Texas Instruments TRF3762 EVM User manual

1 Hardware Setup
User's GuideSLWU056 – June 2008
TRF3762 EVM User's Guide
Contents1 Hardware Setup .............................................................................................................. 12 Software Setup ............................................................................................................... 2Appendix A Synthesizing Desired Frequencies ............................................................................. 10Appendix B Output Configuration Options ................................................................................... 11Appendix C TRF3762 QFN Installation Using a Hakko Hot Air Rework Station ........................................ 12
List of Figures
1 Single Output Without Balun .............................................................................................. 2
List of Tables
1 Required Test Hardware .................................................................................................... 1
This manual can help users to operate the TRF3762 evaluation module (EVM) with the supplied software.The required hardware for testing the EVM is listed in Table 1 .
Table 1. Required Test Hardware
Hardware Specifications Units
Power supply (1) 4.5 to 5.2 VSpectrum analyzer (1) 0 to 6 Spurs GHz–160 resolution (phase noise) dBmAgilent’s 5052 (1)Low phase noise reference source (1) 1 kHz –120.22 dBc100 kHz –145.6590 kHz –1581 MHz –1583 MHz –1605 MHz –161Rms jitter 236.69 psPersonal computer (PC) (1) 2-GHz processor, CD drive, Parallel portPower cable (1) Supplied by Texas InstrumentsParallel-to-parallel connector cable(1) Not supplied by Texas Instruments DB25 to DB25Coaxial cable (2) 50 Ω
X-ACTO is a trademark of Elmer's Products, Inc..LabVIEW is a trademark of National Instruments Corporation.
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Single ended RF out
To spectrum analyzer or Agilent 5052
DB25 TO PC
DC input for
Open loop test
Reference input
To low phase noise
Reference.
Power supply
Connection
To power supply.
Differential RF out
Not connected.
2 Software Setup
Software Setup www.ti.com
To achieve the test data, all hardware that is supplied with EVM is required. TRF3762 measuredperformance depends on the phase noise characteristics of the reference source used as well as theresolution of the hardware used for phase noise measurements.
The setup of the device is simple. See Figure 1 .
Figure 1. Single Output Without Balun
The board shown in Figure 1 has a 3-dB lower output power when configured as a single-ended output,approximately 0 dBm. When converting to a differential output by removing the 50- Ωresistor R32 in thedifferential path the output power should increase by 3-dB minus the balun losses. Components can beadded to achieve a tuned reactive load which improves the output power. See Appendix B for outputconfiguration options.
The following items are provided in the TRF3762EVM kit.•CD-ROM
•EVM board•Power cable•Programming cable
The LabVIEW™ software provided by Texas Instruments on the accompanying CD is the software thatconfigures the TRF3762. It is used to set the registers inside the device for normal operation. TheLabVIEW software interfaces to the EVM via a DB25 connector. The chip uses a SPI interface protocolwith data formatted as little endian, which means the LSB is clocked in first.
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2.1 Software Installation
Or
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When loaded, the CD that accompanies the EVM displays on the PC monitor either a folder with a date fora file name or the full folder of files.
In either case, find the installer folder. This is the folder containing the program and its support files. Oncefound, open the installer folder, and the following screen displays.
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Software Setup www.ti.com
TI recommends that all files in the installer folder be copied to one folder on the PC or laptop that will berunning the program before installing it. Do this by clicking on the installer folder and dragging it to the PC.
Once the folder installer has been copied on the computer, open it and find the LabVIEW runtime enginesetup.exe file. Double-click it ,and execute the program by following the on-screen prompts.
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C:\Customers Computer
New folder
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Once the LabVIEW runtime engine is installed, go back to the installer folder and create a folder calledaccessHW.
Open the accessHW.zip file. This file contains the software to set up the port on the PC.
Extract all files in the zip folder to the folder you created ( accessHW). The files should look like thefollowing.
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Software Setup www.ti.com
Double-click on the setup.exe file, and run the setup of the port. You are prompted for which object orlibrary to use.
Select Microsoft Visual C++ 2x, 4x, and then click Next. Follow the prompts.
Once the program is installed, open it and you should see the following display.
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This is the main control screen to use for programming the TRF3762; the frequency of interest is underthe tab labeled Top Level App.
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2.2 The Controls
’
Use the spinner buttons to adjust the divide by ratio.
Type in the value of R27 on the board.
Make sure this button ’s indicator is green.
Make sure this buttons indicator is green.
Type in the frequency of your reference in MHz.
