ST AN2455 Application note

AN2455

Application note

STWPLLSim phase noise and settling time simulator for STW8110x

Application and scope

The STWPLLSim tool helps the end user to design the optimal loop filter for the STW81101x synthesizers. It provides a very accurate estimation of the overall phase noise and settling time performances, allowing the user to interactively compare measurements with simulated performance.

July 2007

Rev 2

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www.st.com

Installation	AN2455

1 Installation

The STWPLLSim software is written in Java and designed to run on Windows 2000/XP. To perform time domain simulations, STWPLLSim requires the MATLAB Component Runtime (MCR) Libraries (Copyright 1984-2005, The MathWorks, Inc. See http://www.mathworks.com/access/helpdesk/help/toolbox/compiler/index.html?/access/help desk/help/toolbox/compiler/f12-999353.html).

Run SETUP.bat to install STWPLLSim.

2 Main form

Figure 1. STWPLLSim: main form and project flow

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2.1Creating and managing projects

New and Open buttons allow the user to create a new project or to open an existing one.

The project can be saved by pressing the Save / Save As buttons.

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AN2455	Main form

2.2Project flow

These are the steps to follow in using STWPLLSim, as shown in Figure 1:

1.Main settings (see the screenshot in Figure 2):

a)Device choice (STW81101, STW81102, STW81103)

b)Output frequency [MHz]

c)Frequency step [kHz]

d)Output stage (direct output, divider by 2, divider by 4)

e)VCO and phase detector frequencies are calculated from the inserted data.

f)A table helps to choose the correct output stage depending on the desired output frequency and the selected device.

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Main form	AN2455

Figure 2. Main settings

1a

1b

1c

1d

1e

1f

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AN2455	Main form

2.Prescaler: select the prescaler (either 16/17 or 19/20).

3.Reference clock (see the screenshot in Figure 3):

a)Reference frequency

b)Fitting parameters for phase noise performance

Figure 3. Reference clock settings

3a

3b

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