1 / 52

A System Level Design for a Bluetooth Front-end Receiver

AALBORG UNIVERSITY Department of Communication Technology. A System Level Design for a Bluetooth Front-end Receiver. Group #789. Angela Lin Shekar Nethi Shadi Tawfik. Supervisor. Jan H. Mikkelsen. January 9, 2004. Contents. Introduction to Bluetooth. Radio Receivers Architectures.

bibiane
Download Presentation

A System Level Design for a Bluetooth Front-end Receiver

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. AALBORG UNIVERSITY Department of Communication Technology A System Level Design for a Bluetooth Front-end Receiver Group #789 Angela Lin Shekar Nethi Shadi Tawfik Supervisor Jan H. Mikkelsen January 9, 2004

  2. Contents • Introduction to Bluetooth • Radio Receivers Architectures • Bluetooth Receiver Design • MATLAB Modeling • Conclusion & Future Work • Working Process 1/50

  3. Introduction to BluetoothDefinition Introduction to Bluetooth • Bluetooth is a wireless technology standard intended to be a cable replacement Radio Receivers Architectures • Main radio specifications: • Short range (10 - 100 m) Bluetooth Receiver Design • Unlicensed ISM band (2.4 - 2.4835 GHz) MATLAB Modeling • GFSK Modulation (BT = 0.5, h = 0.28 - 0.35) Conculsion & Future Work Working Process • Bit rate of 1Mbps • Frequency Hopping (1600 Hops/sec) 2/50

  4. Introduction to BluetoothBackground Introduction to Bluetooth • Bluetooth was first originated by Ericsson in 1994, with the main targets being low cost, low power and low form factor Radio Receivers Architectures • In 1998, the Bluetooth Special Interest Group (SIG) was formed Bluetooth Receiver Design • SIG’s initial target price of a Bluetooth solution $5 • Currently, average price is around $25 MATLAB Modeling • High cost is the main problem delaying the widespread of Bluetooth Conculsion & Future Work • Radio part accounts for 80% of the total cost Working Process 3/50

  5. Radio Receivers ArchitecturesIntroduction Introduction to Bluetooth • All wireless front-end receivers employ downconversion to an Intermediate Frequency (IF) Radio Receivers Architectures • Achieve higher Q components • Avoid high power consumption Bluetooth Receiver Design • Architectures can be classified according to IF used MATLAB Modeling • The Superheterodyne Receiver • I/Q Processing Receivers: Conculsion & Future Work -The Direct Conversion Receiver - The Low IF Receiver Working Process 4/50

  6. Radio Receivers ArchitecturesThe Superheterodyne Receiver – Operation (1) Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design • RF Band select filter MATLAB Modeling • reduces linearity requirements for later blocks • avoids desensitization ofthe receiver Conculsion & Future Work • Low Noise Amplifier (LNA) Working Process • Minimum noise added during amplification • Mixer • DownconvertsRF signal to IF (usually IF = RF/10) 5/50

  7. Radio Receivers ArchitecturesThe Superheterodyne Receiver – Operation (2) Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design • RF image-band-reject filter MATLAB Modeling Conculsion & Future Work Working Process • IF channel select filter • High Q filter for channel selection 6/50

  8. Radio Receivers ArchitecturesThe Superheterodyne Receiver – Trade-offs Introduction to Bluetooth • High IF Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Razavi-RF Microelectronics • Low IF Conculsion & Future Work Working Process Razavi-RF Microelectronics 7/50

  9. Radio Receivers ArchitecturesThe Superheterodyne Receiver – Pros & Cons Introduction to Bluetooth • Bulky external components • Pros • High sensitivity and selectivity  successive downconversion Radio Receivers Architectures BPF1 BPF2 BPF3 BPF4 Bluetooth Receiver Design VLO1 VLO2 MATLAB Modeling • Cons Conculsion & Future Work  Cannot be integrated Working Process  Expensive  High power consumption 8/50

  10. Complex Downconversion • LO signal contains positive OR negative tones • Image rejection after downconversion Big Advantage Introduction to BluetoothIQ Processing Receivers – Theory Introduction to Bluetooth • Traditional Downconversion • LO signal contains positive AND negative tones Radio Receivers Architectures • Image rejection before downconversion Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process 9/50

  11. Introduction to BluetoothIQ Processing Receivers – Physical Realization Introduction to Bluetooth I Radio Receivers Architectures Bluetooth Receiver Design Q MATLAB Modeling • Common disadvantage: IQ mismatches Conculsion & Future Work Working Process 1% gain and phase mismatch reduces IRR to 35dB 10/50

