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REFERENCE CLOCK: application on Sysol ME and Dragon Fly VYn_ps12660 CS - Philips Semiconductors Le Mans
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Philips Semiconductors, Costumer Support, 04/12/20032 Introduction: Importance of the reference clock Reference clock: Motor of the mobile All mobile functions depend on it Bad reference clock’s performances means bad mobile’s performances
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Philips Semiconductors, Costumer Support, 04/12/20033 Training Content: Reference clock presentation Reference clock contents Reference clock on Sysol ME Reference clock working on Sysol ME Reference clock performances to check Problems linked to reference clock Reference clock on Dragon Fly
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Philips Semiconductors, Costumer Support, 04/12/20034 Training Content: Reference clock presentation Reference clock contents Reference clock on Sysol ME Reference clock working on Sysol ME Reference clock performances to check Problems linked to reference clock Reference clock on Dragon Fly
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Philips Semiconductors, Costumer Support, 04/12/20035 REFERENCE CLOCK PRESENTATION
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Philips Semiconductors, Costumer Support, 04/12/20036 Heart of the mobile:
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Philips Semiconductors, Costumer Support, 04/12/20037 For Base-Band: - Clock for processor - Generation of all clocks
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Philips Semiconductors, Costumer Support, 04/12/20038 For the Radio part: Reference clock for the synthetisers (PLL) With Fout= N x Fref
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Philips Semiconductors, Costumer Support, 04/12/20039 In Sysol 2
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Philips Semiconductors, Costumer Support, 04/12/200310 Frequency of the reference clock Fref = N x 13 MHz For ALL GSM mobiles 13000 kHz/48 = 270.833 kbits/s 48 clock cycle = 1 time bit 12 clock cycle = 1 quarter bit (time unity in mobiles) System clock must allow to have complete quarter bits. It is this with 3.25, 6.5, 13, 26 MHz
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Philips Semiconductors, Costumer Support, 04/12/200311 Training Content: Reference clock presentation Reference clock contents Discrete or integrated Reference clock on Sysol ME Reference clock working on Sysol ME Reference clock performances to check Problems linked to reference clock Reference clock on Dragon Fly
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Philips Semiconductors, Costumer Support, 04/12/200312 REFERENCE CLOCK CONTENTS
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Philips Semiconductors, Costumer Support, 04/12/200313 Reference clock purpose: Provide a sinusoidal signal with a stable frequency of Nx13 MHz: No square waves generator 32 kHz of BB is not enough - Not enough stable - Can’t provide easily Nx13 MHz
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Philips Semiconductors, Costumer Support, 04/12/200314 Use of a Crystal-based oscillator
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Philips Semiconductors, Costumer Support, 04/12/200315 Description of a quartz The piezo electrical quartz crystal is deformed by the application of an electrical voltage. The crystal behaves like an electrical resonance circuit. Z: Quartz impedance with no load
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Philips Semiconductors, Costumer Support, 04/12/200316 Oscillation conditions The quartz is not perfect. It has losses Oscillations can not appear Losses must be compensated « Negative resistor » (amplifier) needed
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Philips Semiconductors, Costumer Support, 04/12/200317 Let’s see electrical characteristics of a crystal
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Philips Semiconductors, Costumer Support, 04/12/200318 Crystal has others defaults: Tolerance on components value Frequency initial adjustment: RefCal Done on the production line Frequency shift vs. temperature Temperature compensation Frequency shift with age Frequency adjustment: AFC
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Philips Semiconductors, Costumer Support, 04/12/200319 Crystal temperature deviation 416 Hz deviation 520 Hz deviation 156 Hz deviation
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Philips Semiconductors, Costumer Support, 04/12/200320 Influence of V supply (Pushing) Regulated supply Influence of load (Pulling) Load adjustment + Buffers + Frequency drift with time Frequency enslavement: AFC
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Philips Semiconductors, Costumer Support, 04/12/200321 Final overview of the clock AFC RefCal Output BB Output RF
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Philips Semiconductors, Costumer Support, 04/12/200322 Discrete vs integrated clock Two ways to implement the clock: Discrete. Each function is done with discrete components Module. Reference clock is generated by a component containing all functions
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Philips Semiconductors, Costumer Support, 04/12/200323 Module clock Advantages Nber of components Reduced bulkiness Nber of supply Nber of signals Easy to implement Disadvantages Cost (twice discrete’s) No possible adaptation
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Philips Semiconductors, Costumer Support, 04/12/200324 Discrete clock Disadvantages Nber of components Bulkiness Nber of supply Nber of signals difficult to implement Technical limits Advantages Cost (half module) Possible adaptation
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Philips Semiconductors, Costumer Support, 04/12/200325 Discrete clock is limited to GPRS class 10, 2 Tx slots (due to PA heat) Synchronisation algorithm is common Temperature compensation: hardware way for discrete Integrated in the module Temperature and load compensation are made internally for the module: RefCal not needed. Consumption is a little bit important for module (~ 1 mA).
