TL441AM

LOGARITHMIC AMPLIFIER

SLFS038 – JUNE 1976 – REVISED FEBRUARY 1989

13

POST OFFICE BOX 655303

APPLICATION INFORMATION

2 k

Ω

2 k

Ω

Origin

20 k

Ω

2 k

Ω

2 k

Ω

Slope

A1

A2

Y

Y

1/2

TL441

Input

A

Output

W

+

–

–

+

NOTE: Adjust the slope to correspond to the base “a”.

Exponential to any base: W = a.

Figure 18. Raising a Fixed Number to a Variable Power

+

–

20 k

Ω

20 k

Ω

Input

1

2.2 k

Ω

0.2

µF

Output

1

Input

2

Output

2

TL592

TL592

0.2

µF

1 k

Ω

1 k

Ω

Gain Adj.

2.2 k

Ω

2.2 k

Ω

2.2 k

Ω

0.2

µF

0.2

µF

1 k

Ω

1 k

Ω

0.2

µF

Gain Adj. = 400

Ω

For 30 dB

Gain Adj. = 400

Ω

For 30 dB

0.2

µF

TL592

TL592

50

Ω

50

Ω

50

Ω

Open

Open

CA2 CA2’

Y

Y

Z

Z

CB2 CB2’

A1

A2

B1

B2

TL441

10

k

Ω

10

k

Ω

VCC –

Gain Adj.

+

–

+

–

+

–

50

Ω

+

–

+

–

Figure 19. Dual-Channel RF Logarithmic Amplifier With 50-dB Input Range Per Channel at 10 MHz