  12. Image rejection relaxed  small IQ mismatches can be tolerated Radio Receivers ArchitecturesDirect Conversion Receiver – Operation Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design • DCR can be fully integrated MATLAB Modeling Conculsion & Future Work Working Process 11/50

  13. Radio Receivers ArchitecturesDirect Conversion Receiver – Problems (1) Introduction to Bluetooth • DC offset • Imperfect isolation between different ports Radio Receivers Architectures • Distortion of downconverted signal Bluetooth Receiver Design • Static and dynamic DC offsets MATLAB Modeling Conculsion & Future Work Working Process 12/50

  14. Radio Receivers ArchitecturesDirect Conversion Receiver – Problems (2) Introduction to Bluetooth • Flicker noise  major noise contributor in MOS devices Radio Receivers Architectures • Even order non-linearities Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Razavi-RF Microelectronics Working Process • LO leakage  in-band interference for other receivers 13/50

  15. Radio Receivers ArchitecturesLow IF Receiver – Operation Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling • Image rejection  Polyphase filter Conculsion & Future Work Working Process 14/50

  16. Radio Receivers ArchitecturesLow IF Receiver – Pros & Cons Introduction to Bluetooth • IQ mismatches are a major concern • Pros • Integrability Radio Receivers Architectures • DC offsets, flicker noise and even order distortion can be easily removed Bluetooth Receiver Design Combined advantages of Superheterodyne and DCR • Cons MATLAB Modeling Conculsion & Future Work Working Process 15/50

  17. Radio Receivers ArchitecturesSummary Introduction to Bluetooth Radio Receivers Architectures Off-chip Components Bluetooth Receiver Design Full Integration MATLAB Modeling Conculsion & Future Work Full Integration Working Process A low IF architecture is found suitable for a Bluetooth receiver 16/50

  18. Bluetooth Receiver DesignStrategy Introduction to Bluetooth Radio Receivers Architectures Overall Receiver Parameters Calculation Bluetooth Receiver Design Verification MATLAB Modeling Block Level Design Conculsion & Future Work Working Process 17/50

  19. Bluetooth Receiver DesignOverall Parameters – Total Noise Figure Introduction to Bluetooth Radio Receivers Architectures • From Bluetooth radio specifications • Sensitivity (PMIN) = -70 dBm Bluetooth Receiver Design • Bandwidth (B) = 1 MHz • (BER)MAX = 10-3  Mapping for GFSK  (SNRo)MAX = 21 dB  But, Carrier-to-Co-Channel interferenece (C/ICO-CH) = 11 dB MATLAB Modeling Conculsion & Future Work (SNRo)MAX = 11 dB Working Process NFTOT≤33 dB 18/50

  20. Bluetooth Receiver DesignOverall Parameters – Linearity Introduction to Bluetooth Radio Receivers Architectures • IM test requirements • Desired signal (C) = -70 dBm Bluetooth Receiver Design • Two interferers  sine signal, PINT1 = -39 dBm GFSK modulated signal, PINT2 = -39 dBm MATLAB Modeling PINT= -39 dBm Conculsion & Future Work • Carrier-to-Co-Channel interferenece (C/ICO-CH) = 11 dB Working Process IP3i,TOT≥ – 21dBm 19/50

  21. Bluetooth Receiver DesignOverall Parameters – SFDR Introduction to Bluetooth • Sensitivity level (PMIN) = -70 dBm Radio Receivers Architectures • Maximum interference power level (PINT,MAX)  Follows from definition of SFDR  Total noise figure (FTOT) = 32 dB  Total 3rd order Intercept Point (IP3iTOT) = -20 dBm Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process PINT,MAX = -40.6 dBm SFDR = 29.3 dB 20/50

  22. Bluetooth Receiver DesignOverall Parameters – AGC Range Introduction to Bluetooth Radio Receivers Architectures • Sensitivity level (PMIN) = -70 dBm • Maximum signal level (PMAX) = -20 dBm Bluetooth Receiver Design • ADC full scale power (PFS,ADC)  ADC Full scale voltage (VFS,ADC) = 0.8 V  ADC Input resistance (Rin,ADC) = 6 kW MATLAB Modeling Conculsion & Future Work Working Process PFS,ADC = -12.73 dBm GTOT,MAX = 57.27 dB GTOT,MIN= 7.27 dB 21/50

