ADL5391

Rev. 0 | Page 12 of 16

0

–65

–60

–55

–50

–45

–40

–35

–30

–25

–20

–15

–10

–5

10

100

200

300

400

500

600

700

800

900 1000

FREQUENCY (MHz)

BLEEDTHRU GAIN

SECOND HARMONIC GAIN

THIRD HARMONIC GAIN

Figure 18. Single-Ended (DC) ADL5391 Used as a Harmonic Generator

21Ω

74Ω

21Ω

74Ω

XIN

YIN

150Ω

62Ω

5dB PAD

5dB PAD

10dB PAD

53Ω

53Ω

200Ω

XM

XP

YM

YP

WP

WM

Figure 19. Setup for Single-Ended Data

Use as a Detector

The ADL5391 can be used as a square law detector. When

amplitude squaring is performed, there are components of the

multiplier output that correlate to the signal bleedthrough and

second harmonic, as seen in Equation 4. However, as noted in

the Squaring and Frequency Doubling section, there is also a dc

component that is directly related to the offset and the squared

input magnitude. If a signal is split and feed into the X and Y

inputs and a low-pass filter were place on the output, the resulting

dc signal would be directly related to the square of the input

magnitude. The intercept of the response will shift slightly from

part to part (and over temperature) with the offset, but this can

be removed through calibration. Figure 20 shows the response

of the ADL5391 as a square law detector, Figure 21 shows the

error vs. the input power, and Figure 22 shows the

configuration used.

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

00

0.7

0.6

0.5

0.4

0.3

0.2

0.1

.8

Figure 20. ADL5391 Used as Square Law Detector DC Output vs. Square of Input

1.6

–0.2

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

–30

10

5

0

–5

–10

–15

–20

–25

PIN X (dBm)

Figure 21. ADL5391Used as a Square Law Detector Error vs. Power Input

T1

45nF

40µH

40µH

74µH

74µH

J2

WM

J1

WP

XM

XP

YM

YP

11

12

13

14

WP

WM

6

5

R2

56.2Ω

TC1-1-13M

T3

C7

0.1µF

C18

0.1µF

J6

YP

R1

56.2Ω

TC1-1-13M

T2

C4

0.1µF

C20

0.1µF

J8

XP

R4

100Ω

R12

OPEN

40nF

R6

24.9Ω

R5

24.9Ω

Figure 22. Schematic for ADL5391 Used as Square Law Detector