September 1999

ML6421

*

Triple Phase and Sinx/x Equalized,

Low-Pass Video Filter

1

GENERAL DESCRIPTION

The ML6421 monolithic BiCMOS 6th-order filter provides

fixed frequency low pass filtering for video applications.

This triple phase-equalized filter with Sinx/x correction is

designed for reconstruction filtering at the output of a

Video DAC.

Cut-off frequencies are either 5.5, 8.0, or 3.0MHz. Each

channel incorporates a 6th-order lowpass filter, a first

order all-pass filter, a gain boost circuit, and a 75

Ω coax

cable driver. A control pin (Range) is provided to allow

the inputs to swing from 0 to 1V, or 0.5 to 1.5V, by

providing a 0.5V offset to the input.

The unity gain filters are powered from a single 5V supply,

over 150

Ω (0.5V to 2.5V) with the internal coax drivers.

BLOCK DIAGRAM

*Some Packages Are Obsolete

FEATURES

s

5.5, 8.0, 9.3, or 3.0MHz bandwidth

s

1x or 2x gain

s

6th-order filter with phase and amplitude equalizer

s

>40dB stopband rejection

s

No external components or clocks

s

±10% frequency accuracy over maximum supply

and temperature variation

s

<2% differential gain <2° differential phase

s

<25ns group delay variation

s

s

5V ±10% operation

15

5

6

4

BUF

1X/2X

BUF

LOW PASS

FILTER A

3k

Ω

1k

Ω

3.33k

Ω

16

1

BUF

LOW PASS

FILTER B

9

3

3.33k

Ω

2

14

BUF

LOW PASS

FILTER C

7

3.33k

Ω

8

11

GNDC

13

GNDA

12

GND

GND

RANGE

GNDB

3k

Ω

1k

Ω

3k

Ω

1k

Ω

SINX/X

EQUALIZER

SINX/X

EQUALIZER

SINX/X

EQUALIZER

ALL

PASS

FILTER

ALL

PASS

FILTER

ALL

PASS

FILTER

1X/2X

BUF

1X/2X

BUF

Triple Input/Anti-aliasing Video Filter

1x GAIN

2x GAIN

ML6221-1

ML6421-3

ML6421-4

ML6421-5

ML6421-7

FilterA

5.5MHz

8.0MHz

8.0MHz

5.5MHz

9.3MHz

Filter B

5.5MHz

8.0MHz

3.0MHz

5.5MHz

9.3MHz

Filter C

5.5MHz

8.0MHz

3.0MHz

5.5MHz

9.3MHz