EVM (ERROR VECTOR MAGNITUDE) SPECIFICATION TABLE -- Required EVM per modulation per standard | IEEE 802.11-2020 Tables 17-19, 19-27, 21-29, 27-80 | For EVM Budget Calculator tool21 rows#
| Standard | MCS / Rate | Modulation | Coding Rate | Required EVM (dB) | EVM (linear %) | Engineering Notes |
|---|---|---|---|---|---|---|
| 802.11a/g | 6 Mbps | BPSK | 1/2 | -5 dBr | 56% | Easy to achieve. Any modern RF chip meets this. |
| 802.11a/g | 9 Mbps | BPSK | 3/4 | -8 dBr | 40% | |
| 802.11a/g | 12 Mbps | QPSK | 1/2 | -10 dBr | 32% | |
| 802.11a/g | 18 Mbps | QPSK | 3/4 | -13 dBr | 22% | |
| 802.11a/g | 24 Mbps | 16-QAM | 1/2 | -16 dBr | 16% | |
| 802.11a/g | 36 Mbps | 16-QAM | 3/4 | -19 dBr | 11% | |
| 802.11a/g | 48 Mbps | 64-QAM | 2/3 | -22 dBr | 7.9% | Starting to require better PA linearity. |
| 802.11a/g | 54 Mbps | 64-QAM | 3/4 | -25 dBr | 5.6% | Standard high-rate requirement. Most chipsets meet with margin. |
| 802.11n | MCS 0-2 | BPSK/QPSK | - | -5 to -10 dBr | 56-32% | Same as legacy OFDM. |
| 802.11n | MCS 3-4 | 16-QAM | - | -16 to -19 dBr | 16-11% | |
| 802.11n | MCS 5-6 | 64-QAM | 2/3 or 3/4 | -22 to -25 dBr | 7.9-5.6% | |
| 802.11n | MCS 7 | 64-QAM | 5/6 | -28 dBr | 4.0% | 802.11n peak. Slightly tighter than 802.11a/g 54Mbps. |
| 802.11ac | MCS 0-7 | BPSK to 64-QAM | - | Same as n | - | |
| 802.11ac | MCS 8 | 256-QAM | 3/4 | -30 dBr | 3.2% | 256-QAM requires <3.2% EVM. Good PA + LO quality needed. |
| 802.11ac | MCS 9 | 256-QAM | 5/6 | -32 dBr | 2.5% | Peak ac rate. Stringent EVM. Phase noise and IQ imbalance critical. |
| 802.11ax | MCS 0-9 | BPSK to 256-QAM | - | Same as ac | - | ax symbol 4x longer = better tolerance to some impairments. |
| 802.11ax | MCS 10 | 1024-QAM | 3/4 | -35 dBr | 1.8% | New in ax. Phase noise must be < -115 dBc/Hz @ 1MHz offset. |
| 802.11ax | MCS 11 | 1024-QAM | 5/6 | -35 dBr | 1.8% | IEEE 802.11ax spec EVM req = -35 dB (same as MCS10). Phase noise / IQ imbalance dominate. (Note: real silicon often targets -38 dB internally for margin.) |
| 802.11be | MCS 0-11 | Same as ax | - | Same as ax | - | be adds MCS 12/13 only new requirement. |
| 802.11be | MCS 12 | 4096-QAM | 3/4 | -38 dBr | 1.26% | New in be. Requires phase noise < -118 dBc/Hz. Not achievable in mobile devices yet. |
| 802.11be | MCS 13 | 4096-QAM | 5/6 | -38 dBr | 1.26% | Peak EHT MCS. Same -38 dB EVM limit as MCS12 (limit is per-modulation). Needs SNR ~40+ dB; near-AP only. |
EVM IMPAIRMENT BUDGET -- Component contributions to total EVM8 rows#
| Impairment | Typical Value | EVM Contribution (dB) | Affected Standards | Mitigation | - | - |
|---|---|---|---|---|---|---|
| Phase noise (LO quality) | < -110 dBc/Hz @ 1MHz offset | 2-4 dB | All, critical for 1024/4096-QAM | Better VCO/PLL design. DPD does not help phase noise. | - | - |
| IQ amplitude imbalance | < 0.5 dB amplitude mismatch | 1-3 dB | All OFDM, worse at high QAM | Digital IQ calibration at power-on. Per-temperature compensation. | - | - |
| IQ phase imbalance | < 1 degree phase error | 1-2 dB | All OFDM | Digital IQ correction. Quadrature hybrid calibration. | - | - |
| DC offset / carrier leakage | < -25 dBc from carrier | 0.5-2 dB | All OFDM (DC subcarrier) | DC calibration. DC subcarrier is null in 802.11 to mitigate. | - | - |
| PAPR clipping distortion | 3-4 dB at typical IBO | 2-5 dB | All OFDM, worse at 320 MHz | DPD (Digital Pre-Distortion): saves 3 dB IBO. Crest factor reduction. | - | - |
| ADC/DAC quantization | 12-14 bits typical | 0.5-1.5 dB | All digital | More bits reduce quantization noise. 14-bit DAC typical in premium chips. | - | - |
| TX filter group delay variation | < 1 ns across channel | 0.5-2 dB | All, worse at 160/320 MHz BW | Better filter design. Pre-distortion of group delay at edges. | - | - |
| Combined (RMS sum) at peak MCS | - | ~4-6 dB total | Must beat IEEE spec by margin | Each impairment adds in RSS (root sum of squares) fashion. | - | - |