National Semiconductor LMX2531LQ1515E Скачать руководство пользователя страница 7 | Manualshive

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National Semiconductor LMX2531LQ1515E Скачать руководство пользователя страница 7

L M X 2 5 3 1 L Q 1 3 1 2 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S

Free-Running VCO Phase Noise (Internal Divide by 2 Enabled)

Fout = 725 MHz (1450 MHz/2)

Fout = 707.5 MHz (1515 MHz/2)

Fout = 6790 MHz (1580 MHz/2)

The plots to the left show the true phase noise capability of the

VCO. In order to take these plots, the E5052 phase nose

analyzer was used. The method was to lock the PLL to the

proper frequency, then disable the EN_PLL, EN_PLLLDO1, and

EN_PLLLDO2 bits. The equipment needs to be able to track

the VCO phase noise to measure in this way, and one can not

let the VCO drift too far off in frequency. If this kind of equipment

is not available, the VCO phase noise can also be measured by

making a very narrow loop bandwidth filter.

When divide by 2 is enabled, the phase noise at lower offsets is

about 6 dB better. At high offsets, the overall phase noise

improvement may be lower because the divider is noise floor is

adding to the phase noise.

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Содержание LMX2531LQ1515E

Страница 1: ...X2531LQ1515E Evaluation Board Operating Instructions National Semiconductor Corporation Timing Devices Business Group 10333 North Meridian Suite 400 Indianapolis IN 46290 LMX2531LQ1515EFPEB Rev 4 02 2008 ...

Страница 2: ...DIVIDE BY 2 DISABLED 6 FREE RUNNING VCO PHASE NOISE INTERNAL DIVIDE BY 2 ENABLED 7 FRACTIONAL SPURS INTERNAL DIVIDE BY 2 DISABLED 8 FRACTIONAL SPURS INTERNAL DIVIDE BY 2 ENABLED 9 INTEGER SPURS INTERNAL DIVIDE BY 2 DISABLED 10 INTEGER SPURS INTERNAL DIVIDE BY 2 ENABLED 11 CODELOADER SETTINGS 12 SCHEMATIC 17 BILL OF MATERIALS 18 TOP LAYER 19 MID LAYER 1 GROUND PLANE 20 MID LAYER 2 POWER 21 BOTTOM L...

Страница 3: ...tors tend to be very noisy and should be used with caution If a signal generator is used the signal generator phase noise contribution can be reduced by setting the signal to 80 MHz and dividing this down to a phase detector frequency of 10 MHz Set up the CodeLoader software o Select the proper part from the menu as Select Part PLL VCO LMX2531LQ1515E o Select the proper mode from the Mode menu o L...

Страница 4: ...is used ensure that the RF is set to ON If using the lower frequency band DIV2 1 the VCO frequency in CodeLoader should be twice the frequency at the Fout pin Ensure the VCO FREQUENCY CAL bits on the Bits Pins tab are correct Ensure the loop filter is optimized if the charge pump current phase detector frequency or loop filter values have been changed from their original settings Ensure the integr...

Страница 5: ... 3 1 2 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Phase Noise Output Frequency 1515 MHz Internal Divide by 2 Disabled DIV2 0 Output Frequency 757 5 MHz Internal Divide by 2 Enabled DIV2 1 5 ...

Страница 6: ...of the VCO In order to take these plots the E5052 phase nose analyzer was used The method was to lock the PLL to the proper frequency then disable the EN_PLL EN_PLLLDO1 and EN_PLLLDO2 bits The equipment needs to be able to track the VCO phase noise to measure in this way and one can not let the VCO drift too far off in frequency If this kind of equipment is not available the VCO phase noise can al...

Страница 7: ...was to lock the PLL to the proper frequency then disable the EN_PLL EN_PLLLDO1 and EN_PLLLDO2 bits The equipment needs to be able to track the VCO phase noise to measure in this way and one can not let the VCO drift too far off in frequency If this kind of equipment is not available the VCO phase noise can also be measured by making a very narrow loop bandwidth filter When divide by 2 is enabled t...

Страница 8: ...Spur at 250 kHz offset at a worst case frequency of 1450 25 MHz is 72 7 dBc Worst case channels occur at exactly one channel spacing above or below a multiple of the crystal frequency Fractional Spur at 250 kHz offset at a worst case frequency of 1520 25 MHz is 69 4 dBc Fractional Spur at 250 kHz offset at a worst case frequency of 1570 25 MHz is 77 7 dBc 8 ...

Страница 9: ... MHz is 80 4 dBc Since this mode uses the divide by 2 mode the channel spacing here is actually 125 kHz The spur at 125 kHz could be eliminated by doubling the channel spacing before the divider Spur at 250 kHz offset for a frequency of 615 125 MHz is 85 7 dBc Spur at 250 kHz offset for a frequency of 630 125 MHz is 84 5 dBc The sub fractional spur at 125 kHz offset of 79 dBc is also visible 9 ...

