EVAL-ADF7021DBZ5 Datasheet, PDF (53/64 Pages) Analog Devices – High Performance Narrow-Band Transceiver IC

Data Sheet
REGISTER 6—IF FINE CAL SETUP REGISTER
IF_CAL_DWELL_TIME
IF_CAL_UPPER_TONE_DIVIDE
IF_CAL_LOWER_TONE_DIVIDE
ADF7021
ADDRESS
BITS
IRD1 IR CAL SOURCE ÷2
0 SOURCE ÷2 OFF
1 SOURCE ÷2 ON
IR CAL SOURCE
IRC2 IRC1 DRIVE LEVEL
0 0 OFF
0 1 LOW
1 0 MED
1 1 HIGH
CD7 ...
0
...
0
...
0
...
.
...
.
...
1
...
UT8 UT7 ...
0 0 ...
0 0 ...
0 0 ...
. . ...
. . ...
0 1 ...
UT3 UT2 UT1
001
010
011
.
.
.
.
.
.
111
IF CAL UPPER
TONE DIVIDE
1
2
3
.
.
127
FC1 IF FINE CAL
0 DISABLED
1 ENABLED
IF CAL
CD3 CD2 CD1 DWELL TIME
0011
0102
0113
.
.
.
.
.
.
.
.
1 1 1 127
IF CAL LOWER
LT8 LT7 ... LT3 LT2 LT1 TONE DIVIDE
0 0 ... 0 0 1 1
0 0 ... 0 1 0 2
0 0 ... 0 1 1 3
. . ... .
.
.
.
. . ... .
.
.
.
1 1 ... 1 1 1 255
Figure 68. Register 6—IF Fine Cal Setup Register Map
A fine IF filter calibration is set by enabling the IF_FINE_CAL
Bit (R6_DB4). A fine calibration is then carried out only when
Register 5 is written to and R5_DB4 is set.
Set the IF upper and lower tones used during fine filter
calibration as follows:
IF
_
CAL
_
XTAL
LOWER _ TONE
_
DIVIDE
×
2
=
65.8
kHz
XTAL
= 131.5 kHz
IF _ CAL _ UPPER _ TONE _ DIVIDE × 2
The IF tone calibration time is the amount of time that is spent
at an IF calibration tone. It is dependent on the sequencer clock.
For best practice, is recommended to have the IF tone
calibration time be at least 500 µs.
IF Tone Calibration Time = ^{IF _ CAL _ DWELL _ TIME}
SEQ CLK
The total time for a fine IF filter calibration is
IF Tone Calibration Time × 10.
DB[28:30] control the internal source for the image rejection
(IR) calibration. The IR_CAL_SOURCE_DRIVE_LEVEL bits
(DB[28:29]) set the drive strength of the source, whereas the
IR_CAL_SOURCE_÷2 bit (DB30) allows the frequency of the
internal signal source to be divided by 2.
Rev. B | Page 53 of 64