The article presents implementation details of a Sigma-Delta modulator for use in ADC converters of signals with a really low amperage, i.e. up to 1 nA. The paper describes an adaptation of the moderate-inversion technique for processing biomedical signals obtained using amperometric measurements or measurements of living organisms. The analog part of the circuit operates in current mode. The modulator structure is based on a current-to-frequency converter and was designed using the classic digital 65 nm CMOS technology. The paper presents results obtained using post-layout simulations of the modulator. The modulator is able to process frequencies up to 10 kHz and is sampled with a 10 MHz frequency. SNDR was obtained at the level of 55.1 dB and SNR equaling 58.2 dB. The input impedance of the presented AFE occurs at 1 GQ. The power consumption of the whole circuit equals 276 nW and the circuit occupies 0.00442 mm2 of area, which also makes it suitable for implantable-chip applications. The paper is concluded with analyses of sensitivity of the circuit.

This paper presents a system for the remote design and testing of electronic circuits and devices with FPGAs during COVID-19 and similar lockdown periods when physical access to laboratories is not permitted. The system is based on the application of the IoT concept, in which the final device is a test board with an FPGA chip. The system allows for remote visual inspection of the board and the devices linked to it in the laboratory. The system was developed for remote learning taking place during the lockdown periods at Poznan University of Technology (PUT) in Poland. The functionality of the system is confirmed by two demonstration tasks (the use of the temperature and humidity DHT11 sensor and the design of a generator of sinusoidal waveforms) for students in the fundamentals of digital design and synthesis courses. The proposed solution allows, in part, to bypass the time-consuming simulations, and accelerate the process of prototyping digital circuits by remotely accessing the infrastructure of the microelectronics laboratory.