Reference Design for an 802.11b/g RF Front-End Module Using the MAX2830
Figure 1. The reference design board shows the MAX2830 in an 802.11b/g RF front-end module
Important Design Features:
- Cascaded Receive Noise Figure of 6dB
- Low Phase Noise of -95dBc/Hz at 10kHz Offset
- Rx EVM < 9% at -74.5dBm with an 802.11g 54Mbps OFDM Signal
- 95dB Receive Gain Control Range (32dB RF and 63dB BB VGA)
- Tx EVM < 5.6% at 15dBm Output Power with an 802.11g 54Mbps OFDM Signal
- 25dB Transmit Gain Control Range
- Supports Full-Range 802.11b/g Data Rates
- Small 11mm x 16mm Size
- Low BOM Cost
Figure 2. Block diagram for the 802.11 b/g RF module
Lab Measurements
DC Performance
VBATT = +3.3V, VCC = +2.85V, TA = +25°C
Receive Summary
VBATT = +3.3V, VCC = +2.85V, fRF = 2437MHz, RF input = 802.11a, 64QAM, 54MBps at antenna, VOUT = 112mVRMS at RXI and RXQ baseband outputs, RXHP = 0, TA = +25°C
Transmit Summary
VBATT = +3.3V, VCC = +2.85V, fRF = 2437MHz, baseband inputs = 110mVRMS, 802.11a, 64QAM, 54MBps, Tx output measured at Antenna 1, RXHP = 0, TA = +25°C
| Parameter | Test Condition | Meas. | Unit | |
|---|---|---|---|---|
| Frequency Range | 2.4 to 2.5 | GHz | ||
| Receive EVM | Max Gain, VGA adjusted for VOUT = 112mVRMS, PIN = -65dBm | 3.9 | % | |
| Mid Gain, VGA adjusted for VOUT = 112mVRMS, PIN = -45dBm | 2.5 | |||
| Min Gain, VGA adjusted for VOUT = 112mVRMS, PIN = -10dBm | 2.7 | |||
| Sensitivity | Receive EVM = 9% | Antenna 1 | -73 | dBm |
| Antenna 2 | -74.5 | |||
Transmit Summary
VBATT = +3.3V, VCC = +2.85V, fRF = 2437MHz, baseband inputs = 110mVRMS, 802.11a, 64QAM, 54MBps, Tx output measured at Antenna 1, RXHP = 0, TA = +25°C
| Parameter | Test Condition | Meas. | Unit | |
|---|---|---|---|---|
| Maximum Transmit Output | Tx VGA adjusted for EVM = 5.6%, Tx VGA = -4dB | 15 | dBm | |
| ACPR | Tx VGA set for EVM < 5.6%, channel BW = 20MHz | fOFFSET = 20MHz | 36 | dBc |
| fOFFSET = 40MHz | 55 | |||
| fOFFSET = 60MHz | 60 | |||
Figure 3. Phase noise plot of the reference design
Detailed Description
The MAX2830 is a single-chip, single-band, Dual Mode™ direct-convert transceiver designed for a 2.4GHz 802.11b/g (OFDM and CCK) WLAN application. The device integrates all the circuitry required to implement the complete RF transceiver function: PA, T/R switch, antenna diversity switch, LNA, 50Ω matching components, sigma-delta fractional synthesizer, crystal oscillator, and unique I/Q amplitude and phase-error calibration circuits. The device also eliminates the need for external SAW filters by implementing on-chip monolithic filters for both receiver and transmitter. The baseband Tx and Rx filters are optimized to meet the 802.11g IEEE standard. With an additional RF filter and several passive components, one can form a complete 802.11b/g WLAN RF front-end solution that delivers high performance within a small form factor and low price.
Application Note Links
Application note 3630, "Power Supply and Ground Design for a WiFi Transceiver"
Dual Mode is a trademark of Maxim Integrated Products, Inc.
IEEE is a registered service mark of the Institute of Electrical and Electronics Engineers, Inc.
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