STW81101 datasheet(20/42 Pages) STMICROELECTRONICS

Part #	STW81101

Description	Multi-band RF frequency synthesizer with integrated VCOs

PDF	42 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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General description

STW81101

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The SERCAL bit should be set to "1" at each division ratio change. It should be noted that in

order to reset the autocalibrator State Machine after a power-up, and anyway before the first

calibration, the INITCAL bit should be set to "1" and back to "0" (this operation is

automatically performed by the Power On Reset circuitry). The calibration takes

approximately 7 periods of the PFD Frequency.

The maximum allowed fPFD to perform the calibration process is 1 MHz. Using an higher

FPFD the following procedure should be adopted:

Calibrate the VCO at the desired frequency with an fPFD less than 1 MHz

Set the A, B and R dividers ratio for the desired fPFD

VCO Voltage Amplitude Control

The bits A0 and A1 control the voltage swing of the VCO. The following table gives the

voltage level expected on the resonator nodes.

Table 8.

Voltage level expected on the resonator nodes

Code A[1:0]

Differential output

voltage (Vp)

1.1

1.3

1.9

2.1

STW81101 Datasheet(PDF) 20 Page - STMicroelectronics