ST AN2452 Application note

AN2452

Application note

STW8110x evaluation board and graphical user interface

Application and scope

This application note describes the evaluation board (EVB) and the graphical user interface (GUI) of the STW81101, STW81102 and STW81103 multi-band RF frequency synthesizers (with integrated VCOs).

The STW8110x GUI software allows the STW81101, STW81102 and STW81103 synthesizers to be programmed via an I2C/SPI control interface.

Three evaluation boards are available depending on the output matching network optimal frequency range:

■EVB1G (single output - 1 GHz - output divider by 4)

■EVB2G (single output - 2 GHz - output divider by 2)

■EVB4G (single output - 4 GHz - direct output)

February 2008

Rev 3

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www.st.com

Contents	AN2452

Contents

1	Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		3
	1.1	Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	3
	1.2	Main form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	3
	1.3	Tutorial operation mode form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	8
	1.4	Waveform viewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	9

2	Evaluation board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		10
	2.1	Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	10
	2.2	Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	11

2.2.1 Top view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2.2 Bottom view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.3 Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.4 Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.5 Bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

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Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1 Software

1.1Installation

The STW8110x GUI software is built on the Microsoft (R) .NET Framework (see http://www.microsoft.com/net/default.mspx). It may require the installation of the Microsoft

(R) .NET Framework version 2.0, which may require the installation of Windows Installer 3.0 (see http://msdn.microsoft.com/library/default.asp?url=/library/enus/msi/setup/windows_installer_start_page.asp). Administrator privileges are required to install Microsoft (R) .NET Framework and Windows Installer.

Follow these steps to install the STW8110x GUI:

1.If an old version of the GUI is already installed, uninstall it.

2.Run setup.exe (datasheets, programming configuration files and desktop/quick launch shortcuts are optional components installed by default).

3.Run STW8110xGUI.exe

4.The default starting operation mode is Tutorial. The starting operation mode can be modified by means of the radio buttons in the tutorial form:

a)Tutorial: a brief tutorial on the features of the GUI.

b)Basic: only the main options are enabled.

c)Advanced: all the available options are enabled.

1.2Main form

This section details the items on the main form. See Figure 1: Main form on page 4.

1.Pressing this button shows the About STW8110xGUI screen.

2.Pressing this button opens the datasheet of the selected device.

3.Help

4.Device selection (STW81101/2/3).

5.GUI operation modes:

Tutorial: A brief tutorial on the basic features of the GUI. An inner default configuration is loaded.

Basic: only the main options are enabled. Frequency values must be set in the following order:

a)Input reference frequency Fref.

b)Output frequency step Fstep.

c)Output frequency Fout.

The calibrator is always ON. VCO and output divider are set automatically.

Advanced: all the available options are enabled. Any Fvco or Fout are allowed. A message will warn if the inserted values are beyond the frequency limits of the VCOs.

Frequency values must be set in the following order:

a)Input reference frequency Fref.

b)Output frequency step Fstep or Fpfd.

c)Output frequency Fout or Fvco.

Waveform Viewer: a form is opened displaying the bit sequence sent to the device.

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Software					AN2452
Figure 1. Main form
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6.Swallow counter A: 5-bit counter.

7.VCO calibrator:

–Last calibration Fvco: contains the last calibration data (VCO and frequency of calibration).

–Calibrator ON/OFF.

–The maximum allowed Fpfd during calibration is 1 MHz. If Fpfd > 1 MHz, the device is programmed in two steps:

a)Device is programmed forcing calibration with the maximum Fpfd ≤1 MHz (Fpfd = Fref / R ≤1 MHz ==> R ≥ Fref / 106).

b)Device is programmed with the desired Fpfd.

Example with Fref = 76.8 MHz:

Desired values:

-Fpfd = 1200 kHz

-R = Fref / Fpfd = 64 Forced values:

-R' = Fref / 106 = 76.8 = 77

-F'pfd = Fref / R' = 997.403 kHz Device programming in two steps:

a)Device is programmed with Fpfd = 997.403 kHz and Calibrator ON.

b)Device is programmed with Fpfd = 1200 kHz and Calibrator OFF.

