Transcript Bluetooth Front

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
 Bluetooth Receiver Design
 MATLAB Modeling
 Conclusion & Future Work
 Working Process
1/50
Introduction to Bluetooth
Definition
Introduction
to Bluetooth
Radio
Receivers
Architectures
 Bluetooth is a wireless technology standard intended to be a cable
replacement
 Main radio specifications:
Bluetooth
Receiver
Design
 Short range
(10 - 100 m)
MATLAB
Modeling
 Unlicensed ISM band
(2.4 - 2.4835 GHz)
Conculsion &
Future Work
 GFSK Modulation
(BT = 0.5, h = 0.28 - 0.35)
Working
Process
 Bit rate of 1Mbps
 Frequency Hopping
(1600 Hops/sec)
2/50
Introduction to Bluetooth
Background
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
 Bluetooth was first originated by Ericsson in 1994, with the main
targets being low cost, low power and low form factor
 In 1998, the Bluetooth Special Interest Group (SIG) was formed
 SIG’s initial target price of a Bluetooth solution $5
MATLAB
Modeling
 Currently, average price is around $25
Conculsion &
Future Work
 High cost is the main problem delaying the widespread of Bluetooth
Working
Process
 Radio part accounts for 80% of the total cost
3/50
Radio Receivers Architectures
Introduction
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 All wireless front-end receivers employ downconversion to an
Intermediate Frequency (IF)
 Achieve higher Q components
 Avoid high power consumption
 Architectures can be classified according to IF used
 The Superheterodyne Receiver

