Phase Noise → Jitter & EVM
Integrate phase noise to compute RMS jitter and EVM. Enter L(f) values at up to 8 frequency offsets — the tool fits a Leeson model, integrates the phase noise spectrum and computes jitter (ps), EVM (%), carrier-to-noise ratio and BER penalty for common modulation schemes.
Enter phase noise (dBc/Hz) at each offset. Leave unused rows blank.
φrms = √(2 × ∫f1f2 10^(L(f)/10) df) [radians]
EVM(%) = 100 × φrms (rad)
RMS Jitter = φrms / (2πf0) [seconds]
EVM → C/N: C/N = −20·log(EVM/100) dB
Reciprocal mixing: L(fblocker) + Pblocker must be below noise floor
| Modulation | EVM Limit | Your EVM | Margin | Standard |
|---|
Phase Noise to Jitter and EVM — Guide
Phase noise and jitter are two representations of the same phenomenon — random phase fluctuations of an oscillator or clock. Phase noise L(f) is measured in the frequency domain (dBc/Hz vs offset frequency), while jitter is measured in the time domain (picoseconds RMS or peak-to-peak). EVM (Error Vector Magnitude) is the impact of phase noise on the demodulated signal constellation.
Converting Phase Noise to Jitter
The relationship is: φ_rms = √(2 × ∫ 10^(L(f)/10) df) radians. The factor of 2 accounts for both sidebands (single-sideband phase noise L(f) is typically specified). Once φ_rms is known, RMS jitter = φ_rms / (2πf_0) seconds. For a 2.4 GHz carrier with φ_rms = 0.01 rad, jitter = 0.01/(2π×2.4e9) ≈ 0.66 ps RMS.
EVM Requirements
Higher-order modulation schemes require much lower EVM to achieve acceptable BER. 16-QAM requires EVM < ~8% (3GPP LTE), 64-QAM requires < ~3.5%, and 256-QAM requires < ~1.7%. 5G NR 256-QAM at 3.5 GHz requires very low phase noise from the LO — typically better than −100 dBc/Hz at 100 kHz offset and −130 dBc/Hz at 1 MHz.
Reciprocal Mixing
When a strong out-of-channel blocker mixes with the LO phase noise tail, it creates noise in the desired channel. The interference power = P_blocker + L(f_separation). This sets the minimum required LO phase noise at the blocker offset frequency. The 3GPP blocking specifications directly drive LO phase noise requirements in cellular receivers.