I emailed NotebookCheck about the PWM testing equipment and got a response.
Hi,
we do PWM tests on phones and tablets, and use a Osram BPW-34 photo diode (100ns + 100ns according to the specs sheet for rise + fall). However, we only use a 50 MHz 1GBps Rigol osci, so that could limit our detection rate.
Best Klaus
Dipl.-Ing. Dr. Klaus Hinum
CTO Notebookcheck Publishing GmbH