AD831

REV. B

–12–

Connections Quadrature Demodulation

Two AD831 mixers may have their RF inputs connected in par-

allel and have their LO inputs driven in phase quadrature (Fig-

ure 27) to provide demodulated in-phase (I) and quadrature

(Q) outputs. The mixers’ inputs may be connected in parallel

and a single termination resistor used if the mixers are located in

close proximity on the PC board.

DEMODULATED

QUADRATURE

OUTPUT

NC

–5V

0.1µF

0.1µF

+5V

51.1

Ω

0.1µF

+5V

–5V

0.1µF

–5V

0.1µF

IF

INPUT

0.1µF

+5V

IFN

VP

IFP

AP

GND

VN

RFP

RFN

VN

VP

LON

LOP

VP

GND

BIAS

VN

AD831

Top View

50

Ω

50

Ω

6

7

8

4

5

9

10

11

12

13

AN

VFB

COM

OUT

14

15

16

17

18

1

2

3

19

20

LO INPUT

AT 90

°

–10 dBm

DEMODULATED

IN-PHASE

OUTPUT

NC

–5V

0.1µF

0.1µF

+5V

51.1

Ω

0.1µF

+5V

–5V

0.1µF

–5V

0.1µF

0.1µF

+5V

LO INPUT

AT 0

°

–10 dBm

51.1

Ω

IFN

VP

IFP

AP

GND

VN

RFP

RFN

VN

VP

LON

LOP

VP

GND

BIAS

VN

AD831

Top View

50

Ω

50

Ω

6

7

8

4

5

9

10

11

12

13

AN

VFB

COM

OUT

14

15

16

17

18

1

2

3

19

20

Figure 27. Connections for Quadrature Demodulation