7

having resistance RL is about 1/30 of that of the test circuit without the resistance. This is because the carrier (photocurrent)

ratio (CTR). Compare the voltage level of the output waveform in Photo 4 with that of the output waveform in Photo 2. The

current transfer ratio of the test circuit having a base-emitter resistor of 200 k

Ω is half or less of that of the test circuit without the

resistance. (See 3.3 for reduction of the current transfer ratio CTR.)

tics.

x

Sample Solid line:

Current transfer ratio of 166%

Dotted line:

Current transfer ratio of 274%

at Ir = 5mA

tr

td

1000

500

200

100

50

20

10

5

2

1

100

500

1 k

5 k

10 k

50 k 100 k

tf

ts

Vcc=5V

Vo

51

Ω

I

Ω)

Ω

Solid line:

Emitter follower

Dotted line: Emitter grounded

160

140

120

100

80

60

40

20

0

100

200

500

1000

Ω)

Ω)

1000

500

200

100

50

20

10

5

2

1

100

500

1 k

5 k

10 k

50 k 100 k

Vo

51

Ω

x

Sample Solid line:

Current transfer ratio of 166%

Dotted line:

Current transfer ratio of 274%

at Ir = 5 mA

Ω)

Ω

Solid line:

Emitter follower

Dotted line: Emitter grounded

160

140

120

100

80

60

40

20

0

100

200

500

1000