Страница 10: ... T R U C T I O N S Integer Spurs Internal Divide by 2 Disabled Spur at 10 MHz offset for a frequency of 1450 MHz is 83 7 dBc Spur at 10 MHz offset for a frequency of 1520 MHz is below the spectrum analyzer noise floor Spur at 10 MHz offset for a frequency of 1580 MHz is 92 0 dBc 10 ...

Страница 11: ...rs Internal Divide by 2 Enabled Spur at 10 MHz offset for a frequency of 725 MHz is below the spectrum analyzer noise floor Spur at 10 MHz offset for a frequency of 707 5 MHz is below the spectrum analyzer noise floor Spur at 10 MHz offset for a frequency of 790 MHz is below the spectrum analyzer noise floor 11 ...

Страница 12: ... 1 2 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S CodeLoader Settings CodeLoader is designed to run many devices When CodeLoader is first started it is necessary to select the correct device 12 ...

Страница 13: ...menu This restores bit settings and frequencies but not the Port Setup information The default reference oscillator used for these instructions was 10 MHz but there is an alternate mode for a 61 44 MHz oscillator as well If the bits become scrambled their original state may be recalled by choosing the appropriate mode If the internal divide by 2 DIV2 is enabled the VCO frequency will not change 13...

Страница 14: ...y bit to view more information about what this does When the DIV2 bit is enabled the frequency from the part will be half of that shown on the PLL VCO tab The frequency on the PLL VCO tab does not reflect this because the divide by 2 is actually after the VCO Also be sure to load the device Ctrl L after changing this bit to allow the VCO to calibrate for optimal phase noise performance 14 ...

Страница 15: ...N S The Registers tab shows the literal bits that are being sent to the part These are the registers every time the PLL is loaded by using the menu command or Ctrl L R5 INIT1 and R5 INIT 2 are just the R5 register being used to properly initialize the part So a single Ctrl L will load the part 15 ...

Страница 16: ... S T R U C T I O N S The port setup tells CodeLoader what information goes where If this is wrong the part will not program Although LPT1 is usually correct CodeLoader does NOT automatically detect the correct port On some laptops it may be LPT3 Manual verification is required 16 ...

Страница 17: ... C1 R2 C12 C2 VccVCO VccDIG VccPLL VccBUF R3 C3 C17 R4 C9 C4 R5 C5 OSCin VccVCO VccPLL VccBUF C13 C18 C20 R7 R23 R22 Ftest LD C15 C22 R1 R9 TRIGGE R GND 1 2 3 4 5 6 7 8 POWER C24 C14 C11 C19 C21 C23 Notethat AnyComponent w ithDesignator 100or Higheris ontheBottomSideof theBoard C10 VccDIG 1 NC 2 GND 3 NC 4 NC 5 VregBUF 6 NC 7 DATA 8 CLK 9 LE 10 CE 11 NC 12 NC 13 NC 14 NC 15 VccVCO 16 Vr egVCO 17 V...

Страница 18: ...Ω R1 R18 10 4 Vishay CRCW060310R0JNEA 603 5 0 1W Thick Film 10Ω R2 R3 R4 R5 11 1 Vishay CRCW060351R0JNEA 603 5 0 1W Thick Film 51Ω R6 12 1 Vishay CRCW060310K0JNEA 603 5 0 1W Thick Film 1KΩ R2_LF 13 4 Vishay CRCW060310K0JNEA 603 5 0 1W Thick Film 10KΩ R9 R11 R13 R15 14 4 Vishay CRCW060312K0JNEA 603 5 0 1W Thick Film 12KΩ R10 R12 R14 R16 15 1 Comm Con Connectors HTSM3203 8G2LF 2X4 n a n a Metal Plas...

Страница 19: ...L M X 2 5 3 1 L Q 1 3 1 2 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Top Layer 19 ...

Страница 20: ...L M X 2 5 3 1 L Q 1 3 1 2 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Mid Layer 1 Ground Plane 15 Mils Down FR4 20 ...

Страница 21: ...L M X 2 5 3 1 L Q 1 3 1 2 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Mid Layer 2 Power 21 ...

Страница 22: ...L M X 2 5 3 1 L Q 1 3 1 2 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Bottom Layer Signal Note Total Board Thickness 61 mils 22 ...

Страница 23: ...L M X 2 5 3 1 L Q 1 3 1 2 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Top Build Diagram 23 ...

Страница 24: ...for use in safety critical applications such as life support where a failure of the TI product would reasonably be expected to cause severe personal injury or death unless officers of the parties have executed an agreement specifically governing such use Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications and acknowledge and agre...

Страница 25: ...Mouser Electronics Authorized Distributor Click to View Pricing Inventory Delivery Lifecycle Information Texas Instruments LMX25311515EVAL LMX25311515EVAL NOPB ...

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