Hi Team,
My customer is using ADS4128 and find something strange.
The noise of ADS4128 is very big when there has no input signal (40dB); the 4 LSB has random data but not LVDS data.
The noise of ADS4128 is much smaller when there has input signal (-20dB).
Below spectrum shows nearly 60dB difference between with input signal and without input signal.
Spectrum diagram (with normal input signal):
Spectrum diagram (without input signal):
Configuration File:
# ADS4128 Registers Script # # Part: ADS4128 # Design ver: V1.00 # Creator: XXX # Created On: 2018-12-27 16:33:00 # End configuration preamble # # 0x00,0x02 //software reset ads4128 # 0x01,0x00 //lvds vdiff default 350mV # 0x03,0x00 //default performance mode # 0x25,0x00 //gain default 0db, test pattern off # 0x26,0x00 //100ohm default # 0x3D,0x00 //DFS define # 0x3F,0x00 //user define pattern # 0x40,0x00 //user define pattern # 0x41,0x09 //dfs define lvds,max strength,enable rise ,fall. # 0x42,0x00 //low latency enable(disable gain/test pattern/offset),nomal operation # 0x43, 0x03 //nomal operation,lvds swing enable # 0x4A, 0x00 //Default performance mode # 0xBF, 0x00 // Default 0 # 0xCF,0x00 // Default 0 # 0xDF,0x00 // low speed mode disable # # Start configuration registers 0x00,0x02 0x01,0x00 0x03,0x00 0x25,0x00 0x26,0x00 0x3D,0x80 0x3F,0x00 0x40,0x00 0x41,0x49 0x42,0x08 0x43,0x03 0x4A,0x00 0xBF,0x00 0xCF,0x00 0xDF,0x00 # End configuration registers
Could you help explain why there has big noise when there has no input signal? Or check if there has something wrong inside the configuration file?
thanks a lot.
Best regards,
Yang
