MODE
12
FILTER BIAS
PULSE
4
I/O
PULSE
CONTROL
8
9
10
14
2
RANGE
R
EXT
10kΩ
1%
GND
GND
GND
Bandwidth
Sinx/x
ML6424-1
5.50MHz
No
ML6424-2
2.75MHz
No
ML6425-1
5.50MHz
Yes
ML6425-2
2.75MHz
Yes
1