Using LMX3162 2.4-GHz Band TABLE CONTENTS ABSTRACT INTRODUCTION S

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Using LMX3162 2.4-GHz Band TABLE CONTENTS ABSTRACT INTRODUCTION S

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Using LMX3162 2.4-GHz Band
Using LMX3162 2.4-GHz Band
TABLE CONTENTS ABSTRACT INTRODUCTION STANDARDS TRANSCEIVER DESIGN SYNTHESIZER 4.1.1 Lock Time TRANSMITTER RECEIVER 4.3.1 Demodulation Parallel Tank 4.3.2 Performance CONCLUSION LIST FIGURES FIGURE Transceiver Blocks FIGURE Timing Open Loop Operation FIGURE Ultra Drift FIGURE Lock Time FIGURE Open Loop Frequency Drift 85°C FIGURE Bluetooth Modulated Signals FIGURE Block. Block FIGURE Harmonics Transmitter Output FIGURE Phase Noise Local Oscillator FIGURE LNA/PA Low-Power Mode FIGURE Receiver Chain Analysis FIGURE Quadrature Demodulation FIGURE Parallel Quadrature Tank FIGURE Diagram, 1e-3, FIGURE Diagram, FIGURE Diagram Bluetooth Test FIGURE Diagram Bluetooth 1-MHz Test FIGURE Diagram Bluetooth 2-MHz Test. (-81 dBm) FIGURE Diagram Bluetooth 3-MHz Test. (-72 dBm) FIGURE Bluetooth Intermodulation Test FIGURE Optional LNA/PA Bluetooth HomeRF/Upbanded DECT FIGURE Optimized Schematics LMX3162 Evaluation Board (include buffer) LIST TABLES TABLE Parameter Comparison 2.4-GHz Applications TABLE Interference Test Bluetooth TABLE Bill Materials LMX3162
National Semiconductor AN-1162 Wireless Communication January 2000
ABSTRACT monolithic radio transceiver will demonstrated emerging wireless data voice applications unlicensed 2.4-GHz band including Bluetooth, HomeRF Upbanded DECT standards. architecture functionality LMX3162 will described thoroughly. circuit blocks topology will discussed implement complete radio with measuring performance. These results illustrate single-chip LMX3162 possible solution support various standards band. INTRODUCTION Higher higher levels integration circuits have become trend over past decade. example, complete receiver chip been available industries many years ago. LMX3162 integrated circuit (IC) takes radio integration step further including receiver, transmitter, phase locked loop (PLL) same piece silicon. accordance with 1.3-GHz PLL, frequency doubler employed both receiver transmitter share same PLL. This reduces complexity system well avoiding problem injection locking pulling VCO. Figure shows typical implementation 2.4-GHz radio front-end transceiver. addition frequency doubler, 2.5-GHz low-noise mixer, intermediate-frequency (IF) amplifier, limiting amplifier, frequency discriminator, receivedsignal-strength indicator (RSSI) receiver, well buffer amplifier transmitter integrated LMX3162[1][2]. Only channel selection filters, loop filters required external components1. discrete noise amplifier (LNA) power amplifier (PA) optional depending system requirements various standards applications. standards have been developed exploding Home handheld service access information appliance market. this reason, unlicensed 2.4-GHz Industrial, Scientific Medical (ISM) band been received great amount interest wireless communications industry worldwide. common frequency range (2.4 2.483 GHz) Europe, Japan also made this band attractive many product manufacturers. Several companies have their solutions available market today. open standards will guarantee inter-operability between products different brands well gain customer acceptance market penetration. Recently, there been much activity developing products based Bluetooth HomeRF protocols.[3][4] regulator biasing capacitors included here.
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MICROWIREis trademark National Semiconductor Corporation.
