ZHCSSI3 February 2024 ADS1288
PRODUCTION DATA
Table 9-1 lists the effect of geophone source resistance (RS) and the effect of input current noise to total noise performance. Geophone RS = 1000Ω, 5000Ω, and two values of input current noise taken from the input current noise distribution of Figure 9-2. Input current noise values = 1.5pA/√Hz and 3pA/√Hz are evaluated. Geophone RS thermal noise, current noise × RS, and ADC input-referred noise are summed to derive total noise.
RS (Ω) | GAIN | RS NOISE (μV) | in NOISE (pA/√Hz) | in × RS NOISE (μV) | ADC NOISE (μV) | TOTAL NOISE (μV) |
---|---|---|---|---|---|---|
1000 | 1 | 0.06 | 1.5 | 0.024 | 1.4 | 1.4 |
0.06 | 3 | 0.048 | 1.4 | |||
16 | 0.06 | 1.5 | 0.024 | 0.28 | 0.29 | |
0.06 | 3 | 0.048 | 0.29 | |||
5000 | 1 | 0.13 | 1.5 | 0.11 | 1.4 | 1.41 |
0.13 | 3 | 0.22 | 1.41 | |||
16 | 0.13 | 1.5 | 0.11 | 0.28 | 0.33 | |
0.13 | 3 | 0.22 | 0.38 |
The analysis data is over a 206Hz noise bandwidth (fDATA = 500SPS). The data shows the greatest of the total noise increase compared to ADC noise alone is with 5000Ω geophone source resistance, PGA gain = 16, and in = 3pA/√Hz. The 1000Ω geophone source resistance shows an insignificant noise increase under the same condition.