TL441

LOGARITHMIC AMPLIFIER

SLVS328 – OCTOBER 2000

12

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

10 – 4

10 –3

10 –2

10 –1

101

1

Input Voltage – V

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

TRANSFER CHARACTERISTICS

1 k

Ω

910

Ω

VCC + = 4 V

VCC – = – 4 V

5 k

Ω

1 k

Ω

910

Ω

100

Ω

15 k

Ω

2 k

Ω

2 k

Ω

20 k

Ω

2 k

Ω

Slope

5 k

Ω

Input

Output

Z

Z

A1

A2

Y

Y

B1

B2

TL441

5 k

Ω

Origin

100

Ω

+

–

+

–

+

–

VCC + = 4 V

VCC – = – 4 V

NOTES: A. Inputs are limited by reducing the supply voltages for the input amplifiers to

±4 V.

B. The gains of the input amplifiers are adjusted to achieve smooth transitions.

Figure 15. Logarithmic Amplifier With Input Voltage Range Greater Than 80 dB