2000 National Semiconductor Corporation
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FIGURE Transceiver Blocks STANDARDS Bluetooth2 standard radio-based wireless ports with 10-100 range wireless pico-LAN. comparison, Shared Wireless Access Protocol-Cordless Access SWAP-CA focused home networking with range. Another option moving Digital Enhanced Cordless Telephone (DECT) 2.4-GHz band since both Bluetooth HomeRF loosely based DECT. these standards specifically designed with frequency hopping algorithms work well presence microwave ovens also include page mode maximize battery life. overview different standards shown Table Bluetooth frequency range only. Bluetooth HomeRF performance requirements less stringent DECT standards. examples, sensitivity in-band blocking levels much relaxed. particular, HomeRF does need adjacent channel specification only requires co-channel interference third channel below signal. Moreover,
termodulation product (IIP3) requires only -39.5 dBm. Given these relaxed standards, optional device Bluetooth HomeRF. Without LNA, LMX3162 achieve sensitivity dBm. This further reduces number external components power consumption. power amplifier also optional because classes transmitting power defined both Bluetooth HomeRF. Deploying Bluetooth HomeRF accordance with DECT standard, difference between masks transmit spectrum, part 15[5], should noticed. DECT, down 1-MHz offset from desired channel, where data rate 1.152 Mbits/s GFSK product equals 0.5. There ways resolve this issue. minimal impact, simply lowering rate Mbits/s while keeping same product will decrease bandwidth transmit spectrum meet requirements. full DECT data rate, alternative method reduce product 0.35 that spectrum met. However, intersymbol interference (ISI) will degraded several
TABLE Parameter Comparison 2.4-GHz Applications Parameters FREQUENCY Band Channel Spacing Accuracy Lock Time (est) Drift MODULATION Type Deviation Burst Rate
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Bluetooth 2.402 GHz-2.480 1.000
HomeRF 2.404 GHz-2.478 1.000
Upbanded DECT 2.40 GHz-2.483 1.000
2-FSK (4-FSK)
(416.67 Blind Slot)
kHz/5 Slots
GFSK
kHz/ms
GFSK
Mbits/s
177.5
Mbit/s
Mbit/s
nom) 1.152 Mbits/s (1.0 Mbits/s)
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TABLE Parameter Comparison 2.4-GHz Applications (Continued) Parameters MODULATION Accuracy CONNECTION Duplex Access Voice Coder Data Rate Packet (TDMA) CVSD/PCM kb/s) kb/s Half Duplex 57.6 kb/s (return) 11.25 (100 dBc/Hz -101 dBc/Hz -111 dBc/Hz Packet (TDMA) ADPCM kb/s) kb/s 1600 kb/s TDMA ADPCM kb/s) kb/s (479 kb/s) Half Duplex dBc/Hz 1.728 -120 dBc/Hz 3.456 -134 dBc/Hz 5.128 +/-20 +/-50 Bluetooth HomeRF Upbanded DECT
Maximum Dwell Time TRANSMITTER Transmit Power Transmit Adjacent Channel Power
dBc/Hz dBc/Hz -102 dBc/Hz
Local Oscillator Phase Noise Offset Frequency RECEIVER Sensitivity (BER=1e-3) IIP3 Co-channel Interferer Input Level Adjacent Channel Interferers (C/1)
-39.5
TRANSCEIVER DESIGN
Synthesizer LMX3162 contains running half band utilizes frequency doubler synthesize desired frequencies shown Figure This architecture alleviates disturbance local oscillator (LO) when power amplifier (PA) switched radiation isolated "offsetting output frequency from frequency. HomeRF, Bluetooth Upbanded DECT half-duplex TDMA systems. data transmitted received different time slots. Therefore, shared between transmit receive sections. Simpler circuitry also means less power consumption. 4.1.1 Lock Time function desired carrier frequency before data transmission reception. time taken settle down within acceptable error called lock time. From Table obviously that lock time requirement from HomeRF. comparison, Bluetooth 416.67 Upbanded DECT with blind slot3 much relaxed.
blind slot operation allows certain latency provides enough time acquire lock. Before solving lock time problem, another issue should discussed. improve performance well reduce cost implementation, transceiver transmits receives data open loop mode[6]. first locked MICROWIREprogramming desired carrier frequency then shut down during data transmission reception. Figure illustrates timing diagram. this short duration, subsequently modulated baseband signal transmit mode idling receive mode. This implies drifting must negligible compared carrier frequency. order achieve frequency drift kHz/25 ms), large capacitor4 mandated. This modification limits loop bandwidth increases lock time substantially. (For complete MICROWIRE programming description, LMX3162 data sheet evaluation notes.[1][2].) loop capacitors discharge charge because leakage currents associated with charge pump varactor VCO.
