An 0.8 /spl mu/m CMOS mixed analog-digital integrated audiometric system

Modern medical instruments used for audiometric tests (audiometers) require high-quality audio signals and sophisticated signal processing. During audiometric tests, indeed, the human ear is stimulated with complex modulated sinusoidal signals or masking signals (noise), to identify hearing defects or losses that can be corrected with hearing aids. The evolution of hearing aid devices from simple amplification stages to sophisticated equalizers requires a substantial improvement in the quality of the audiometric tests, to accurately customize the frequency response and optimize the hearing defect correction. The audiometers used to date based on analog components, are no longer sufficient in terms of accuracy and precision. This mixed analog/digital integrated audiometric system generates the complete set of audio and control signals required for an exhaustive audiometric test. The block diagram of the chip is shown. The system is divided into five main functional blocks: a standard microprocessor interface (bus), the digital signal generator, switched-capacitor (SC) and continuous-time (CT) filters and two separated analog signal processing channels (Left and Right).