Simple DSP interface for impedance spectroscopy of piezo-sensors

An interface for impedance spectroscopy measurements of piezo-sensors has been developed, for a digital signal processor of Delfino series of Texas Instruments. DAC of the interface is based on a 16-bit PWM with extra 8-bit part of “high resolution” (of picoseconds), with external simple (3-rd order) analog filter. Internal 12-bit ADC is converting at rates of up to 10 MS/s with 2 simultaneous sample-and-holds. So, with few extra components, high-performance analog interface has been “improvised” (developed and investigated) with a frequency range 10 kHz -400 kHz about 0,1% of the full scale resolution and repeatability of measurements.