I/Q Processing Receivers:
- The Direct Conversion Receiver
- The Low IF Receiver
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Radio Receivers Architectures
The Superheterodyne Receiver – Operation (1)
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 RF Band select filter
 reduces linearity requirements for later blocks
 avoids desensitization of the receiver
 Low Noise Amplifier (LNA)
 Minimum noise added during amplification
 Mixer
 Downconverts RF signal to IF (usually IF = RF/10)
5/50
Radio Receivers Architectures
The Superheterodyne Receiver – Operation (2)
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
 RF image-band-reject filter
Conculsion &
Future Work
Working
Process
 IF channel select filter
 High Q filter for channel selection
6/50
Radio Receivers Architectures
The 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
Radio Receivers Architectures
The Superheterodyne Receiver – Pros & Cons
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
 Pros
 High sensitivity and selectivity  successive downconversion
BPF1
BPF2
BPF3
VLO1
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
BPF4
VLO2
 Cons
 Bulky external components
 Cannot be integrated
 Expensive
 High power consumption
8/50
Introduction to Bluetooth
IQ Processing Receivers – Theory
Introduction
to Bluetooth
 Traditional Downconversion
Radio
Receivers
Architectures
 LO signal contains
positive AND negative
tones
Bluetooth
Receiver
Design
 Image rejection before
downconversion
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 Complex Downconversion
 LO signal contains
positive OR negative tones
 Image rejection after
downconversion
Big Advantage
9/50
Introduction to Bluetooth
IQ Processing Receivers – Physical Realization
Introduction
to Bluetooth
I
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Q
 Common disadvantage: IQ mismatches
Conculsion &
Future Work
Working
Process
1% gain and phase mismatch reduces IRR to 35dB
10/50
Radio Receivers Architectures
Direct Conversion Receiver – Operation
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
 DCR can be fully integrated
 Image rejection relaxed  small IQ mismatches can be tolerated
Working
Process
11/50
Radio Receivers Architectures
Direct Conversion Receiver – Problems (1)
Introduction
to Bluetooth
 DC offset
Radio
Receivers
Architectures
 Imperfect isolation between different ports
Bluetooth
Receiver
Design
 Static and dynamic DC offsets
 Distortion of downconverted signal
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
12/50
Radio Receivers Architectures
Direct Conversion Receiver – Problems (2)
Introduction
to Bluetooth
Radio
Receivers
Architectures
 Flicker noise  major noise contributor in MOS devices
 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
Radio Receivers Architectures
Low 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
Radio Receivers Architectures
Low IF Receiver – Pros & Cons
Introduction
to Bluetooth
Radio
Receivers
Architectures
 Pros
 Integrability
 DC offsets, flicker noise and even order distortion can be easily
removed
Bluetooth
Receiver
Design
MATLAB
Modeling
Combined advantages of Superheterodyne and DCR
 Cons
 IQ mismatches are a major concern
Conculsion &
Future Work
Working
Process
15/50
Radio Receivers Architectures
Summary
Introduction
to Bluetooth
Radio
Receivers
Architectures
Power
Consumption
Form
Factor
High
High
High
High
Off-chip Components
Low
Direct
Conversion
Conculsion &
Future Work
Working
Process
Cost
Superheterodyne
Bluetooth
Receiver
Design
MATLAB
Modeling
Performance
 DC offset
 Flicker noise
 Even order distortion
 LO leakage
Low
Low IF
Low
 IQ mismatches
Low
Low
Full Integration
Low
Low
Low
Full Integration
A low IF architecture is found suitable for a Bluetooth receiver
16/50
Bluetooth Receiver Design
Strategy
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
Bluetooth Receiver Design
Overall Parameters – Total Noise Figure
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
 From Bluetooth radio specifications
 Sensitivity (PMIN) = -70 dBm
 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
(SNRo)MAX = 11 dB
Working
Process
NFTOT ≤ 33 dB
18/50
Bluetooth Receiver Design
Overall Parameters – Linearity
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
 IM test requirements
 Desired signal (C) = -70 dBm
 Two interferers
 sine signal, PINT1 = -39 dBm
 GFSK modulated signal, PINT2 = -39 dBm
PINT = -39 dBm
Conculsion &
Future Work
Working
Process
 Carrier-to-Co-Channel interferenece (C/ICO-CH) = 11 dB
IP3i,TOT ≥ – 21dBm
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Bluetooth Receiver Design
Overall Parameters – SFDR
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
 Sensitivity level (PMIN) = -70 dBm
 Maximum interference power level (PINT,MAX)
 Follows from definition of SFDR
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 Total noise figure (FTOT) = 32 dB
 Total 3rd order Intercept Point (IP3iTOT) = -20 dBm
PINT,MAX = -40.6 dBm
SFDR = 29.3 dB
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Bluetooth Receiver Design
Overall Parameters – AGC Range
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
 Sensitivity level (PMIN) = -70 dBm
 Maximum signal level (PMAX) = -20 dBm
 ADC full scale power (PFS,ADC)
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 ADC Full scale voltage (VFS,ADC) = 0.8 V
 ADC Input resistance (Rin,ADC) = 6 kW
PFS,ADC = -12.73 dBm
GTOT,MAX = 57.27 dB
GTOT,MIN = 7.27 dB
21/50
Bluetooth Receiver Design
Overall Parameters – In-band Filtering Requirements
Introduction
to Bluetooth
Radio
Receivers
Architectures
 In-band blockers test specifies a desired signal power level
of - 60 dBm
In-band interferers
power levels
Overall filtering requirements
for in-band interferers
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
22/50
Bluetooth Receiver Design
Overall Parameters – Out-of-band Filtering Requirements
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
 Out-of-band blockers test specifies a desired signal power level
of - 67 dBm
Out-of-band interferers
power levels
Overall filtering requirements
for out-of-band interferers
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
23/50
Bluetooth Receiver Design
Overall Parameters – Desensitization & Blocking (1)
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
 Main Assumption
 Overall gain reduction is due to gain reduction in LNA only
FTOT = FLNA+
FRx’ – 1
GLNA
MATLAB
Modeling
Conculsion &
Future Work
Rx’
Working
Process
24/50
Bluetooth Receiver Design
Overall Parameters – Desensitization & Blocking (2)
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 Typical values for CMOS LNAs
 GLNA = 15 dB
 NFLNA = 4 dB
 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
DNF = 3 dB
G’LNA ≥ 15.5 dB
25/50
Bluetooth Receiver Design
Overall Parameters – Desensitization & Blocking (3)
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design

 To obtain a3
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 Using a typical value for a CMOS LNA  IP3i,LNA = - 9 dBm
 Referring to a 50 W load
a3 = 0.6 mV-2
| B | ≤ 1.37 mV
26/50
Bluetooth Receiver Design
Overall Parameters – Desensitization & Blocking (4)
BMAX = ±1.37 mV
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
 Referring to a 50 W load
PBL,MAX = – 17.3 dBm
MATLAB
Modeling
Conculsion &
Future Work
 8 dB attenuation
required before LNA
Working
Process
Bluetooth specifications v1.1
27/50
Bluetooth Receiver Design
Block Level Design – Assumptions
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
 Assumptions for unavailable values
 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
 Polyphase channel select filter for adjacent channels (Df ≥ 3 MHz)
extracted from a LPF of the same order
Conculsion &
Future Work
Working
Process
28/50
Bluetooth Receiver Design
Block Level Design – Parameters
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
29/50
Bluetooth Receiver Design
Summary 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
MATLAB Modeling
Aim and Accomplishments
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 Previous calculations use approximate formulas
 Building the front-end receiver in a simulation environment is a
further step towards more accurate evaluation of performance
 The group was able to build behavioral models in MATLAB for
the following:
 RF noise
 RF band select filter
 LNA (Mixer)
 Polyphase filter
31/50
MATLAB Modeling
RF Simulation Problem
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 A computer can only deal with discrete time signals
 Sampling of input band-pass signal is required
 Still bounded with Nyquist Sampling Theorem
fs ≥ 2fmax
 For RF signals, sampling frequency would be very high
 Huge number of samples
 Computationally inefficient
 Therefore, use base-band representation of band-pass signals
 Model built to deal with base-band form input
 Model gives output in base-band form
32/50
MATLAB Modeling
Base-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
Conculsion &
Future Work

