The WCS8000 is an integrated photo sensor that provides a wide range of optical sensitivity. The photo diode converts light signal to electrical signal. A transimpedance amplifier will gain the signal and convert it to a voltage output. The trans-impedance gain is autoadjustable to meet the required device sensitivity 3u W to 65u W. The low pass filter (LPF) and high pass filter (HPF) filter out the low and high frequency noise and provide the auto-gain adjustment over the required sensitivity. Conditioning circuit is added to generate a 128 KHz digital output signal with constant duty cycle. The output buff er will provide a maximum output current drive of 2mA.
Functional Block Description
The WCS8000 is an integrated photo sensor that provides the following functional blocks:
On die photo diode converts the light signal to electrical signal.
Trans-impedance with a low-pass filter with 1.4MHz cutoff frequency and an integrator feedback circuit that amplifies the signal and attenuates the low frequency component of the signal (i.e. DC, sunlight and indoor/outdoor lights).
High-pass filter to remove the DC off set and further amplifies the signal.
Automatic gain control circuit determines the gain level of the trans-impedance amplifier and high-pass filter.
Peak detector, comparator and output driver convert the peak signal into digital output signals.
Voltage reference and clock generator circuits generate the reference voltage and internal clock for the ASIC.