National Semiconductor LMX2531LQ3010E Скачать руководство пользователя | Manualshive

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L M X 2 5 3 1 L Q 3 0 1 0 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

Far-out Phase noise is worse than evaluation board instructions

show

•

Ensure the measurement equipment noise floor is not limiting the measurement. For

spectrum analyzers, the noise floor at a particular setting can be measured by removing the
RF input signal

•

If the settings are changed from what the board was designed for, ensure the delta-sigma
modulator is not increasing the far-out noise. To determine this, tune to an integer channel
and set the ORDER bit to “Reset Modulator”. The far out phase noise should not decrease. If
it does, try a loop filter with more attenuation or select a lower order delta-sigma modulator.

Device Data

The next few pages show data collected from the LMX2531LQ3010 evaluation board.

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Содержание LMX2531LQ3010E

Страница 1: ...Q3010E Evaluation Board Operating Instructions National Semiconductor Corporation Timing Devices Business Group 10333 North Meridian Suite 400 Indianapolis IN 46290 LMX25313010EVAL Instructions Rev 6...

Страница 2: ...VCO PHASE NOISE INTERNAL DIVIDE BY 2 DISABLED 7 FREE RUNNING VCO PHASE NOISE INTERNAL DIVIDE BY 2 ENABLED 8 FRACTIONAL SPURS INTERNAL DIVIDE BY 2 DISABLED 9 FRACTIONAL SPURS INTERNAL DIVIDE BY 2 ENAB...

Страница 3: ...the OSCin pin Typically the 10 MHz output from the back of the RF test equipment is a good source Signal generators tend to be very noisy and should be used with caution If a signal generator is used...

Страница 4: ...tion with the board Ensure the Green LEDs are lit on the USB board Ensure there are no conflicts with other USB devices and reinstall the board Part responds to programming but does not lock to the co...

Страница 5: ...ing can be measured by removing the RF input signal If the settings are changed from what the board was designed for ensure the delta sigma modulator is not increasing the far out noise To determine t...

Страница 6: ...0 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 3010 25 MHz Internal Divide by 2 Disabled DIV2 0 Output Frequency 1505 125 MHz Internal Divide...

Страница 7: ...s 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 EN_PLLLDO2 EN_DIGLDO and EN_OSC bits The equipment needs to be able t...

Страница 8: ...the EN_PLL EN_PLLLDO1 EN_PLLLDO2 EN_DIGLDO and EN_OSC 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...

Страница 9: ...low a multiple of the crystal frequency The 71 8 dBc fractional spur at 250 kHz offset is at a worst case frequency of 3010 25 MHz The 74 9 dBc sub fractional spur at 125 kHz offset is also visible Wo...

Страница 10: ...requency of 1455 125 MHz The 77 8 dBc sub fractional spur at 125 kHz offset is also visible The 73 1 dBc fractional spur at 250 kHz offset is at a worst case frequency of 1505 125 MHz The 77 6 dBc sub...

Страница 11: ...I O N S Integer Spurs Internal Divide by 2 Disabled The integer spur at 10 MHz offset at an Fout frequency of 2910 MHz is 84 2 dBc The integer spur at 10 MHz offset at an Fout frequency of 3010 MHz is...

Страница 12: ...I O N S Integer Spurs Internal Divide by 2 Enabled The integer spur at 10 MHz offset at an Fout frequency of 1455 MHz is 84 3 dBc The integer spur at 10 MHz offset at an Fout frequency of 1505 MHz is...

Страница 13: ...46 0 dBc ORDER 4th Order Modulator Fractional numerator 500 Fractional denominator 1 000 000 The In band fractional spur at 5 kHz offset at an Fout frequency of 3010 005 MHz is 31 2 dBc ORDER 4th Ord...

Страница 14: ...46 3 dBc ORDER 4th Order Modulator Fractional numerator 500 Fractional denominator 1 000 000 The In band fractional spur at 5 kHz offset at an Fout frequency of 1505 0025 MHz is 39 0 dBc ORDER 4th Ord...

Страница 15: ...025 MHz 1510 MHz 10 MHz 151 which is a multiple of the FPD 1510 0025 MHz is the divided output frequency Therefore a spur will occur at 2 5 kHz offset 1510 0025 1510 MHz If the frequency was set to 15...

Страница 16: ...1 0 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 Select Device CodeLoader runs many devices When CodeLoader is first started it is necessary to select...

Страница 17: ...ode can be recalled easily from the menu This restores bit settings and frequencies but not the Port Setup information For the CodeLoader program the default reference oscillator used for these instru...

Страница 18: ...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 Bits Pins The Bits Pins tab displays many of the bits used to program the part Right mouse click any bit to view more informati...

Страница 19: ...Counter Phase Detector Frequency N Counter and Charge Pump Gain should be set to provide the desired output frequency with an optimized loop filter The desired VCO frequency may also be entered direc...

Страница 20: ...gisters 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 jus...

Страница 21: ...I N G I N S T R U C T I O N S Port Setup 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 au...

Страница 22: ...R7 R23 R22 Ftest LD C15 C22 R1 R9 TRIGGER GND 1 2 3 4 5 6 7 8 POWER C24 C14 C11 C19 C21 C23 NotethatAnyCom ponentw ithDesignator 100or Higher isontheBottomSideoftheBoard C10 Vcc Vcc R18 R24 R17 C105 C...

Страница 23: ...R20 9 2 Panasonic P 22AHCT ND 603 10 0 1W Thick Film 0 22 R22 R23 10 2 Vishay CRCW06033R3JRT1 603 5 0 1W Thick Film 3 3 R1 R18 11 4 Vishay CRCW0603100JRT1 603 5 0 1W Thick Film 10 R2 R3 R4 R5 12 1 Vis...

Страница 24: ...L M X 2 5 3 1 L Q 3 0 1 0 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 24...

Страница 25: ...L M X 2 5 3 1 L Q 3 0 1 0 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 below top FR4 layer 25...

Страница 26: ...L M X 2 5 3 1 L Q 3 0 1 0 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 26...

Страница 27: ...L M X 2 5 3 1 L Q 3 0 1 0 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 27...

Страница 28: ...L M X 2 5 3 1 L Q 3 0 1 0 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 28 Top Build Diagram...

Страница 29: ...or 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...

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