LMG1020EVM-006: LMG1020EVM-006 problem, input J2

Part Number:LMG1020EVM-006

I try to evaluate LMG1020EVM-006, but it did not work.

I wire bonded the anode of VCSEL to anode pads of EVM, and use silver epoxy to attach the bottom of VCSEL (cathode) to cathode pad of EVM.

I did the R10 and R3 rework to bypass the pulse shortener.

And I replaced the LDO with the new ones TI sent to me (with higher voltage setting).

I make sure the signal and ground are connected correctly.

I followed the steps on the user’s guide:

1, power up DC bias supply J1 at 5.5V, set current limit to 0.1A

2, connect function generator, set frequency to 100kHz, pulse width 100ns, signal at 3V, enable the output

3, power up input supply J2 at 10V, current limit at 0.1A (last time when I tested the old board,  the voltage on input power supply is ~1.8V with current limit at 0.1A.)

But there is still problem. When I turned on input supply J2, the power dropped to ~0.1V (set at 10V), it hits the current limit 0.1A.

The voltage between TP1 and PT3 GND is 5V.

BTW, I measured the resistance between the anode pad and cathode pad of my laser is ~1.2 Ohm, which is ok.

Could you help me?

Thanks!

Tao