Single-Chip Low Power RF Transceiver for Narrowband Systems ...

BUFF_CURRENT Register (19h)
REGISTER NAME Default
value
Active Description
BUFF_CURRENT[7: 6] PRE_CURRENT[1:0] 1 - Prescaler current scaling
0: Nominal current
1: 2/3 of nominal current
2: 1/2 of nominal current
3: 2/5 of nominal current
CC1021
BUF F_CURRENT[5:3] RX_CURRENT[2:0] 4 -
Recommended setting:
PRE_CURRENT=0.
LO buffer current,
in RX (to mixers)
0: Minimum buffer current
…
7: Maximum buffer current
BUFF_CURRENT[2:0] TX_CURRENT[2:0] 5 -
Recommended setting: RX_CURRENT=4.
LO buffer current, in TX (to PA driver)
0: Minimum
buffer current
…
7: Maximum buffer current
Recommended settings:
TX_CURRENT=2 for 402-470 MHz,
TX_CURRENT=5 for 804-940 MHz.
PLL_BW Register (1Ah)
REGISTER NAME Default
value
Active Description
PLL_BW[7:0] PLL_BW[7:0] 134 - Charge pump current scaling/rounding
factor.
Used to calibrate charge pump current
for the
desired PLL loop bandwidth. The value is given by:
PLL_BW = 174 + 16 log2(fref/7.126) where fref is the
reference frequency in MHz.
CALIBRATE Register (1Bh)
REGISTER NAME Default
value
Active Description
CALIBRATE[7] CAL_START 0 ↑ ↑ 1: Calibration
started
0: Calibration inactive
CALIBRATE[6] CAL_DUAL 0 H Use calibration results for both fr equency A and B
0: Store results
in A or B defined by F_REG (MAIN[6])
1: Store calibration
results in both A and B
CALIBRATE[5:4] CAL_WAIT[1:0] 0 - Selects calibration wait time (affects
accuracy)
0 (00): Calibration time is approx. 90000 F_REF
periods
1 (01): Calibration time is approx. 110000 F_REF periods
2 (10): Calibration time is approx. 130000 F_REF periods
3 (11): Calibration time is approx. 200000 F_REF periods
CALIBRATE[3] - 0 -
Recommended setting: CAL_WAIT=3 for best accuracy in
calibr ated PLL loop filter bandwidth.
Rese rved,
write 0
CALIBRATE[2:0] CAL_ITERATE[2:0] 5 - Iteration start value for calibration DAC
0 (000): D AC start value 1, VC