Other Parts Discussed in Thread: LMH6643,
Tool/software:
Hi Sir,
My customer use OPA2863 to replace LMH6643 for one year. Application about the circuit is 4 level inverting amp application (using 2 OPA2863). The first input signal might be 0.2mV, 300KHz. They get customer return about 100% failure rate by using OPA2863 machine, But product pass test if they use at least 1 LMH6643 at first and second stage.
C2 is OP2 input, C3 is OP3 input, and C4 is OP4 output. Can't measure OP1 input signal, and C1 is a test pattern signal for sensor TX.
1. Pass condition: We can get a around 20mV signal at OP2 input. And maybe OP1 input is 0.2mV
2. Normal condition: no signal be triggered
3. Moving to a place near AC switchgear. Normal condition waveform become unstable.
4. Waveform from board using OPA / LMH
5. Customer has covered their OP with shielding already.
6. If customer move their board out of switchgear (connected power by using extension cord plugged at the same electical socket) , maybe 3m distance, the failed condition will be fix.
7. Customer test radiation performance at external lab, Board using OPA2863 will have issue at 200Mhz~1GHz, but board using LMH will be faild at 900M~1GHz only.
Customer want to know
a. Is there any spec. we can check OP's radio SNR at datasheet?
b. How customer can improve their board design to prevent radio noise except shielding box?
c. Why LMH6643 have better performance to reject radiation noise than OPA2863? Is there any other newer device with good performance to replace OPA2863?
Please give comment about the condition and suggestion except using LMH6643 (customer want to have 2 source about the OP).
Thanks and regards,
Gary Teng
