Electrical engineering

CMOS

Noise (video)

Image (mathematics)

Preamplifier

Operational amplifier

Engineering

Low-noise amplifier

Automatic gain control

Artificial intelligence

Amplifier

RF power amplifier

Electronic engineering

Computer science

Dynamic range

Variable-gain amplifier

Transimpedance amplifier

IEEE Journal of Solid-State Circuits

This article presents a low-noise transimpedance amplifier (TIA) designed for miniature ultrasound probes. It provides continuously variable gain to compensate for the time-dependent attenuation of the received echo signal. This time-gain compensation (TGC) compresses the echo-signal dynamic range (DR) while avoiding imaging artifacts associated with discrete gain steps. Embedding the TGC function in the TIA reduces the output DR, saving power compared to prior solutions that apply TGC after the low-noise amplifier. The TIA employs a capacitive ladder feedback network and a current-steering circuit to obtain a linear-in-dB gain range of 37 dB. A variable-gain loop amplifier based on current-reuse stages maintains constant bandwidth in a power-efficient manner. The TIA has been integrated in a 64-channel ultrasound transceiver application-specific integrated circuit (ASIC) in a 180-nm BCDMOS process and occupies a die area of 0.12 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . It achieves a gain error below ±1 dB and a 1.7 pA/√Hz noise floor and consumes 5.2 mW from a ±0.9 V supply. B-mode images of a tissue-mimicking phantom are presented that show the benefits of the TGC scheme.

A Variable-Gain Low-Noise Transimpedance Amplifier for Miniature Ultrasound Probes