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FIGURE Timing Open Loop Operation
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FIGURE Ultra Drift resolve this issue particular HomerRF), unity gain op-amp, CMOS sampling switch low-leakage capacitor employed between loop filter control line VCO, illustrated Figure This configuration handles lock time current leakage requirements using different values capacitors. With this implementation, small capacitor loop filter used provide loop bandwidth phase margin achieve required lock time while large capacitor (CS) control line reduces frequency drift. unity gain op-amp duplicates information (voltage) stored low-leakage capacitor (large capacitor) while lock. open loop mode, CMOS sampling switch used suspend operation op-amp with sufficient isolation these capacitors. Once closed, switch resumes sampling operation. choice this capacitor depends dielectric radiation properties material. Polypropylene even better capacitor advisable.
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gain (KVCO) MHz/V referred GHz. phase detector comparison frequency kHz5. second order loop filter designed with loop bandwidth phase margin 50°. Figure shows component values filter. lock time measured from falling edge signal that shuts down (PLL_PD) 1225 (2450 Output) within output). lock time shown Figure This less than HomeRF required. Given 1-MHz channel spacing 110.5 MHz, largest comparison frequency 0.25 because frequency doubler. frequency drift current leakage measured starting from rising edge PLL_PD. Figure demonstrates frequency drift 85°C. very drift Hz/ms much less than required HomeRF. There frequency jumps. first phase
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noise appears jump finite response time domain modulation analyzer. second jump common mode operating range op-amp. Since large gain, frequency jumps tens kilohertz even though only hundred fluctuates. Placing 10-M resistor parallel with loop filter will sink away bias current op-amp prevent saturation. occurrence second jump depends selection op-amp CMOS switch. current design, second jump occurs only after loop open long time. ms). case HomeRF, loop will idle open such long period.
Table shows that maximum dwell time 11.25 Bluetooth HomeRF. However, transceiver operating scan mode. (receiving only) Frequency drift avoided without additional circuitry closing receiving data. This result degradation error rate (BER) decibel(s), which acceptable since LMX3162 gives enough design margins sensitivity.
Transmitter LMX3162, direct modulation scheme employed shown Figure 7(a). simple cost solution comparison other options, such direct modulation close loop modulation. this section, LMX3162 will demonstrated transmit data with open loop modulation 2.4-GHz band. transmit signal, shaped baseband signal applied tuning pin7 assure bandwidth efficient. amplitude signal from baseband processor needs adjusted obtain frequency deviation. Given gain, resistive divider calculated correct amplitude modulate VCO. peak frequency deviation measured domain modulation analyzer spectrum analyzer. loop filter modulation port VCO. With correct amplitude signal, output generates modulated signal connected input frequency doubler inside LMX3162. 2.4-GHz signal transmit output (TX_OUT) should filtered prior feeding power amplifier. Otherwise, phenomenon called spectra regrowth occurred. Bluetooth power mode, required transmit power dBm. TX_OUT provides output power level -7.5 dBm. amplifier 10.5-dB gain should sufficient 1-dB loss Transmit/Receive switch 2-dB loss post-amplifier ceramic band pass filter included. simple solution single stage amplifier with bipolar transistor8 biasing with internal voltage regulator supply LMX3162. Bluetooth high power node, power range dBm. high efficiency power amplifier should also employed. Good candidates ITT2304 Bluetooth HomeRF, ITT2302 Upbanded DECT.
same configuration LNA, Siemens BFP420, will mentioned receive section.
