ADF7021

Preliminary Technical Data

Rev. PrI | Page 34 of 44

REGISTER 6—IF FINE CAL SETUP REGISTER

IF CAL LOWER TONE DIVIDER

IF CAL UPPER TONE DIVIDER

IF CAL DWELL TIME

ADDRESS

BITS

FC1

0

1

IF FINE CAL

DISABLED

ENABLED

UT3

0

0

0

.

.

1

UT1

1

0

1

.

.

1

IF CAL UPPER

TONE DIVIDE

1

2

3

.

.

UT2

0

1

1

.

.

1

UT8

0

0

0

.

.

1

...

...

...

...

...

...

...

255

LT3

0

0

0

.

.

1

LT1

1

0

1

.

.

1

1

2

3

.

.

LT2

0

1

1

.

.

1

LT8

0

0

0

.

.

1

...

...

...

...

...

...

...

255

IF CAL LOWER

TONE DIVIDE

CD3

0

0

0

.

.

1

CD1

1

0

1

.

.

1

IF CAL

DWELL TIME

1

2

3

.

.

CD2

0

1

1

.

.

1

CD7

0

0

0

.

.

1

...

...

...

...

...

...

...

127

Figure 38.

Register 6—IF Fine Cal Setup Register Comments

•

A fine IF filter calibration is set by enabling the IF_FINE_CAL Bit (DB4). A fine calibration is then carried out only when Register 5

is written to and Bit R5_DB4 is set.

•

The IF upper and lower tones used during fine filter calibration should be set as follows:

kHz

160

_

_

_

_

=

DIVIDE

TONE

LOWER

CAL

IF

XTAL

kHz

220

_

_

_

_

=

DIVIDE

TONE

UPPER

CAL

IF

XTAL

•

The IF tone calibration time is the amount of time that is spent at an IF calibration tone. It is dependent upon the sequencer clock. It

is recommended to have the IF_CAL_DWELL_TIME be at least 300 μs.

CLK

SEQ

DWELL

CAL

IF

Time

n

Calibratio

Tone

IF

_

_

_

=

The total time for a fine IF filter calibration is = IF Tone Calibration Time × 10.