Transceiver Design for CMUT-Based Super-Resolution Ultrasound Imaging

Abstract

A recently introduced structure for the capacitive micromachined ultrasonic transducers (CMUTs) has focused on the applications of the asymmetric mode of vibration and has shown promising results in construction of super-resolution ultrasound images. This paper presents the first implementation and experimental results of a transceiver circuit to interface such CMUT structures. The multiple input/multiple output receiver in this work supports both fundamental and asymmetric modes of operation and includes transimpedance amplifiers and low-power variable-gain stages. These circuit blocks are designed considering the trade-offs between gain, input impedance, noise, linearity and power consumption. The high-voltage transmitter can generate pulse voltages up to 60 V while occupying a considerably small area. The overall circuit is designed and laid out in a 0.35 μm CMOS process and a four-channel transceiver occupies 0.86 × 0.38 mm(2). The prototype chip is characterized in both electrical and mechanical domains. Measurement results show that each receiver channel has a nominal gain of 110 dBΩ with a 3 dB bandwidth of 9 MHz while consuming 1.02 mW from a 3.3 V supply. The receiver is also highly linear, with 1 dB compression point of minimum 1.05 V which is considerably higher than the previously reported designs. The transmitter consumes 98.1 mW from a 30 V supply while generating 1.38 MHz, 30 V pulses. The CMOS-CMUT system is tested in the transmit mode and shows full functionality in air medium.

Supply-Inverted Bipolar Pulser and Tx/Rx Switch for CMUTs Above the Process Limit for High Pressure Pulse Generation

“…Because of the large size of DMOS transistors, level shifters are designed as simple as possible, ensuring that IP1 and IP2 generate 40 -45 V sharp pulses with small current consumption, compared to the CMUT driving stage, as shown in Fig. 2b [22]. The control signals for N-type DMOS transistors have the additional buffers to optimize the delay difference between P-type and N-type DMOS transistors.…”

Supply-Doubled Pulse-Shaping High Voltage Pulser for CMUT Arrays

“…Note that in this case, V DD = 45 V. To achieve a compact design, simple level shifters are used in Fig. 2b, while ensuring that IN P1 and IN P2 generate 40–45 V sharp pulses with low current consumption, compared to the CMUT driving stage [11].…”

A 1.25 μJ per Measurement Ultrasound Rangefinder System in 65 nm CMOS for Explorations With a Swarm of Sensor Nodes

“…However, their maximum range is limited due to the attenuation of RF in fluids [8]. Typical US distance measurement methods exploit Time of Flight (ToF) of the US echoes coming from passive reflectors [16]- [18]. However, collisions and multipath propagation of the echoes experienced when the nodes are operated in an enclosed volume [19] increase the complexity of extracting distance information from the measurements and decrease the reliability when reconstructing the geometry of the explored volumes.…”