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8.Output divider:

–Direct output.

–Divider by 2.

–Divider by 4.

9.Configurations:

–Load/Save: load/save a configuration file.

–Load default/Save default: load/save a default configuration.

10.Program counter B: 12-bit counter.

11.VCO. VCO settings:

–Output frequency range/VCOs frequency range: press this button to show information on the limits of Fout/Fvco (only for the embedded VCOs).

–VCO selection (enabled only in Advanced mode):

-EXT: external VCO. The external VCO buffer is able to manage a signal coming from an external VCO in order to build a synthesizer using the STW8110x only as PLL IC. The external VCO signal can range from 625 MHz up to 5 GHz. Its minimum power level must be -10 dBm.

-VCO A/VCO B: embedded VCOs.

12.Parallel port address. Hex value of the parallel port base address:

–278: normally assigned to LPT2.

–378: normally assigned to LPT1.

–3BC

–FILE: output is saved to a text file.

13.Prescaler modulus:

–P=16

–P=19

14.Reference divider. The 10-bit programmable reference counter allows the input reference frequency to be divided to produce the input clock to the phase frequency detector (PFD):

Fpfd = Fref / R

where

–Fpfd: PFD input frequency

–Fref: input reference frequency

Limits: 2 ≤R ≤1023

15.Frequency settings:

–Fref: input reference frequency (MHz) - Limits: 10 MHz ≤Fref ≤200 MHz

–Fpfd: phase frequency detector (PFD) input frequency (kHz) Fpfd = Fref / R, where R is the reference divider factor.

–-/+: finds a lower/higher rational value for Fpfd.

–Fvco: VCO oscillating frequency (MHz)

Fvco = N · Fpfd.

–N: PLL division ratio N = B · P + A.

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16.Output frequency settings:

–Fout: output frequency (MHz)

Fout = Fvco / DIV, where DIV is the output division ratio.

–Fstep: output frequency step (kHz)

Fstep = Fpfd / DIV, where DIV is the output division ratio.

–-/+: finds a lower/higher rational value for Fstep.

17.Charge pump current. The nominal value of the output current is controlled by an

external resistor (Rext) and can be varied over 8 levels by means of 3 dedicated programming bits:

–CPSEL[2:0]: bits controlling the charge pump current

–Rext: the minimum value of the current is: Imin = 2 Vbg / Rext where Vbg = 1.17 V.

–Icp: charge pump current (mA) Icp = (CPSEL + 1) · Imin

18.VCO voltage amplitude. The voltage swing of the VCOs can be adjusted over 4 levels by means of two dedicated programming bits:

–PLL_A[1:0]: bits controlling the voltage swing of the VCO.

This setting trades current consumption with the VCO’s phase noise performances. Higher amplitudes provide better phase noise, whereas lower amplitudes save power.

19.Two digital interfaces are available:

–I2C

-ACK: if checked and the acknowledge is not received, read and write operations fail. Uncheck this if the board is not enabled to read.

-Read: read the read-only register.

-Write: write the 6 write-only registers.

-A[2:0]: the device address (1100A2A1A0) must be set.

–SPI

Show sent data: the programming sequence is shown on the message list.

20.Device programming:

–Device programming modes:

-Device ON: device on with output buffer control disabled.

-Out Buffer CTRL: device on with output buffer control enabled. This control mode allows to enable/disable the output stage by a hardware control pin (EXT_PD, pin 23) while the PLL stays locked at the desired frequency; in such a way a very fast switching time is achieved. This feature can be useful in designing a ping-pong architecture saving the cost of an external RF switch.

-Power Down: 'Power Down' mode enabled (device off).

–SEND: press this button to program the device.

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21.Message list: displays information, warnings and errors:

– CLEAR: press this button to delete all the messages.

Clicking the right mouse button on the message list shows a menu:

–Copy: copy the selected messages to the clipboard.

–Copy to File: copy the selected messages to a file.

–Append Mode: file is opened in append mode when 'Copy to File' is used.

–Select All: all messages are selected (double-clicking the left mouse button has the same effect).

–Deselect All: no message is selected.

–Clear after Send: clears the message list after pressing the Send button.

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