is the complex envelope 

contains all transmitted information

is a base-band signal
 Consequently, the band-pass signal can be written as
Working
Process
 I(t) and Q(t) are real signals
 Canonical forms of transmitters and receivers
33/50
MATLAB Modeling
GFSK Signal Generation – Basic Principle
Introduction
to Bluetooth
Radio
Receivers
Architectures
g(t )
m(t)
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
34/50
MATLAB Modeling
GFSK Signal Generation - Waveforms
Introduction
to Bluetooth
Gaussian shaped bits
Bipolar bits stream
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
PSD of GFSK signal
Conculsion &
Future Work
Working
Process
 BT = 0.5
 modulation index = 0.35
35/50
MATLAB Modeling
RF Noise Model – Basic Principle
Introduction
to Bluetooth
Radio
Receivers
Architectures
 The PSD of white noise is infinite
 Direct simulation of white noise is impossible
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
 Usually, we have a limited bandwidth of interest
Working
Process
36/50
MATLAB Modeling
RF Noise Model – Algorithm
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
37/50
MATLAB Modeling
RF Noise Model – Results
Introduction
to Bluetooth
 Simulation parameters
Radio
Receivers
Architectures
 Two sided PSD ≡ NF = 3dB
Bluetooth
Receiver
Design
 Center frequency = 200 MHz
PSD of generated RF
noise
N ' / 2  k ( F 1)To / 2
 Noise bandwidth = 100 MHz
MATLAB
Modeling
 Sampling frequency = 1 GHz
Conculsion &
Future Work
 Brick wall filter ≈ 8th order
Butterworth LPF
Working
Process
38/50
MATLAB Modeling
RF 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
MATLAB Modeling
RF Filter Model – Basic Principle (2)
Introduction
to Bluetooth
 Output of RF band-pass filter
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
 For the RF band-pass signal
 Carrier frequency >> bandwidth
 Spectrum ≈ zero outside bandwidth
Conculsion &
Future Work
Working
Process
40/50
MATLAB Modeling
RF 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
MATLAB Modeling
RF Filter Model – Results
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 Direct Implementation
 Low-pass equivalent
 First order bandpass filter
 First order Butterworth LPF
 Center frequency = 200 MHz
 Bandwidth = 5 MHz
 Bandwidth = 10 MHz
 Sampling frequency = 1 GHz
 Sampling frequency = 1 GHz
42/50
MATLAB Modeling
LNA Model – Basic Principle
Introduction
to Bluetooth
 Model non-linearity  power series expansion
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
 Considering only fundamental component at the output
Conculsion &
Future Work
Working
Process
43/50
MATLAB Modeling
LNA Model – Sine Wave Test
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 Perfectly linear LNA
 Non-linear LNA
 Voltage gain (a1) = 15 dBV
 Voltage gain (a1) = 15 dBV
 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
MATLAB Modeling
LNA Model – GFSK Signal Test
Introduction
to Bluetooth
 Perfectly linear LNA
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
 Non-linear LNA
Working
Process
45/50
MATLAB Modeling
Polyphase Filter Model – Basic Principle
Introduction
to Bluetooth
 Polyphase filter deals with downconverted signal  direct simulation
Radio
Receivers
Architectures
 Basic Transformation
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
46/50
MATLAB Modeling
Polyphase Filter Model – Results
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 Polyphase filter
 Test signal: GFSK
 Center frequency = 2 MHz
 Center frequency = 2 MHz
 Bandwidth = 1 MHz
 Bandwidth = 1 MHz
 Sampling frequency = 10 MHz
47/50
Conclusion and Future Work
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 Conclusions:
 A low IF receiver architecture is suitable for Bluetooth
 The architecture can be implemented in a low cost standard
CMOS process
 Behavioral models for RF blocks can be implemented in
MATLAB
 Future work:
 Building a complete low IF receiver in MATLAB to perform
more accurate tests
48/50
Working Process
Time Line
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
49/50
Working Process
Analysis
Introduction
to Bluetooth
Radio
Receivers
Architectures
Bluetooth
Receiver
Design
 Problems arise from different expectations
 Expectations about working hours
 Supervisor guidance
 Working style
 RF design field
MATLAB
Modeling
Conculsion &
Future Work
Working
Process
 Key points to a good project
 Discussions
 Being good listeners
 Try to learn from each other
 Be self motivated
50/50
THANK YOU 