Kyeongwon Jeong

This article presents a discrete-time <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta \Sigma $ </tex-math></inline-formula> modulator (DSM) with a wide linear input range and high input impedance for biomedical signal acquisition. The proposed integrated circuit (IC) is based on a 1st-order DSM with 2nd-order noise-shaping (NS)-successive approximation (SAR) for high resolution with high power efficienc

This letter presents a neural stimulation IC for the 32-channel cochlear implant system. A zoom current DAC (I-DAC), whose full range is reconfigured to fit the interval between the comfort (C) and threshold (T) levels, is introduced for high-resolution stimulation strength control to provide high-fidelity sound perception with minimal hardware overhead. The IC also includes an in-situ neural recording function. The effectiveness of auditory nerve stimulation is validated by monitoring electrica

This paper presents a PVT-robust error-feedback (EF) noise-shaping SAR (NS-SAR) ADC for direct neural-signal recording. For closed-loop bidirectional neural interfaces enabling the next generation neurological devices, a wide-dynamic-range neural recording circuit is required to accommodate stimulation artifacts. A recording structure using an NS-SAR ADC can be a good candidate because the high resolution and wide dynamic range can be obtained with a low oversampling ratio and power consumption.

This article presents an ultrasound (US) transceiver IC including a highly power-efficient US receiver (RX) and a high-voltage (HV) US transmitter (TX) for US capsule endoscopy (USCE) systems for the first time. The proposed USCE system employs the developed IC, a single-element piezoelectric transducer (PZT), and a mechanically rotating reflector to obtain 360° transmural scans while traveling through the gastrointestinal (GI) tract. Since the USCE system operates with a tiny battery, power eff

We present a 600mV <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PP</inf> -linear-input-range 94.5dB-SNDR NS-SAR-based DSM with input-impedance (Z <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IN</inf> ) boosting for biopotential recording. The proposed direct-conversion ADC utilizes a 1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup> -order DS

This brief reviews the principle and design of dynamic range (DR) enhancement techniques for artifact-tolerant biopotential-acquisition ICs. In order to record small input signals without being disturbed by large artifacts, which may arise from motion or stimulation, biopotential-acquisition ICs for wearable devices and bidirectional neural interfaces should have wide DR in addition to low noise and high power efficiency. This review discusses key features of DR enhancement techniques based on t

Neural-recording ICs have been a key tool to unravel the mystery of the human brain and find treatments for various neurological diseases. Since neural signals inherently have a small amplitude and suffer from environmental interferences, conventional neural recording circuits have been mainly designed for low noise, high CMRR, and low power, using the structure with a high-gain amplifier and a low-resolution ADC [1] (Fig. 1). With the advent of closed-loop neurotherapeutics, stimulation artifac

Bio-signal monitoring systems have recently been widely applied to implantable and wearable devices for healthcare applications. However, they require extremely low-noise front-end circuits to ensure reliable recording while receiving a very small signal (e.g., the amplitude of the EEG ranging from 1 to 100µV [1]). A conventional analog front-end typically achieves a low input-referred noise (IRN) of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$

Ultrasound (US) imaging has emerged as a promising solution for medical diagnosis with its low cost and biocompatibility. Recent demands for multi-dimensional imaging in medical diagnosis brought a challenge of operating multiple US transducers, especially within miniaturized probes. There have been some studies of US systems for the application of intracardiac echocardiography (ICE) [1] and transesophageal echocardiography (TEE) [2] that require highly integrated systems within miniaturized pro

Biomedical applications of ultrasound (US) imaging have been extended and diversified. Some recent applications, such as intracardiac echocardiography [1], [2] and the intravascular US [3], require extreme miniaturization of the US imaging system. As another promising application, an ultrasound capsule endoscopy (USCE) is being developed to provide transmural scans of the gastrointestinal tract and enable the detection of deeper pathology [4]. However, the USCE has only been studied by focusing

According to the WHO report, the hearing-impaired population in the world is about 470 million in 2019, and about 15 million people could hear sounds with cochlear implants (CIs). In clinical practices, people who have a hearing loss greater than 90dB are guided to use CIs instead of hearing aids to restore hearing. The CI delivers electrical stimulation to auditory nerves through an electrode array which is surgically inserted in a cochlea. The multiple electrodes in the array are placed at dif

This work presents a 3rd-order noise-shaping successive approximation register (NS-SAR) analog-to-digital converter (ADC) employing an error feedback-cascaded integrator feedforward (EF-CIFF) structure where a low-noise amplifier (LNA) is embedded, which operates for neural recording at a low oversampling ratio (OSR). By employing the 3rd-order EFCIFF NS-SAR ADC and embedded low-gain LNA, it achieves low input-referred noise (IRN) while offering a sufficiently wide input range so that stimulatio

Capacitive sensors are widely used to acquire various types of physical information. A wide-input-range fast-conversion capacitance-to-digital converter (CDC) with high resolution and energy efficiency can accommodate such diverse applications. Among prior CDC topologies, SAR [1]–[4] and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta\Sigma{M}$</tex> CDCs [5]–[10] show high energy efficiency, but their input range is limited by the voltage s

In this letter, we present an ultrasound (US) imaging system with a low-noise US receiver (RX) and an element-level US transmitter (TX) for a capacitive micromachined ultrasonic transducer (CMUT). The proposed US RX isolates the input parasitic capacitance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(C_{P})$ </tex-math></inline-formula> from the front-end transimpedance stage by using a bandwidth-enhanced