For example, the Texas Instruments PGA460 is a 5.00 mm × 4.40 mm, 16-lead IC designed for use with transducers such as the PUI Audio UTR-1440K-TT-R 40 kHz ultrasonic transceiver. This highly integrated system- level IC provides an on-chip ultrasonic transducer driver and signal conditioner and includes an advanced digital signal processor (DSP) core (Figure 7).
The PGA460 features a complimentary low-side driver pair that can drive a transducer either in a transformer-based topology for higher drive voltages by using a step-up transformer, or in a direct-drive topology using external high-side FETs for lower drive voltages. The AFE consists of a low-noise amplifier (LNA) followed by a programmable time- varying gain stage feeding into an analog-to-digital converter (ADC).
The digitized signal is processed in the DSP core for both near-field and far-field object detection using time-varying thresholds. The time-varying gain offered by the PGA460 is a feature often used with ultrasonic transducers, whether for basic object detection or advanced medical imaging systems. It helps to overcome the unavoidable yet known-in-advance attenuation factor of the acoustic signal energy as it propagates through the medium.
Figure 7: The PGA460 is a complete interface for both transmit and receive functions of an ultrasonic transducer. It includes power drive circuitry, an AFE, and a DSP core to run related algorithms. (Image source: Texas Instruments)
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