In a medical pulse oximetry sensor (10) at least two light emitting diodes (16, 18) are disposed to emit red light and infrared light through a portion of a subject's anatomy with a typically high oxygenated blood throughput. Typically, this area is also relatively narrow, to allow the light to pass through the area with acceptable attenuation, such as a finger or an earlobe. Light emitted from the LEDs (16, 18) is incumbent upon an integrated circuit (22) printed from a single CMOS substrate (21). The integrated circuit (22) includes all preprocessing and post-processing elements needed to convert the detected light signals into a pulse oximetry measurement. These elements include a photodetector (20), a photo pre-amplifier (40), a sampler/holder (42), an analog to digital converter (44), a microprocessor (46) a rangefinder (48), a timing control circuit (50) and an LED control circuit (52). By integrating all pre and post processing functions into the carriage housing (12), the system becomes more efficient, less expensive to manufacture, and more robust to ambient light and x-ray radiation.