  23. Bluetooth Receiver DesignOverall Parameters – In-band Filtering Requirements Introduction to Bluetooth • In-band blockers test specifies a desired signal power level of - 60 dBm Radio Receivers Architectures Overall filtering requirements for in-band interferers In-band interferers power levels Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process 22/50

  24. Bluetooth Receiver DesignOverall Parameters – Out-of-band Filtering Requirements Introduction to Bluetooth • Out-of-band blockers test specifies a desired signal power level of - 67 dBm Radio Receivers Architectures Overall filtering requirements for out-of-band interferers Out-of-band interferers power levels Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process 23/50

  25. Rx’ Bluetooth Receiver DesignOverall Parameters – Desensitization & Blocking (1) Introduction to Bluetooth • Main Assumption • Overall gain reduction is due to gain reduction in LNA only Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process 24/50

  26. DNF from test with minimum desired signal power (PSIGNAL) • In-band blockers test: PSIGNAL = - 60 dBm • Out-of-band blockers test: PSIGNAL = - 67 dBm • IM test: PSIGNAL = - 64 dBm Bluetooth Receiver DesignOverall Parameters – Desensitization & Blocking (2) Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design • Typical values for CMOS LNAs • GLNA = 15 dB MATLAB Modeling • NFLNA = 4 dB Conculsion & Future Work Working Process DNF = 3 dB G’LNA ≥ 15.5 dB 25/50

  27. Bluetooth Receiver DesignOverall Parameters – Desensitization & Blocking (3) Introduction to Bluetooth Radio Receivers Architectures • To obtain a3 Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work • Using a typical value for a CMOS LNA  IP3i,LNA = - 9 dBm Working Process • Referring to a 50 W load a3 = 0.6 mV-2 | B | ≤ 1.37 mV 26/50

  28. Bluetooth Receiver DesignOverall Parameters – Desensitization & Blocking (4) Introduction to Bluetooth BMAX =±1.37 mV Radio Receivers Architectures • Referring to a 50 W load Bluetooth Receiver Design PBL,MAX = – 17.3 dBm MATLAB Modeling • 8 dB attenuation required before LNA Conculsion & Future Work Working Process Bluetooth specifications v1.1 27/50

  29. Bluetooth Receiver DesignBlock Level Design – Assumptions Introduction to Bluetooth • Assumptions for unavailable values Radio Receivers Architectures • RF band select filter is almost perfectly linear IP3i,RF = 30 dBm • RF band select filter attenuation for f = 6 GHz continues constantly for higher frequencies Bluetooth Receiver Design • Polyphase channel select filter for adjacent channels (Df ≥ 3 MHz) extracted from a LPF of the same order MATLAB Modeling Conculsion & Future Work Working Process 28/50

  30. Bluetooth Receiver DesignBlock Level Design – Parameters Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process 29/50

  31. Bluetooth Receiver DesignSummary and Conclusion Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process A low cost Bluetooth low IF receiver can be implemented in a standard CMOS process 30/50

  32. MATLAB ModelingAim and Accomplishments Introduction to Bluetooth • Previous calculations use approximate formulas Radio Receivers Architectures • Building the front-end receiver in a simulation environment is a further step towards more accurate evaluation of performance Bluetooth Receiver Design • The group was able to build behavioral models in MATLAB for the following: MATLAB Modeling • RF noise Conculsion & Future Work • RF band select filter • LNA (Mixer) Working Process • Polyphase filter 31/50

  33. MATLAB ModelingRF Simulation Problem Introduction to Bluetooth • A computer can only deal with discrete time signals • Sampling of input band-pass signal is required Radio Receivers Architectures • Still bounded with Nyquist Sampling Theorem fs ≥ 2fmax Bluetooth Receiver Design • For RF signals, sampling frequency would be very high MATLAB Modeling • Huge number of samples • Computationally inefficient Conculsion & Future Work • Therefore, use base-band representation of band-pass signals Working Process • Model built to deal with base-band form input • Model gives output in base-band form 32/50

  34. is the complex envelope  • contains all transmitted information • is a base-band signal MATLAB ModelingBase-Band Representation of Band-Pass Signals Introduction to Bluetooth • Any band-pass (modulated) signal can be written as Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling • Consequently, the band-pass signal can be written as Conculsion & Future Work Working Process • I(t) and Q(t) are real signals • Canonical forms of transmitters and receivers 33/50

