STW82103B Datasheet, PDF (45/67 Pages) STMicroelectronics – RF down converter with embedded integer-N synthesizer

STW82103B
I2C bus interface
9.4
Device calibration through the I²C interface
9.4.1
9.4.2
VCO calibration procedure (I²C interface)
The calibration of the VCO center frequency is activated by setting the SERCAL bit of the
MUTE & CALIBRATION register to ’1’.
To program the device ensuring a correct VCO calibration, the following procedure is
required before every channel change:
1. Program all the Registers using a multi-byte write sequence with the desired setting:
– Functional Mode
– B and A counters
– R counter
– VCO amplitude
– Charge Pump
– Prescaler Modulus
– DAC
– Mixer and LO Control
– all bits of the MUTE & CALIBRATION Register (0x05) set to ’0’.
2. Program the MUTE & CALIBRATION register using a single-byte write sequence (sub-
address 0x05) with the SERCAL bit set to ’1’.
The maximum allowed PFD frequency (F_PFD) to perform the calibration process is 1 MHz. If
the desired F_PFD is higher than 1 MHz the following steps are needed:
3. Perform all the step of the above calibration procedure programming the desired VCO
frequency with a proper setting of R, B and A counter so that F_PFD results lower than
1 MHz.
4. Once calibration is completed, program all the Registers by using a multi-byte write
sequence (Functional Mode, B and A counters, R counter, VCO amplitude, Charge
Pump, Prescaler Modulus, DAC, Mixer and LO Control) with the proper settings for the
desired VCO and PFD frequencies.
Power ON sequence (I²C interface)
At power-on the device is configured in power-down mode.
In order to guarantee correct setting of the internal circuitry after the power on, the following
steps must be followed:
1. Power up the device
2. Provide the Reference clock
3. Implement the first programming sequence with a proper delay time between the STOP
condition of the multi-byte write sequence and that of the single-byte write sequence
(see Figure 20). The T_delay value must respect the following condition:
T_delay > 1023
×
----¹-----
F_ref
F_ref is the reference clock frequency.
Doc ID 018517 Rev 2
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