SBAS883A February 2018 – June 2018 OPT3101
PRODUCTION DATA.
The diode current is capacitively coupled to the AFE as shown in Figure 21. The AFE processes the input signal and produces digitized in-phase and quadrature-phase components of the input signal. The AFE has a full-scale current of 200 nA peak-to-peak and supports a photodiode capacitance up to 6 pF.
The signal-to-noise ratio (SNR) for a given signal current and sample rate can be calculated from the following equation.
where
where
where
For example, with an AFE signal current of 20 nA peak-to-peak (–20 dBFS), frame rate of 125 Hz (NUM_AVG_SUB_FRAMES = 31), SNR = 1193 = 61.5 dB. Depth noise standard deviation for this scenario is σdistance = 15 m / (2π) / 1193 = 2 mm.