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FIGURE Lock Time
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FIGURE Open Loop Frequency Drift 85°C Bluetooth, maximum continuous transmit time slots, 3.125 total loop filter capacitance about needed lock time, which including budget margins programming time. Then, drift 3.125 about
6The
typical value leakage current 85°C.
which meets Bluetooth requirement kHz. This calculation tells that LMX3162 meets requirement even without additional op-amp, switch large capacitor.
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FIGURE Bluetooth Modulated Signals
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FIGURE Block. Block Removing harmonics sub-harmonics carrier filtering also necessitated after amplification because transmit spectrum regulated FCC. also requires radiated power offsets more below peak power. Figure shows PRBS15 modulated Bluetooth signal transmitter output 0.5, GFSK peak-to-peak frequency deviation) mask transmit spectrum generated ESG4433 signal generator comparison. (The trace shown Figure with larger side-lobe created from signal generator.) This indicates requirement met. wideband unmodulated transmit spectrum shown Figure sub-harmonics without post-amplifier filtering, which meets Bluetooth specification. post-amplifier ceramic filter shown Figure used receive filtering shared transmit also. phase noise satisfy certain requirements mentioned Table because open loop operation either transmit receive mode. unmodulated signal shows phase noise transmit signal Figure
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FIGURE Harmonics Transmitter Output Moreover, power supply should regulated. experiment, external noise voltage regulator, National Semiconductor LP2980, used isolate supply from transient, especially power
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amplifier. Typically, 20-dBm power amplifier draws more than voltage drop from internal resistance battery traces excess allowance without regulation. Given gain MHz/V, internal resistance Ni-MH battery used handsets about 0.25 series resistance about wide micron thick copper traces, total drop will 40.8 error budget allocates kHz, this means only allowed voltage drop.
quirements, signals feed enhance performance receiver. LMX3162 meets requirements Bluetooth HomeRF without LNA. image frequency (110 MHz). example using single bipolar transistor amplifier shown Figure gain noise figure achieved while consuming approximate 2.7-V regulated supply from LMX3162 internally.
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FIGURE Phase Noise Local Oscillator Receiver LMX3162 adopts heterodyne receiver architecture shown Figure 7(b). demodulated data obtained frequency conversions with some channel selection filtering along receiver path. antenna will perceive many frequencies air. band signals will first selected image, which MHz9 below signals, will suppressed through ceramic band-selection filter. Based sensitivity
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FIGURE LNA/.PA Low-Power Mode Once images suppressed, signals connect input 2.5-GHz mixer inside LMX3162. port mixer connected frequency doubler internally. Since MHz, frequency should below carrier frequency. mixer 15-dB gain with 13-dB noise figure, OIP3 this mixer dBm. system noise figure from filter about analysis receiver chain shown Figure
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FIGURE Receiver Chain Analysis
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FIGURE Quadrature Demodulation mixer OIP3 dBm. With OIP3 dBm10 amplifier, system OIP3 would about dBm. assume filters linear negligible nonlinearity. This indicates linearity latter stage amplifier here) more critical. After signal translated possible partially channel selection. signals band-limited filter matching network. This filter11 centered MHz, 3-dB bandwidth MHz. minimum insertion loss about filter provides selectivity prevents spurious components distort signal following stages because non-linearity. Then, signal amplified further suppressing unwanted interference external filter before feeding limiter. This because limiter large gain inherently non-linear. Even small interference possibly cause distortion. output limiter, signal strong enough discriminator translate baseband. internal 1-pF capacitor directs signal input ports discriminator external tank circuitry provides correct phase shift between inputs generate baseband signal optimum level. post-detection filtering further limits noise bandwidth configuration quadrature demodulation shown Figure automatic quadrature tank application S_field sampling initial frequency offset between transmitter receiver operated with baseband controller. description automatic tuning tank Sample-And-Hold data slicing comparison found evaluation notes.12
data sheet provide OIP3 information. typical number amplifier used illustration purpose here. SAFU110.0MSA45T 110.0 center
SAFU110.6MSA40T 110.592 center Reader find description evaluation notes.
