Analog Devices ADF7021-V Manual page 20

ADF7021-V
–100
–102
–104
–106
–108
DISCRIMINATOR BANDWIDTH =
–110
2× FSK FREQUENCY DEVIATION
–112
–114
–116
DISCRIMINATOR BANDWIDTH =
1× FSK FREQUENCY DEVIATION
–118
0 0.2 0.4
MODULATION INDEX
Figure 29. 2FSK Sensitivity vs. Modulation Index and Correlator
Discriminator Bandwidth
0
–1
–2
VITERBI DETECTION
–3
–4
–5
3FSK MODULATION
V = 3.0V, TEMP = 25°C
DD
DATA RATE = 9.6kbps
–6
f
= 2.4kHz
DEV
RF FREQ = 868MHz
IFBW = 18.75kHz
–7
–120 –118 –116 –114 –112 –110 –108 –106 –104 –102 –100
INPUT POWER (dBm)
Figure 30. 3FSK Receiver Sensitivity Using Viterbi Detection and
Threshold Detection
RF FREQ = 860MHz
2FSK MODULATION
DATA RATE = 9.6kbps
IFBW = 25kHz
V = 3.0V
DD
TEMPERATURE = 25°C
0.6 0.8 1.0 1.2
THRESHOLD DETECTION
–70
–80
IP3 = –5dBm
–90
–100
IP3 = –3dBm
–110
–120
–130
(LOW GAIN MODE)
Figure 31. 2FSK Receiver Sensitivity vs. LNA Gain/IF Filter Gain and Mixer
Linearity Settings (Input IP3 at Each Setting Also Shown)
Rev. 0 | Page 20 of 60
2FSK MODULATION
DATA RATE = 9.6kbps
f
= 4kHz
DEV
HIGH MIXER
IFBW = 12.5kHz
LINEARITY
DEMOD = CORRELATOR
SENSITIVITY @ BER = 10
IP3 = –9dBm
DEFAULT
IP3 = –13.5dBm
MIXER
LINEARITY
3, 72 10, 72
(MEDIUM GAIN MODE)
LNA GAIN, FILTER GAIN
–3
IP3 = –20dBm
IP3 = –24dBm
30, 72
(HIGH GAIN MODE)