Design of frequency-division multiplexing front-end receiver electronics for CMUT-on-CMOS based intracardiac echocardiography

Designing Intracardiac Echocardiography (ICE) imaging catheters using 2D arrays with large number of elements is extremely challenging with standard interconnect and transducer technology. Using microbeamformers inside the catheter reduces the number of cables; however it requires complex front-end electronics which consumes considerable amount of real estate. By using the CMUT-on-CMOS technology, one can incorporate on-chip transmit electronics and efficiently optimize the 2D transducer array to use less number of active elements to reduce the number of cables by combining multiple channels on a single output cable. Reducing the number of cables with integrated electronics may provide a flexible catheter which can be used for 3D ICE imaging under MRI as well as X-Ray. In this study, we explore the design of the CMOS receiver circuit which implements a Frequency Division Multiplexing (FDM) scheme to achieve reduced number of output channels. We discuss design details of an 8×1 multiplexing chip designed in 0.35μm CMOS process. We also present post layout simulation results from the chip showing the viability of the approach.