Integrated color LTV (light to voltage) sensors combine a photodiode, color filter and transimpedance amplifier, whose output is then processed by an ADC. The ams solution requires fewer components, saves board space and reduces assembly cost over a discrete photodiode approach - plus sensitive analog circuitry is integrated on-chip which improves the noise immunity. Color LTV devices are ideal for colorimetry, printing process control, display color correction, and selectively ambient light detection or rejection.
Integrated color LTF (light-to-frequency) converters provide RGB colour sensing via a photodiode grid consisting of 16 groups of 4 elements each. The output for each color is a square wave with frequency directly proportional to the intensity of the selected color. Each group consists of a red sensor, a green sensor, a blue sensor, and a clear sensor with no filter. The digital color information is input directly to a processor by sequentially selecting each color channel, then counting pulses or timing the period to obtain a value. The ams LTF approach eliminates circuitry since transimpedance amplifiers and analog-to-digital converters are no longer needed. The sensor can also be located remotely from the processor with no loss of noise immunity. Application examples include portable systems where space is critical.