Hi,
I am debugging a customized board. It's a high speed data acquisition card with THS4509+ADS58C48+FPGA.
The amplifier is THS4509 set as 20dB gain. And ADC is ADS58C48. Four channels are used. 200MHz. LVDS is employed.
Current problem:
The output of ADC is not correct. There are lots of glitches generated by the ADC rather than the actual input signal. And the ADC cannot convert the input signal correctly.
The ADC output data captured by FPGA is shown as follow:
S_ad_1buf[2] is the third channel of ADC. The input of this channel is a five cycles sine waveform. But it's not correct.
There is no input of other channel, but the output of ADC has large amplitude glitches.
Oscilloscope picture about the ch-6 of the third channel of ADC, there is no input of ADC, but glitches exist in the output of ADC.
Debug:
The communication between ADC and FPGA is OK. The ADC registers can be configured correctly. The testpatter 010101 could be generated and acquired by the FPGA properly.
The testpattern data could be generated and acquired correctly shows both the ADC and FPGA worked normally.
But when switch the ADC to normal operation, the glitches occured and the data cannot be convert correctly.
I assume the reason maybe cause by the driver: THS4509 since the normal drive method is a transformer which is shown in the datasheet.
I have tried to adjust some configuration of THS4509, no improvement.
I don't think the THS4509 cannot be used to drive the ADC. The schematic is shown for reference.
It's highly appreciate if the specialist in TI could help me to solve this problem. Thanks
Regards,
Derek