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

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... 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 applicationspecific integrated circuit (ASIC) in a 180-nm BCDMOS process and occupies a die area of 0.12 mm 2 . 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. Fig. 1. (a) Application scenario of an ICE probe. (b) Block diagram of the transceiver ASIC with the proposed TIA. 0018-9200 Eunchul Kang (Member, IEEE) received the B.S. and M.S. degrees in electronic engineering from Sogang University, Seoul, South Korea, in 2005 and 2007, respectively. He is currently pursuing the Ph.D. degree with the