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Philips Semiconductors, Costumer Support, 04/12/200326 Overview of a module clock No RefCal
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Philips Semiconductors, Costumer Support, 04/12/200327 Training Content: Reference clock presentation Reference clock contents Reference clock on Sysol ME Reference clock working on Sysol ME Reference clock performances to check Problems linked to reference clock Reference clock on Dragon Fly
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Philips Semiconductors, Costumer Support, 04/12/200328 REFERENCE CLOCK ON SYSOL ME
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Philips Semiconductors, Costumer Support, 04/12/200329 Topology of the 26MHz The topology of the 26MHz oscillator is from Pierce principle as follows. 3537
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Philips Semiconductors, Costumer Support, 04/12/200330 Characteristics of the ref. clock on SSME Frequency: 26 MHz Radio: UAA3537. Need 26 MHz BBand: OM6357-7 (50874-6): 26 MHz Quartz: NDK NX4025DA 26 MHz Semi-integrated clock: Three blocks are in 3537: - RF buffer - BB buffer - Negative resistance
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Philips Semiconductors, Costumer Support, 04/12/200331 Supply for the clock: not needed. Negative resistance and buffers supplies are provided by 3537 with an internal regulator. Signals: 2 signals are needed: AFC: provided by BB Clkfdbx: provided by 3537 RefCal signal is generated by a register of 3537. (CAFC register)
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Philips Semiconductors, Costumer Support, 04/12/200332 Crystal NX4025DA specifications
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Philips Semiconductors, Costumer Support, 04/12/200333 VariableL oading Quartz Temperature compensation RF Buffer BB Buffer Negative resistance Clkfdbk from 3537 AFC: from BB Internal regulator
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Philips Semiconductors, Costumer Support, 04/12/200334 Training Content: Reference clock presentation Reference clock contents Reference clock on Sysol ME Reference clock working on Sysol ME Reference clock performances to check Problems linked to reference clock Reference clock on Dragon Fly
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Philips Semiconductors, Costumer Support, 04/12/200335 REFERENCE CLOCK WORKING ON SYSOL ME
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Philips Semiconductors, Costumer Support, 04/12/200336 Some hard parameters Magnitude of the clock: Input of 3537: 670 mVpp Provided by 3537: 1.2 Vpp DC value: 1.2 V 3537 specifications.
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Philips Semiconductors, Costumer Support, 04/12/200337 Input of 3537 F=26 MHz (Refin pin) Output of 3537 F=26MHz
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Philips Semiconductors, Costumer Support, 04/12/200338 Synchronisation with network Step 1: wake up of the 26 MHz 26 MHz is not the real frequency. Clock is not enslaved Step 2: Mobiles goes in Rx mode to receive the FCB DESPITE the clock is not at 26 MHz (FCB: Frequency Control Burst) Step 3: with FCB, mobile can correct its frequency error.
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Philips Semiconductors, Costumer Support, 04/12/200339 After synchronisation with network Regularly, mobile measures the frequency error with FCB Frequency Offset Information (FOI) Software value, given by tracer or a communication tester (CMD) Coded with 16 bits (2 bytes). Positive FOI value = negative frequency error. Negative FOI value = positive frequency error. Using FOI information, mobile adjusts AFC.
