520 - 25 - 4

4

For normal video mixer operation, the control range (SPAN) is

usually 0 to 1V and will occur when A

V

an effect such that the output signal contains 100% of Channel

B when V

the above conditions, the general unity gain transfer function

reduces to:

V

Since the operation of the mixer is limited to two quadrants, no

signal inversions occur if the control voltage exceeds the

range zero to one volt in either direction. The topology is

designed so that once the control voltage reaches either end

of its range, the channel which is ON remains fully ON and the

OFF channel remains fully OFF.

0.1

or LINK

GT4122

CONTROL

OFFSET

RV2

100

C3

0.1

COUT

-5V

C6 0.1

ROUT

10k or

OPEN

+5V

B VIDEO INPUT

CONTROL INPUT

Z1

6.2V

R3

1k

RV1

200

R2

1k

C2 0.1

R1

560

(0.5V)

R4

5.6k

50%

GAIN

B BLACK

LEVEL

ADJUST

A BLACK

LEVEL

ADJUST

75

if required

RV4

500

RV5

500

1

2

4

3

17

18

19

20

+10V

-10V

GND

COMP

OUT

6

5

7

15

16

14

+IN B

S1

-IN B

-IN A

9

8

10

12

13

S2

+IN A

11

C5

47

-10V

C5

47

C1

0.1

5 - 25pF

CCOMP

RV6

1k

VREF

ADJUST

RV3

SPAN

ADJUST

C5

0.1

C7 0.1

A VIDEO INPUT

75

if required

75

if required

IC2

CLC110

1

4

5

8

+

+

VIDEO OUT

1K

All resistors in ohms, all capacitors in

µF unless otherwise stated.

Fig. 1 Test Circuit