CC1010-RTR1 datasheet(113/152 Pages) TI

113 / 152 page

CC1010

SWRS047

Page 113 of 152

17.15 VCO

Only one external inductor (L101) is

required for the VCO. The inductor will

determine the operating frequency range

of the circuit. It is important to place the

inductor as close to the pins as possible in

order to reduce stray inductance. It is

recommended to use a high Q, low

tolerance inductor for best performance.

Typical tuning range for the integrated

varactor is 20-25%.

Component values for various frequencies

are given in Table 28. Component values

for other frequencies can be found using

the SmartRF

® Studio software.

17.16 VCO and PLL self-calibration

compensate

for

supply

voltage,

temperature and process variations the

VCO and PLL must be calibrated. The

calibration is done automatically and sets

optimum VCO tuning range and optimum

charge pump current for PLL stability. The

calibration is controlled by using the CAL

After setting up the device at the operating

frequency, the TEST6 register must be

programmed (depend on operation mode).

Then the self-calibration is initiated by

setting the CAL.CAL_START bit. The

calibration result is stored internally in the

chip, and is valid as long as power is not

turned

off.

large

supply

voltage

variations

(more

than

0.5

temperature variations (more than 40

degrees) occur after calibration, a new

calibration should be performed. For more

details on the calibration data, see the

description

for

test

and

calibration

registers page 128.

When CAL.CAL_WAIT = 1 the calibration

is complete and the CAL.CAL_COMPLETE

flag is set after 25650 reference clock

cycles

(fREF,

see

the

Frequency

programming section at page 106). The

user can poll this bit, or simply wait 25650

reference

clock

cycles.

The

lowest

permitted reference frequency (1 MHz)

gives a wait time of 25.65 ms, which is the

worst case. Some calibration times for

different reference frequencies are listed in

Table 36. When CAL.CAL_WAIT = 0 it

takes 12825 cycles, but this is not

recommended.

Reference frequency

[MHz]

Calibration time

[ms]

2.4

10.69

2.0

12.83

1.5

17.10

1.0

25.65

Table 36. Calibration times

The CAL_START bit must be cleared after

the calibration is done. This will also clear

the CAL.CAL_COMPLETE status bit.

There are separate calibration values for

the two frequency registers. If the two

frequencies, A and B, differ more than 1

MHz, or different VCO currents are used

(CURRENT.VCO_CURRENT(3:0)),

the

calibration should be done separately.

When using a 10.7 MHz external IF the LO

is 10.7 MHz below/above the transmit

frequency, hence separate calibration

must be done. The CAL.CAL_DUAL bit

controls dual or separate calibration.

The single frequency calibration algorithm

using separate calibration for RX and TX

frequency is illustrated in Figure 34.

In Figure 35 the dual calibration algorithm

is shown for two RX frequencies. It could

also be used for two TX frequencies, or

even for one RX and one TX frequency if

the same VCO current is used.

In multi-channel and frequency hopping

applications the PLL calibration values

may be read and stored for later use. By

reading back calibration values and

frequency change can be done without

doing a re-calibration which could take up

to 25 ms. After a calibration is completed,

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