4.3.1 Demodulation Parallel Tank quadrature tank circuit shown Figure resistor physically presented circuit. Instead, models finite value quality factor tank. principle operation that internal coupling capacitor (Cl) resonant circuit provides instantaneous phase shifts that correspond changes modulation. multiplication these quadrature signals discriminator (mixer) then generates output demodulated signal. transfer function quadrature tank derived[7],
resultant phase characteristic H(j)
LMX3162 evaluation board, internal 1-pF capacitor. tuning quadrature tank MHz, combination constant variable capacitor (2-6 pF).
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FIGURE Parallel Quadrature Tank choice inductor entails compromise among tuning range, quality factor bandwidth. Larger inductor implies higher quadrature tank well filters along receiver path determine bandwidth. Therefore, higher larger inductor means narrower bandwidth. instance, extensive filterings moderate lower noise bandwidth. Then, sensitivity inter-symbol interference both improve because signal-to-noise ratio (SNR) increases. However, bandwidth further reducing eventually chops signal bandwidth, SNR, sensitivity obviously degraded. this reason, used
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FIGURE Diagram, 4.3.2 Performance Without LNA, transceiver achieves sensitivity 1e-3, with received signal offset Bluetooth standards. This easily meets Bluetooth minimum sensitivity requirement dBm. With optimal filter, sensitivity obtained. diagram received signal 1e-3 input power shown Figures respectively. TABLE Interference Test Bluetooth Test Name Image Conditions Locked, LNA, BER=1E dBm, dBm, dBm, dBm, dBm, dBm, Result Passed Passed Passed Passed Passed Passed
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FIGURE Diagram, 1e-3,
transceiver must operate with unwanted signals either same adjacent channels. Strong band signals even desensitize radio completely. Table lists specifications test receiver various conditions.
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filter (see footnote these protocols available time measurement made. However, specific filter bluetooth available narrower bandwidth filter will improve performance LMX3162. three year relaxed specification 1-MHz test below desired signal.
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FIGURE Diagram Bluetooth Test
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FIGURE Diagram Bluetooth 2-MHZ Test (-81 dBm)
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FIGURE Diagram Bluetooth 1-MHz Test first Co-Channel Interference (CCI). radio meets 1e-3 with below desired input even power level dBm. specified desired signal level dBm, radio even meets with that only difference. this level, LMX3162 suffers degradation sensitivity. Figure shows diagram Bluetooth test. second category interference test Adjacent Channel Interference (ACI). radio must achieve individual test 1e-3 with undesired Bluetooth signals from other users 1-MHz, 2-MHz 3-MHz offset. input level interference dB13, respectively. LMX3162 meets tests. Figures show diagram test different frequency offset. radio meets relaxed specification 1-MHz offset. these experiment, cost filter bandwidth wider than Bluetooth signal bandwidth. center frequency filter used these measurements 110.6 because specific
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FIGURE Diagram Bluetooth 3-MHz Test (-72 dBm) last test shown Table measuring intermodulation properties. test measures sensitivity receiver. (BER 1e-3) with desired signal dBm, static sine wave 3-MHz offset another Bluetooth signal 4-MHz offset. intermodulation product creates interference 2-MHz offset. This frequency subsequently mixes with other input frequencies generates interference falling signal indirectly. This also degrades sensitivity receiver. result
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shown Figure captures spectrum input with signals when 1e-3 measured discriminator output.
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Bluetooth
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HomeRF/Upbanded DECT FIGURE Optional LNA/PA Bluetooth HomeRF/Upbanded DECT REFERENCE NOTES LMX3162 Datasheet. LMX3162 Evaluation Notes. Specification Bluetooth System, Version 0.9, 1999. HomeRF SWAP Specification. Document CFR47, Part Sections 15.205, 15.209, 15.247, Federal Communications Commission, USA. D.E. Fague, Karmel, "Techniques Open Loop Modulation Wideband DECT", Proceedings Expo, March 1994. Wireless Communication, Demodulating with LMX2240 Receiver, National Semiconductor Application Note AN-1020.
