EVAL-ADF7021DBZ5 Datasheet, PDF (49/64 Pages) Analog Devices – High Performance Narrow-Band Transceiver IC

Data Sheet
REGISTER 2—TRANSMIT MODULATION REGISTER
TxDATA_
INVERT
Tx_FREQUENCY_DEVIATION
POWER_AMPLIFIER PA_BIAS PA_RAMP
ADF7021
MODULATION_
SCHEME
ADDRESS
BITS
PA2 PA1 PA BIAS
0 0 5µA
0 1 7µA
1 0 9µA
1 1 11µA
PE1 POWER AMPLIFIER
0 OFF
1 ON
DI2 DI1 TxDATA INVERT
0 0 NORMAL
0 1 INVERT CLK
1 0 INVERT DATA
1 1 INV CLK AND DATA
TFD9 ...
0 ...
0 ...
0 ...
0 ...
.
...
1 ...
TFD3 TFD2 TFD1 fDEV
0000
0011
0102
0113
.
.
.
.
1 1 1 511
NRC1 RAISED COSINE ALPHA
0 0.5 (Default)
1 0.7
P6 .
.
0.
.
0.
.
0.
.
0.
.
.
.
.
.
.
.
11.
PR3 PR2 PR1 PA RAMP RATE
0 0 0 NO RAMP
0 0 1 256 CODES/BIT
0 1 0 128 CODES/BIT
0 1 1 64 CODES/BIT
1 0 0 32 CODES/BIT
1 0 1 16 CODES/BIT
1 1 0 8 CODES/BIT
1 1 1 4 CODES/BIT
P2 P1 PA LEVEL
0 0 0 (PA OFF)
0 1 1 (–16.0 dBm)
102
113
.
.
.
.
.
.
11
63 (13 dBm)
S3 S2 S1 MODULATION SCHEME
0 0 0 2FSK
0 0 1 GAUSSIAN 2FSK
0 1 0 3FSK
0 1 1 4FSK
1 0 0 OVERSAMPLED 2FSK
1 0 1 RAISED COSINE 2FSK
1 1 0 RAISED COSINE 3FSK
1 1 1 RAISED COSINE 4FSK
Figure 64. Register 2—Transmit Modulation Register Map
The 2FSK/3FSK/4FSK frequency deviation is expressed by the
following:
Direct output
Frequency Deviation [Hz] =
Tx_FREQUENCY_DEVIATION × PFD
2¹⁶
With RF_DIVIDE_BY_2 (R1_DB18) enabled
Frequency Deviation [Hz] =
0.5
×
Tx_FREQUENCY_DEVIATION
2¹⁶
×
PFD
where Tx_FREQUENCY_DEVIATION is set by DB[19:27] and
PFD is the PFD frequency.
In the case of 4FSK, there are tones at ±3 × the frequency
deviation and at ±1 × the deviation. The power amplifier (PA)
ramps at the programmed rate (R2_DB[8:10]) until it reaches
its programmed level DB[13:18]. If the PA is enabled/disabled
by the PA_ENABLE bit (DB7), it ramps up and down. If it is
enabled/disabled by the Tx/Rx bit (R0_DB27), it ramps up and
turns hard off.
R-COSINE_ALPHA sets the roll-off factor (alpha) of the raised
cosine data filter to either 0.5 or 0.7. The alpha is set to 0.5 by
default, but the raised cosine filter bandwidth can be increased
to provide less aggressive data filtering by using an alpha of 0.7.
Rev. B | Page 49 of 64