In-situ measurement of transducer impedance using AFE active termination through analysis of ultrasound echoes

Measurement of transducer impedance in ultrasound systems indicates both the performance of a transducer and the presence of damaged elements and cables. Load impedance analysis is typically performed with dedicated test equipment and is a time consuming and thus expensive process, especially for high channel count systems. This paper proposes a method for the measurement of channel source impedance (transducer, coaxial cable and T/R switch) through the use of an integrated receiver analogue front end with configurable termination resistance. The proposed method is first demonstrated using a pitch-catch configuration using a separate source transducer to excite the transducer under test. Subsequently the method is demonstrated the Ultrasound Array Research Platform (UARP) and a linear array transducer in a pulse echo mode where the transducer impedance is determined through the analysis of two ultrasound echoes. The proposed method is especially suited to rapid transducer testing in the field, such as in a hospital, or where access to the transducer is not possible as in many industrial processes.