An Auto-Calibrated Low-Noise Amplifier with 40 dB Continuous Time-Gain Compensation for Miniature Ultrasound Imaging Systems

Abstract

Miniaturized ultrasound imaging systems are increasingly important for applications such as catheter based diagnostics, wearable monitoring, and point-of-care interventions. A key challenge in these systems lies in the analog front end (AFE), where the large dynamic range of attenuated echo signal smust be managed without compromising noise performance or energy efficiency. Conventional architectures implement a separate low-noise amplifier (LNA) and time-gain compensation (TGC) stage, which increases both power consumption and silicon area—critical constraints in compact probes.

This thesis presents the design of an auto-calibrated low-noise amplifier with 40 dB continuous time-gain compensation, implemented in TSMC 0.18 µm BCD technology. The proposed design integrates LNA and TGC functionality into a unified architecture, reducing redundancy and improving energy efficiency. A feedback and feedforward ratiometric network based on pseudo-resistors provides dB-linear gain control, while a digital calibration loop mitigates process variation effects.

Simulation results demonstrate that the proposed design achieves an input-referred noise density of 2 𝑝𝐴/√𝐻𝑧 at7.5 MHz, a 38.35 dB gain range with +0.4/−0.7 dB accuracy, and total harmonic distortion below-30 dB, while consuming on average 1.46 mW from a ±0.9𝑉 supply and occupying a compact silicon area of 0.035 𝑚𝑚2. These results confirm the suitability of the architecture for next-generation miniature ultrasound imaging systems, where integration, noise performance, and efficiency are of paramount importance.