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Philips Semiconductors, Costumer Support, 04/12/200340 Using FOI information, mobile increases or decreases AFC. Since AFC is provided by AuxDAC2 on 50732, it can change only step by step. Foi_step How mobile adjusts AFC: FOI_STEP
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Philips Semiconductors, Costumer Support, 04/12/200341 FOI_STEP Calculation Take the specified minimum voltage range of the AFC DAC defined by ΔV ( unit in V). The correction per LSB is derived by: ΔV/(2 n ) for a n bits DAC (unit in V). Then, the TCXO slope needs to be measured on a statistical quantity of units (> 30). The slope is expressed by S (unit in ppm/V).
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Philips Semiconductors, Costumer Support, 04/12/200342 FOI_STEP phy is equal to (ΔV x S x F)/ 2 n (unit in Hz/LSB) Where F is the middle Rx RF frequency corresponding to the band used for the calculation 881.4 x 10 6 Hz for the GSM850 (channel 189). 942.4 x 10 6 Hz for the GSM900 (channel 62). 1842.6 x 10 6 Hz for the GSM1800 (channel 699). 1960 x 10 6 Hz for the GSM1900 (channel 661). The correction is: (FOI/ FOI_STEP phy ) (unit in LSB)
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Philips Semiconductors, Costumer Support, 04/12/200343 BUT: a division between an integer and a real number is an inconvenient operation for soft Parameter FOI_step FOI_STEP = 2 16 /(FOI_STEP phy ) (unit LSB/Hz) Thus, we have: [2 16 /(FOI_STEP phy )] x [FOI / 2 16 ]=[FOI_STEP] x [FOI / 2 16 ] Instead of: FOI / FOI_STEP phy One multiplication better than a division One division with an integer One division between one integer and one real number
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Philips Semiconductors, Costumer Support, 04/12/200344 What will happen if initial frequency error is too important? Mobile can not synchronize Use of an Initial FOI (FOInit)
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Philips Semiconductors, Costumer Support, 04/12/200345 DSP has a Rx frequency window (+/- 25 kHz). It comes from DSP firmware. Mobile can synchronize only if frequency error is in this window FOI_Init put frequency error in the synchronization range
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Philips Semiconductors, Costumer Support, 04/12/200346 Settings of this parameters REF_Cal, FOI_Init, FOI_Step are stored in EEPROM It is possible to see and change their value with TAT software Ref_Cal and FOI_Init are tuned for each mobile. Ref_Cal is first tuned, then Foi_Init. FOI is a soft parameter. Value accessible only with TRACER or Communication TESTER
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Philips Semiconductors, Costumer Support, 04/12/200347 FoiStep: One per band RefCal Foi-Init: Needs an HWL reset (init button)
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Philips Semiconductors, Costumer Support, 04/12/200348 Values for Sysol ME (updated on W347) FOIinit: 2340 * RefCal: 78 ** FOIstep GSM850: 8082 FOIstep GSM900: 7759 FOIstep GSM1800: 3856 FOIstep GSM1900: 3634 * : Depends on layout, quartz, diode… ** : Statistical value * & **: Defaults values – Tuned in production
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Philips Semiconductors, Costumer Support, 04/12/200349 GSM standard requirements: In all bands, in normal conditions, frequency error must not be greater than 0.1 ppm For GSM 850: 85 Hz For GSM 900: 90 Hz For DCS 1800: 180 Hz For PCS 1900: 190 Hz
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Philips Semiconductors, Costumer Support, 04/12/200350 Training Content: Reference clock presentation Reference clock contents Reference clock on Sysol ME Reference clock working on Sysol ME Reference clock performances to check Problems linked to reference clock Reference clock on Dragon Fly
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Philips Semiconductors, Costumer Support, 04/12/200351 REFERENCE CLOCK PERFORMANCES TO CHECK
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Philips Semiconductors, Costumer Support, 04/12/200352 List of measurements to check 26 MHz Frequency drift vs output power Current freq error when Pout goes from PCL high to low and low to high Waveform Wake-up time DAC frequency correction AFC linearity Frequency drift with temperature Spectrum
