A Reconfigurable Continuous-Time Delta-Sigma Modulator for Dual-Mode Ultrasonic Application

The paper presents a reconfigurable continuous-time (CT) delta-sigma modulator (DSM) for dual-mode ultrasonic application. The modulator supports two operating modes: B-mode and continuous-wave (CW) Doppler mode. A low-pass DSM was designed for the B-mode operation and it can achieve a dynamic range of 62.5 dB with a signal bandwidth of 5 MHz. A band-pass DSM for the CW Doppler mode was implemented based on the low-pass modulator design. The simulated dynamic range of the band-pass DSM is 115.0 dB with a signal bandwidth of 200 kHz. By sharing most of the building blocks between the low-pass and the band-pass modulators, the overall hardware complexity as well as the power consumption can be reduced.