STW81103 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

MFG CO.

STW81103

Multi-band RF frequency synthesizer with integrated VCOs

STMicroelectronics 

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STW81103

I2C bus interface

6.4

6.4.1

VCO calibration procedure

Calibration of the VCO center frequency is activated when the SERCAL bit (CALIBRATION

register bit[6]) is set to 1.

To program the device properly while ensuring VCO calibration, perform the following steps

before every channel change:

1. Program all the registers using a multi-byte write sequence with the desired settings

(functional mode, B and A counters, R counter, VCO amplitude, charge pump,

prescaler modulus), and all the bits of the CALIBRATION register (05H) set to 0.

2. Program the CALIBRATION register using a single-byte write sequence (subaddress

05H) with the SERCAL bit set to 1.

The maximum allowed PFD frequency (FPFD) during calibration is 1 MHz; if you want a FPFD

higher than 1 MHz, perform the following additional steps:

● Perform all the steps of the calibration procedure, making sure to program the desired

VCO frequency with proper settings for the R, B and A counters so that FPFD is ≤1 MHz.

● Program the device with the desired VCO and PFD frequency settings according to

step 1) above.

VCO calibration auto-restart feature

The VCO calibration auto-restart feature can be enabled in two steps:

1. set the desired frequency ensuring VCO calibration as described above (section 6.4)

2. program the FUNCTIONAL_MODE register (sub-address 00H) using a single-byte

write sequence with the CAL_AUTOSTART_EN bit set to '1' while keeping unchanged

the others.

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