ADF7021 datasheet(20/64 Pages) AD

20 / 64 page

ADF7021

Data Sheet

Rev. B | Page 20 of 64

FREQUENCY OFFSET (MHz)

–10

–22

–18

–14

–10

–6

–2 0 2

RF FREQ = 868MHz

WANTED SIGNAL

(10dB ABOVE SENSITIVITY

POINT) = 2FSK,

fDEV = 4kHz,

DATA RATE = 9.8kbps

BLOCKER = 2FSK,

fDEV = 4kHz,

DATA RATE = 9.8kbps

VDD = 3.0V

TEMPERATURE = 25°C

Figure 23. Wideband Interference Rejection

–140

–120

–100

–80

–60

–40

–20

–122.5 –112.5 –102.5 –92.5

–82.5

–72.5

–62.5

–52.5

–42.5

ACTUAL RF INPUT LEVEL

RF INPUT (dBm)

RSSI

READBACK LEVEL

Figure 24. Digital RSSI Readback Linearity

–10

429.80 429.85 429.90 429.95 430.00 430.05 430.10 430.15 430.20

RF FREQ = 430MHz

EXTERNAL VCO INDUCTOR

DATA RATE = 9.6kbps

TEMPERATURE = 25°C, VDD = 3.0V

RF FREQUENCY (MHz)

CALIBRATED

UNCALIBRATED

Figure 25. Image Rejection, Uncalibrated vs. Calibrated

MODULATION INDEX

–118

–116

–114

–112

–110

–108

–106

–104

–102

–100

0.2

0.4

0.6

0.8

1.0

1.2

RF FREQ = 860MHz

2FSK MODULATION

DATA RATE = 9.6kbps

IF BW = 25kHz

VDD = 3.0V

TEMPERATURE = 25°C

DISCRIMINATOR BANDWIDTH =

1× FSK FREQUENCY DEVIATION

DISCRIMINATOR BANDWIDTH =

2× FSK FREQUENCY DEVIATION

Figure 26. 2FSK Sensitivity vs. Modulation Index vs. Correlator

Discriminator Bandwidth

–120 –118 –116 –114 –112 –110 –108 –106 –104 –102 –100

3FSK MODULATION

VDD = 3.0V, TEMP = 25°C

DATA RATE = 9.6kbps

fDEV = 2.4kHz

RF FREQ = 868MHz

IF BW = 18.75kHz

INPUT POWER (dBm)

–7

–6

–5

–4

–3

–2

–1

VITERBI DETECTION

THRESHOLD DETECTION

TYPICALLY

3dB

Figure 27. 3FSK Receiver Sensitivity Using Viterbi Detection and

Threshold Detection

–1

–3

RF I/P LEVEL = –70dBm

DATA RATE = 9.7kbps

fDEV (inner) = 1.2kHz

22452 ACQS

M 50µs

IF BW = 25kHz

POST DEMOD BW = 12.4kHz

Figure 28. 4FSK Receiver Eye Diagram Measure Using the Test DAC Output

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