FIGURE Bluetooth Intermodulation Test CONCLUSION LMX3162 capable support 2.4-GHz applications. difference implementations depend various standards. Figure summaries optional devices implementing Bluetooth HomeRF/Upbanded DECT. List Materials optimized schematic shown Table Figure respectively. complete MICROWIRE programming description, LMX3162 data sheet evaluation notes.[1][2]
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TABLE Bill Materials LMX3162 Serial Number
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Used
Part Type 0.01 0.015 used 2700 1000 pF-6 LMX3162 RSSI Disc Thresh Comp 10P_HEADER 12P_Header BFP420E-6327 mmBT3904 3.3k 3.9k used
Designator
Vendor
Tolerance +/-5% +/-5% +/-5% +/-5% +/-5% +/-5% +/-5% +/-5% +/-5% +/-5% +/-5% +/-5% +/-5%
Size
C51* C52*
Murata TZBX4Z060BA110
+/-5% +/-5% +/-5% +/-5% +/-5% +/-5% +/-5%
5763SF(SMA) 5762SF(SMA) 5762SF(SMA) 5762SF(SMA) 5762SF(SMA) 5762SF(SMA) 5762SF(SMA) 5762SF(SMA) 5762SF(SMA) 5762SF(SMA) 5762SF(SMA) Common Connectors 255G HTSM 3203-40G2 Common Connectors 255G HTSM 3203-40G3 CoilCraft CoilCraft CoilCraft CoilCraft CoilCraft CoilCraft CoilCraft Siemens Fairchild +/-10% +/-10% +/-10% +/-10% +/-10% +/-10% +/-10% +/-10% +/-10% +/-10%
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TABLE Bill Materials LMX3162 (Continued) Serial Number Used 1.2k 6.8k 3.9k Trigger DFC22R44P084LHA, Murata UCVE8X805A URAE8X630B, ALPS LP2980AIM5 SAFU110.0MSA45T, Murata Part Type Designator National Semiconductor Vendor Tolerance +/-10% +/-10% +/-10% +/-10% +/-10% +/-10% +/-10% +/-10% +/-10% +/-10% Size
*All capacitors type. Capacitor (with asterisk C51, recommended lower avoid leakage. **URAE8X630B soon replaced modified version UCVE8X805A, ALPS.
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FIGURE Optimized Schematics LMX3162 Evaluation Board (include buffer)
Using LMX3162 2.4-GHz Band
Notes
LIFE SUPPORT POLICY NATIONAL'S PRODUCTS AUTHORIZED CRITICAL COMPONENTS LIFE SUPPORT DEVICES SYSTEMS WITHOUT EXPRESS WRITTEN APPROVAL PRESIDENT GENERAL COUNSEL NATIONAL SEMICONDUCTOR CORPORATION. used herein: Life support devices systems devices systems which, intended surgical implant into body, support sustain life, whose failure perform when properly used accordance with instructions provided labeling, reasonably expected result significant injury user.
National Semiconductor Corporation Americas Tel: 1-800-272-9959 Fax: 1-800-737-7018 Email: support@nsc.com www.national.com National Semiconductor Europe Fax: 180-530 Email: europe.support@nsc.com Deutsch Tel: 9508 6208 English Tel: 2171 Tel: 8790
critical component component life support device system whose failure perform reasonably expected cause failure life support device system, affect safety effectiveness.
National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: ap.support@nsc.com
National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507
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National does assume responsibility circuitry described, circuit patent licenses implied National reserves right time without notice change said circuitry specifications.

Using LMX3162 2.4-GHz Band TABLE CONTENTS ABSTRACT INTRODUCTION S

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