Signal to noise ratio of hybrid multilayer/single layer 2-D arrays

In our previous work, we examined the improved transmit sensitivity of 2-D array transducers using multilayer PZT. In receive mode, the signal to noise ratio (SNR) requires a more complex examination. Typically, a coaxial cable connects a single layer element to a preamplifier at the scanner. In this configuration, the high impedance 2-D array element is unable to drive the coaxial cable and preamplifier efficiently. In addition to signal losses, the electronic noise from the preamplifier usually dominates the thermal noise of the transducer element which reduces the SNR. In this study, a 1.5-D 7.5 MHz array element was analyzed using the KLM model. We show the receive SNR increases by 8.7 dB compared to the control when a high impedance preamplifier is placed adjacent to the single layer transducer element. The receive SNR improvement combined with the transmit improvement using multilayer PZT yields an overall improvement of 23.7 dB. A 1.5-D 1 MHz hybrid array was fabricated and tested to confirm the simulation results.