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[Technical article / FAQ, rfforum Editorial Team]
At FR2, the link budget argument often stops at max EIRP and power class. On the bench and in a pocket or outdoor CPE enclosure, thermal derating usually hits first — and it looks like a PA or beamforming bug if you only watch ACLR.
1. What actually limits sustained EIRP
- PA and frontend efficiency dump heat into a small volume; sustained duty cycle and beam dwell matter more than a short peak EIRP demo
- Antenna / module integration: a lab fixture with airflow is not a sealed handset or sun-loaded CPE
- Beam codebook and duty: holding a high-gain beam while the PA stays hot is a different thermal problem than hopping beams in a traffic model
2. Freeze list for a power-class claim
- Measurement duration and duty cycle next to every EIRP / ACLR / EVM number
- Case / module temperature (or a defined proxy) at which you declare "still in class"
- Whether derating is open-loop (timer / temperature sensor) or closed-loop (power backoff from a thermistor / die sensor)
- Chamber vs conducted: OTA EIRP with a hot module can disagree with a cold conducted PA test by more than your margin
3. Habit
Log temperature + backoff state in the same row as EIRP. A pass at t=30 s and a fail at t=10 min is not "ACLR instability" — it is thermal policy you have not written down.
Discussion: when your last FR2 unit left its claimed power class, was the binding limit die temperature, module skin temperature, or a battery/PMIC rail — and do you publish a derating curve next to the EIRP headline?
— rfforum 编辑部 / Editorial Team
At FR2, the link budget argument often stops at max EIRP and power class. On the bench and in a pocket or outdoor CPE enclosure, thermal derating usually hits first — and it looks like a PA or beamforming bug if you only watch ACLR.
1. What actually limits sustained EIRP
- PA and frontend efficiency dump heat into a small volume; sustained duty cycle and beam dwell matter more than a short peak EIRP demo
- Antenna / module integration: a lab fixture with airflow is not a sealed handset or sun-loaded CPE
- Beam codebook and duty: holding a high-gain beam while the PA stays hot is a different thermal problem than hopping beams in a traffic model
2. Freeze list for a power-class claim
- Measurement duration and duty cycle next to every EIRP / ACLR / EVM number
- Case / module temperature (or a defined proxy) at which you declare "still in class"
- Whether derating is open-loop (timer / temperature sensor) or closed-loop (power backoff from a thermistor / die sensor)
- Chamber vs conducted: OTA EIRP with a hot module can disagree with a cold conducted PA test by more than your margin
3. Habit
Log temperature + backoff state in the same row as EIRP. A pass at t=30 s and a fail at t=10 min is not "ACLR instability" — it is thermal policy you have not written down.
Discussion: when your last FR2 unit left its claimed power class, was the binding limit die temperature, module skin temperature, or a battery/PMIC rail — and do you publish a derating curve next to the EIRP headline?
— rfforum 编辑部 / Editorial Team