Type in the step frequency you require.
Use the spinner buttons to set.
Type in the frequency of interest.
Use spinner buttons to change the frequency divider.
Use execute button to run program.
Shows the output frequency of TRF3761
Software Setup www.ti.com
The left side of the main control screen is where inputs can be adjusted.
•Fcrystal is the reference used on the EVM. It can between 10 MHz to 104 MHz.•Fpfd is the phase frequency detector frequency and sets the frequency step size. For example, if themain frequency is 2000 MHz and the Fpfd is 200 kHz, then the next frequency step can be 2000.2MHz.
•Prescalar Div Ratio is the ratio used in the Fout equation, Fout = Fpfd (A+PB), where the numerator ofthe Prescalar Div Ratio is equal to P, and A and B are calculated. For more information, see AppendixA.•Rbias is used for a calculation which is on the right side of the Main Control Screen in the windowIcp(Rbias).The value of Rbias is set to the same value as R27 on the EVM board is 2.73 k Ω. Theresistor value can be changed on the board if a different charge pump current is desired.•Icp sets the amount of current on the charge pump as well. Eight setting are used to increase anddecrease the current; they are 0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9, and 5.6. These numbers represent thecurrent seen if a 4.75-k Ωresistor is used. The calculation to determine the desired Icp
actual
is[Icp(4.75k)]/Rbias = Icp
actual
, which should give the same answer as the Icp(Rbias) on the right sidecalculations.
•Fvco is the output frequency of VCO.•Output Mode sets the frequency divider. For example, if 500 MHz is required, then set the Fvco to2000 MHz and the Output Mode to “/4”.•The Selected Output window at the bottom by the Execute button shows the output frequency that theuser sets up.•To enter the data into the TRF3762, press the Execute button. Once pressed, the output changes tothe frequency shown in the Selected Output window.
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2.3 The Calculations
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The right side of the main control screen shows the system setup calculations.
•FREF is the reference oscillator frequency in MHz.•Fref_Frac is not used.•RDIV is the number the reference frequency is divided by to get Fpfd.•NDIV is the number the output frequency is divided by to get Fpfd.•A and B are the variables in the equation Fout = Fpfd (A+PB) as discussed in the prescalar section ofthe controls. See Appendix A.•Fout is the actual frequency out.•Fvco 1x is the undivided frequency out of the VCO.•Fvco DIV2 is the frequency out of the VCO divided by 2.•Fvco DIV4 is the frequency out of the VCO divided by 4.•Spur offset is the offset of the phase frequency detector spur.•Icp (Rbias) is the actual current of the charge pump. Calculated from [Icp(4.75k)]/Rbias = Icp
actual
.
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Appendix A Synthesizing Desired Frequencies
Appendix A www.ti.com
Prescalar Div is a multiselection dual modulus to limit the frequency of the Prescalar to below 250MHz. The setting are 8/9, 6/17, 32/33, and 64/65. The TRF3762 has an integer-N PLL synthesizer,and because of its flexibility (14-bit R, 6-bit A, 13-bit B counter, and dual modulus prescalar), isideal for synthesizing virtually any desired frequency. Assume that one needs to synthesize a900-MHz local oscillator, with spacing capability (minimum frequency increment) of 200 kHz, as in atypical GSM application. The choice of the external reference oscillator to be used is beyond thescope of this user's guide, but assuming that a 10-MHz reference is selected, one can calculate thesettings that yield the desired output frequency and channel spacing. Although more than onesolution can often apply to a specific set of conditions, the following is one means of achieving thedesired result.
First, select the appropriate R counter value. Because a channel spacing of 200 kHz is desired, thePFD can also be set to 200 kHz. Calculate the R value through R = REFIN/PFD = 10 MHz/ 200kHz = 50. Assume that a prescalar value of 8/9 is selected. This is a valid choice because theprescalar output will be well within the 200-MHz limit (900 MHz / 8 = 112.5 MHz). Select theappropriate A and B counter values. It is known that RFOUT = Fpfd ×N = (F
REFIN
/ R) ×(A + P ×B). Therefore, solve the following equation:900 MHz = 200 kHz x (A + 8 x B)
Clearly, many solutions exist for this single equation with two unknowns; however, because 3 ≤B≤8191, and also B ≥A, there are some basic constraints on the solution. So, if A = 4, solving theequation yields B = 562. Thus, one complete solution would be to choose: R = 50, A = 4, B = 562,and P = 8/9, resulting in the desired N = 4500.
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