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Philips Semiconductors, Costumer Support, 04/12/200353 Wake up time with temperature: Spec: 9 ms; meas: 1.09 ms Spectrum (Refin pin): spec: -20 dBc; meas: -37.6 dBc (H2) Frequency drift with temperature (–30 to 70°): Spec: +/- 7 ppm; Measured: +/- 2 ppm Waveform: Vpp = 1.25 V; Duty Cycle = 42 – 57 % Some specs and measurements:
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Philips Semiconductors, Costumer Support, 04/12/200354 Training Content: Reference clock presentation Reference clock contents Reference clock on Sysol ME Reference clock working on Sysol ME Reference clock performances to check Problems linked to reference clock Reference clock on Dragon Fly
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Philips Semiconductors, Costumer Support, 04/12/200355 PROBLEMS LINKED TO 26 MHz
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Philips Semiconductors, Costumer Support, 04/12/200356 Main problem: Frequency error 26 MHz: origin of all synthesized frequencies Frequency drift on 26 MHz means frequency drift on all synthesizers degradation of frequency error
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Philips Semiconductors, Costumer Support, 04/12/200357 Degradation also of other performances Phase error Training sequence loss Problem of synchronisation Sensitivity DUE TO FREQUENCY ERROR
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Philips Semiconductors, Costumer Support, 04/12/200358 Case of the sensitivity Sensitivity can be degraded by phase noise But also by the Ref Clock itself with the harmonics GSM 850: H34 for channel 202 GSM 900: H36 for channel 5 Concern mainly GSM 850 and GSM 900
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Philips Semiconductors, Costumer Support, 04/12/200359 Training Content: Reference clock presentation Reference clock contents Reference clock on Sysol ME Reference clock working on Sysol ME Reference clock performances to check Problems linked to reference clock Reference clock on Dragon Fly
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Philips Semiconductors, Costumer Support, 04/12/200360 REFERENCE CLOCK ON DRAGON FLY
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Philips Semiconductors, Costumer Support, 04/12/200361 Characteristics of the ref. clock on Dragon Fly Frequency: 26 MHz Radio: UAA3537. Need 26 MHz BBand: PCF 5213 (SWIFT) 26 MHz Internal divider in 3537 not used Integrated clock: Module END 3512A (NDK) Buffers for radio and BB still in 3537
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Philips Semiconductors, Costumer Support, 04/12/200362 Supply for the clock: 2.5 V, provided by an internal regulator in 3537 Signals: 1 signal is now needed: AFC: provided by BB Clkfdbx: no more used RefCal: not used Synchronization algorithm is identical
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Philips Semiconductors, Costumer Support, 04/12/200363 Temp. Comp: Unused Variable load: unused Supply: Internal regulator Buffers Module AFC
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Philips Semiconductors, Costumer Support, 04/12/200364 Values for Dragon Fly (updated on W347) FOIinit: 2230 – Default value for Vafc=1.2V RefCal: Unused FOIstep GSM850: 11669 FOIstep GSM900: 10922 FOIstep GSM1800: 5601 FOIstep GSM1900: 5243
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Philips Semiconductors, Costumer Support, 04/12/200365 Used module on Dragon Fly: END 3512A
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Philips Semiconductors, Costumer Support, 04/12/200366
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Philips Semiconductors, Costumer Support, 04/12/200367 Input of 3537 F=26 MHz (Refin pin) Output of 3537 F=26 MHz (Clockout pin)
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Philips Semiconductors, Costumer Support, 04/12/200368 CONCLUSION: COMPARISON WITH SYSOL 2
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Philips Semiconductors, Costumer Support, 04/12/200369 Since Sysol 2 clock is a module, it’s easier to compare with Dragon Fly. More integrated: On sysol 2: external and discrete buffer External supply by a regulator INTEGRATED IN SYSOL ME AND DRAGON FLY. Frequency change: 26 MHz instead of 13.
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Philips Semiconductors, Costumer Support, 04/12/200370 QUESTIONS
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