This paper presents the design of an integrated current-controlled oscillator (CCO) based readout front-end for neurochemical sensing applications. The readout front-end chip is implemented in 65 nm CMOS technology and occupies an area of 0.059 mm 2 . The proposed design supports an input current range of 1.2 µA (±600 nA) and can also be configured to support wider current range. The CCO-based structure utilized in this design results in noise averaging of the detected neurochemical input signal due to its inherent ∆Σ first-order noise shaping and anti-alias filtering characteristics. Thus, the prototype chip achieves a current resolution of 100 pA and can detect dopamine concentrations as small as 10 µMol based on measured data from novel diamond-like carbon electrodes. In addition, the digital codes obtained from the readout front-end attain a signal-to-noise (SNR) of 82 dB and linearity limited effective-number-of-bits (ENOB) of 8 at full current range input, without employing any calibration or linearization techniques. The proposed read-out front-end consumes 33.7 µW of power in continuous operation.

A 100 mV, output-capacitorless low-dropout (OCL-LDO) regulator for UHF-RFID System-on-Chip applications is presented in this paper. The regulator utilises a 134nA twostage error amplifier with two high frequency compensation amplifiers to increase the limited PSR of the 10 pF load capacitor. The DC PSR performance is maximized with a feed-forward path in the error amplifier. The circuit is able to provide a maximum load current of 4mA, however a feed-forward PSR mechanism optimises the performance to 1mA load conditions. Due to the added feedback compensation amplifier, the twostage error amplifier does not require additional compensation network.

This paper describes a voltage controlled oscillator (VCO)-based ADC for biomedical applications which employs a relaxation oscillator for voltage-to-frequency conversion. The proposed circuit uses a redundant pair of capacitors to mitigate the conversion error resulting from the time required for resetting the capacitor. A switch matrix with feedback helps sustain oscillations. Further, the VCO frequency approaches zero as the input voltage approaches zero unlike a converter with ring oscillator, thereby reducing power consumption. Post-layout simulation of the proposed ADC designed with a 28 nm FDSOI CMOS technology shows an ENOB of 8 and power consumption of 12 W from a 0.7 V supply.

This paper describes the design of an integrated sensor interface for dopamine detection. The sensor interface circuit fabricated in 65 nm CMOS technology utilizes a timebased analog-to-digital conversion circuit built around a ring oscillator. The circuit supports a wide input current range of ±1.2 µA and sampling rate of 1-20 kHz, enabling subsecond detection of neurochemicals within the supported current range. Measured results with physiologically relevant dopamine concentration of 500 nM demonstrate the ability of the sensor interface circuit to detect oxidation and reduction current peaks, which provides information about the release times and redox potentials of the neurochemical. This chemical information is essential in neurostimulation treatment of neurological and neurodegenerative diseases.

This paper describes the design of an integrated sensor interface for neurochemical signal acquisition. Neurochemicals undergo oxidation and reduction reactions in the presence of an action potential. Thus, knowledge of the oxidation and reduction potentials of neurochemicals is important in the neurostimulation treatment of neurological and neurodegenerative diseases. The sensor interface circuit utilizes a mixed-signal design to detect the induced current from the neurochemical, in response to an applied voltage. The circuit is fabricated in 65nm CMOS technology and supports a wide input current range of ±1.2µA with a current resolution of 85.4pA, enabling detection of neurochemicals within the supported current range. Measured results with dopamine concentration of 500nMol demonstrate the ability of the sensor interface circuit to detect oxidation and reduction current peaks, indicating the release times and the required oxidation and reduction potentials for neurostimulation of the neurochemical.