WiBroReferenceDesignwiththeMAX2837

WiBro Reference Design with the MAX2837
  Abstract: The WiBro? reference design is a complete RF front-end solution designed to meet requirements for the WiBro 2.3GHz to 2.4GHz mobile WMAN (Wireless Metropolitan Area Network) standard. This reference design uses the MAX2837 direct-conversion transceiver and demonstrates a complete WiBro single-band RF-to-baseband solution. It serves as a platform for designs in muiple form factors such as CardBus, miniPCI, and custom CPE modules. The design can be easily adapted for WiBro-only 3.3V laptop applications, or WiBro-only 5.0V CPE applications.
  
  
  
  16 alt="Figure 1.The WiBro reference design features the MAX2837 direct-conversion transceiver." src="/file/tech2/circuit/2010/0203/ET327282010072300093212011060912364112353.jpg" width=598>
  Figure 1.The WiBro reference design features the MAX2837 direct-conversion transceiver.
  
  
  Important Design Features
  
  Complete RF-to-Baseband WiBro Solution
  +23dBm Transmit Power at 5% EVM and Meets Spectral Mask Requirements
  -79dBm Receive Sensitivity at 10% EVM
  60dB of Transmit Gain-Control Range
  94dB of Receive Gain-Control Range
  Optimized Low-Current Modes
  
  
  
  More detailed image (PDF, 324KB)
  Figure 2. Block diagram for the WiBro reference design.
  
  
  Lab Measurements
  Supply Current SummaryVBATT = +3.6V, VCC = +2.85V, TA = +25°C
  ParameterTest ConditionsMeasuredUnitsShutdown Supply CurrentMAX2837 and PA in shutdown; regulators and VCTCXO still active1.8mAIdle Supply CurrentMAX2837 in idle mode; PA in shutdown; regulators and VCTCXO active34.8mATransmit Supply Current16 QAM, 3/4 FEC coding rate, POUT = +24dBm, EVM = 5%392.6mAReceive Supply Current InLow-current mode79mANominal current mode96.2
  Receive SummaryVBATT = +3.6V, VCC = +2.85V, fRF = 2347MHz, VOUT = 90mVRMS, WiBro signal, RF specs are antenna referred, TA = +25°C
  ParameterTest ConditionsMeasuredUnitsDC OffsetI channels6.8mVQ channels4.5VGA Gain Step Size 2dBReceive Gain-Control RangeMax to min VGA gain61.7dBReceive LNA Gain StepAttenuation from 0dB to -16dB-15.9dBAttenuation from 0dB to -32dB32.1Gain Variation over TemperatureTA = -°C to +85°CLNA gain = 0dB-5.2dBLNA gain = -16dB-5.3LNA gain = -32dB-3Gain Variation over FrequencyfLO = 2304MHz to fLO = 2396MHz0.2dBSensitivity at Low Supply Current¹64 QAM, 3/4 FEC coding rate, 10% EVM at sensitivity-79.8dBm16 QAM, 3/4 FEC coding rate, 20% EVM at sensitivity-90.7Sensitivity at Nominal Supply Current¹16 QAM, ¾ FEC coding rate, 20% EVM at sensitivity-80.4dBm16 QAM, 3/4 FEC coding rate, 20% EVM at sensitivity-91.3¹Rx EVM limits are at BB I/Q Rx outputs, and are given in the IEEE® 802.16e specification Table 338, "Receiver SNR Assumptions." The assumption is that this EVM for this modulation rate is sufficient to meet 1e-6 BER.
  
  Transmit SummaryVBATT = +3.6V, VCC = +2.85V, fRF = 2347MHz, VIN = 90mVRMS, WiBro signal, RF specs are antenna referred, TA = +25°C
  ParameterTest ConditionsMeasuredUnitsLO LeakageQ = 640/352µA, I = 576/416µA-39.6dBcSideband SuppressionI/Q phase = -0.5°-52.5dBcTransmit Power-Control RangeIncluding PA gain step64.5dBGain Variation over FrequencyfLO = 2304MHz to fLO = 2396MHz1.9dBTransmit EVM16 QAM, 3/4 FEC coding rate, POUT = +24dBm, meeting spectral mask4.1%16 QAM, 3/4 FEC coding rate, POUT = +23dBm, meeting spectral mask3.5
  
  Transmit Operating Characteristics
  
  
  Figure 3. Output EVM for the reference design. The WiBro reference design delivers more than 23dBm of output power at the antenna, while meeting the required EVM specification of 5.5% over the entire 2.3GHz to 2.4GHz band.
  
  
  
  Figure 4. Transmit capture for the reference design. This capture shows the transmit spectrum, EVM constellation, and spectrum of the reference design at 23dBm of output power at the antenna. Measured EVM = 3.9% at 23dBm at 2.347GHz.
  
  
  
  Figure 5. 2.35GHz, 10MHz spectral mask using ETSI EN 301 021 F mask. This capture shows that the WiBro reference design meets the ETSI-EN-301-021F spectral mask at 23dBm of output power at the antenna.
  
  
  
  Figure 6. Receive gain characteristic across the 2.3GHz to 2.4GHz band. Gain variation over frequency is less than 0.2dB. Gain-control range, not including LNA gain steps, is 62dB, approximately 2dB per gain step.
  
  
  
  Figure 7. Gain characteristic across three LNA gain attenuations and temperatures. Gain variation over temperature for LNA attenuations 0dB and -16dB is approximately 5dB, and roughly 3dB for -32dB gain attenuation.
  
  
  Detailed Description
  The WiBro reference design includes the following components: MAX2837 direct-conversion transceiver, Micro Mobio MMPA372X PA, MAX8510 regulators, Murata balanced-to-unbalanced SAW bandpass filters, Hexawave HWS466 SPDT Tx/Rx switch, and Vishay Si1563DH load switch.
  
  The MAX2837 is a single-chip, wideband, direct-conversion transceiver designed for 2.3GHz to 2.7GHz WiBro and WiMax radios. The transceiver is fully equipped with an on-chip broadband VCO, fast settling sigma delta RF synthesizer, crystal oscillator, programmable lowpass filters, proprietary DC offset cancellation, I/Q error and carrier leakage detection circuits. The MAX2837 offers less than 1.4% of transmit EVM at -3dBm driver output power, and receive sensitivity better than -79dBm. When integrated with the MMPA372X PA and Murata BPF, the reference design can deliver at least 23dBm of output power at the antenna, while meeting WiBro EVM and spectral-mask requirements with margin.
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  SPI is a trademark of Motorola, Inc.
  WiBro is a trademark of the Telecommunications Technology Association, Republic of Korea.
  WiMAX is a trademark of the WiMAX Forum.
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