8

LT1203/LT1205

S

APPLICATI

I FOR ATIO

CMOS MUX Channel-to-Channel Switching Transient

OUTPUT

1V/DIV

LT1203/05 • AI02

NOTE: 50 TIMES LARGER THAN LT1203 TRANSIENT

LT1203/05 • AI03

OUTPUT

(PIN 7)

CHANNEL 1 = 0V

CHANNEL 2 = 2MHz SINEWAVE

LOGIC

(PIN 5)

LT1203 Switching Inputs

CMOS MUX shows glitches to be 50 times larger than on

the LT1203. Also shown is the output of the LT1203

switching on and off a 2MHz sinewave cleanly and without

abnormalities.

Pixel Switching

The multiplexers are fabricated on LTC's Complementary

Bipolar Process to attain fast switching speed, high band-

width, and a wide supply voltage range compatible with

traditional video systems. Channel-to-channel switching

time and Enable time are both 25ns, therefore delay is the

same when switching between channels or between ICs.

To demonstrate the switching speed of the LT1203/LT1205

the RGB MUX of Figure 1 is used to switch RGB Worksta-

tion inputs with a 22ns pixel width. Figure 2a is a photo

showing the Workstation output and RGB MUX output.

The slight rise time degradation at the RGB MUX output is

due to the bandwidth of the LT1260 current feedback

amplifier used to drive the 75

Ω cable. In Figure 2b, the

LT1203 switches to an input at zero at the end of the first

pixel and removes the following pixels.

+1

1

2

3

4

5

6

7

8

16

15

14

13

1

2

3

4

8

7

6

5

12

1

16

15

14

13

12

11

10

9

2

3

4

5

6

7

8

LT1260

11

10

9

+1

+1

+1

LT1205

LT1203/05 • F01

+1

+1

LT1203

R4

75

Ω

J4

GREEN 2

J7

LOGIC

R6

75

Ω

C1

0.1

µF

C2

0.1

µF

C3

4.7

µF

C4

4.7

µF

J6

BLUE 2

R8*

10k

R13

1.5k

R15

1.5k

R9*

10k

*OPTIONAL

R14

1.5k

R7*

10k

R5

75

Ω

J5

BLUE 1

R3

75

Ω

J3

GREEN 1

R2

75

Ω

J2

RED 2

R1

75

Ω

J1

RED 1

–

+

R12

1.5k

R10

1.5k

R11

1.5k

R

G

B

+

GND

J8

ENABLE

J9

RED

J10

GREEN

J11

BLUE

R16

75

Ω

R17

75

Ω

R18

75

Ω

Figure 1. RGB MUX

INPUT

1V/DIV

LOGIC

CONTROL