Ultrasound Transceiver Beamformer and Delay-control Scheme for a Finger Vein-pattern Sensor based on a 2D Transducer Array

Abstract

This paper proposes an ultrasound transceiver beamformer (BF) and a delay-control scheme for a finger vein-pattern sensor based on a two-dimensional (2D) transducer array. To facilitate sequential volume scanning without intermittent acquisition of delay information through external interface, delay encoding schemes for each transmitter (TX) and receiver (RX) BF are proposed. Both delay encoding schemes are based on an initialization of on-chip memory. With this delay-encoding scheme and its controller, both TX beamforming and dynamic RX beamforming can be performed sequentially for a 20 x 20 2D array. A TX BF and a RX-BF controller using onchip memory are implemented using register transfer level Verilog. Also, a delay-decoding circuit, which is based on a shift register, is implemented at the transistor level. Through RTL simulation, a sequential focusing operation of TX BF and a delay-encoding result of RX BF are illustrated. Also, a mixed-signal simulation for the BF controller along with the RX BF is performed to show a dynamic RX beamforming operation. A chip incorporating proposed TX BF and BF controller is implemented using a 180-nm (bipolar-CMOS-DMOS) BCD process. In simulation results, achieved power and active area per channel are 0.24 mW and 0.22㎟, respectively.