  35. m(t) MATLAB ModelingGFSK Signal Generation – Basic Principle Introduction to Bluetooth g(t ) Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process 34/50

  36. MATLAB ModelingGFSK Signal Generation - Waveforms Gaussian shaped bits Bipolar bits stream Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling PSD of GFSK signal Conculsion & Future Work • BT = 0.5 Working Process • modulation index = 0.35 35/50

  37. MATLAB ModelingRF Noise Model – Basic Principle Introduction to Bluetooth • The PSD of white noise is infinite • Direct simulation of white noise is impossible Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling • Usually, we have a limited bandwidth of interest Conculsion & Future Work Working Process 36/50

  38. MATLAB ModelingRF Noise Model – Algorithm Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process 37/50

  39. MATLAB ModelingRF Noise Model – Results Introduction to Bluetooth PSD of generated RF noise • Simulation parameters Radio Receivers Architectures • Two sided PSD ≡ NF = 3dB Bluetooth Receiver Design • Center frequency = 200 MHz • Noise bandwidth = 100 MHz MATLAB Modeling • Sampling frequency = 1 GHz • Brick wall filter ≈ 8th order Butterworth LPF Conculsion & Future Work Working Process 38/50

  40. MATLAB ModelingRF Filter Model – Basic Principle (1) Introduction to Bluetooth • General transfer function of any analog filter Radio Receivers Architectures Bluetooth Receiver Design • Using partial fractions expansion: MATLAB Modeling Conculsion & Future Work Working Process 39/50

  41. MATLAB ModelingRF Filter Model – Basic Principle (2) Introduction to Bluetooth • Output of RF band-pass filter Radio Receivers Architectures Bluetooth Receiver Design • For the RF band-pass signal • Carrier frequency >> bandwidth MATLAB Modeling • Spectrum ≈ zero outside bandwidth Conculsion & Future Work Working Process 40/50

  42. MATLAB ModelingRF Filter Model – Basic Principle (3) Introduction to Bluetooth From previous analysis we can now write Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process 41/50

  43. MATLAB ModelingRF Filter Model – Results Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work • Direct Implementation • Low-pass equivalent • First order bandpass filter • First order Butterworth LPF Working Process • Center frequency = 200 MHz • Bandwidth = 5 MHz • Bandwidth = 10 MHz • Sampling frequency = 1 GHz • Sampling frequency = 1 GHz 42/50

  44. MATLAB ModelingLNA Model – Basic Principle Introduction to Bluetooth • Model non-linearity  power series expansion Radio Receivers Architectures Bluetooth Receiver Design • Considering only fundamental component at the output MATLAB Modeling Conculsion & Future Work Working Process 43/50

  45. MATLAB ModelingLNA Model – Sine Wave Test Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work • Perfectly linear LNA • Non-linear LNA • Voltage gain (a1) = 15 dBV • Voltage gain (a1) = 15 dBV Working Process • a0 = a2 = a3= 0 • a0 , a2 , a3≠ 0 • Test signal: sine wave • Test signal: sine wave • Amplitude = 1 V • Amplitude = 1 V • Frequency = 5 Hz • Frequency = 5 Hz 44/50

  46. MATLAB ModelingLNA Model – GFSK Signal Test Introduction to Bluetooth • Perfectly linear LNA Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling • Non-linear LNA Conculsion & Future Work Working Process 45/50

  47. MATLAB ModelingPolyphase Filter Model – Basic Principle Introduction to Bluetooth • Polyphase filter deals with downconverted signal  direct simulation • Basic Transformation Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process 46/50

  48. MATLAB ModelingPolyphase Filter Model – Results Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work • Test signal: GFSK • Polyphase filter • Center frequency = 2 MHz • Center frequency = 2 MHz Working Process • Bandwidth = 1 MHz • Bandwidth = 1 MHz • Sampling frequency = 10 MHz 47/50

  49. Conclusion and Future Work Introduction to Bluetooth • Conclusions: • A low IF receiver architecture is suitable for Bluetooth Radio Receivers Architectures • The architecture can be implemented in a low cost standard CMOS process Bluetooth Receiver Design • Behavioral models for RF blocks can be implemented in MATLAB MATLAB Modeling Conculsion & Future Work • Future work: • Building a complete low IF receiver in MATLAB to perform more accurate tests Working Process 48/50

  50. Working ProcessTime Line Introduction to Bluetooth Radio Receivers Architectures Bluetooth Receiver Design MATLAB Modeling Conculsion & Future Work Working Process 49/50

More Related