LTC5555

24

Rev. 0

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TYPICAL APPLICATIONS

5.6GHz to 7.2GHz RF Application with Wideband IF

The LTC5555’s RF inputs are optimized for operation

up to 6GHz, but may be used up to 8GHz with degraded

performance. Figure 18 shows an example where the RF

input is matched from 5.6GHz to 7.2GHz and the IF output

Figure 18. 5.6GHz to 7.2GHz Input Matching with Wideband IF Output Match

Figure 19. Measured Performance for 5.6GHz to 7.2GHz Downconverter with Wideband IF Output

5555 F17

LTC5555

LO

RF

RF

(50 )

1.1pF

0.2pF

680nH

680nH

IF

12nH

12nH

10nF

IF

(100 DIFF)

10nF

18nH

1nF

18nH

680nH

680nH

1nF

3dB

6dB

9dB

12dB

15dB

0dB

0dB

15dB

IIP3

IF = 470MHz

LOW SIDE LO

RF FREQUENCY (GHz)

5.5 5.7 5.9 6.1 6.3 6.5 6.7 6.9 7.1 7.3

–9

–6

–3

0

3

6

9

12

15

18

21

24

5555 F18a

Conv Gain and IIP3 vs RF Frequency

and IF Attenuation (3dB Steps)

6.5GHz Conv Gain, IIP3, and SSB NF

vs IF Attenuation (0.5dB Steps)

Conv Gain vs IF Frequency and

Attenuation, Swept RF/Fixed LO

is matched for wideband operation up to 800MHz. The

measuredperformanceissummarizedinFigure19,where

the RF input is swept from 6.1GHz to 6.9GHz, with a fixed

6.03GHz LO, resulting in a wideband 70MHz to 870MHz

IF output, centered at 470MHz.

IIP3

NF

IF = 470MHz

LOW SIDE LO

FULL PWR

RED PWR

IF ATTENUATION (dB)

0

2

4

6

8

10

12

14

16

–9

–6

–3

0

3

6

9

12

15

18

21

3

6

9

12

15

18

21

24

27

30

33

5555 F18b

0dB

RF = 6.1GHz to 6.9GHz

LO = 6.03GHz

3dB

6dB

9dB

12dB

15dB

IF FREQUENCY (MHz)

70 170 270 370 470 570 670 770 870

–10

–8

–6

–4

–2

0

2

4

6

8

10

5555 F18c