Вероятно, уже было - Advanced Linear Devices. Много забавных аналоговых вещиц, вплоть до подстраиваемых "на месте" MOSFET сборок. Например:
Integrating Dual Slope A/D Converter
The ALD500 series is ALD's newest family of monolithic CMOS analog processor chips that implement precision, low power, low noise integrating dual slope A/D converters having a resolution of 16, 17 and 18 bits, plus sign bit and overrange bit. Ideally suited for a variety of high accuracy line powered and portable digital multimeter applications requiring 4½ and 5½ digit plus sign measurement resolution.
ALD521D 24-Bit Serial Output Digital Controller;
ALD523D 7-Digit Serial Input Display Controller;
ALD500AU/ALD500A/ALD500 Precision Integrating Analog Processors, Wide Body Package (denoted by a package code of SWC) offers Plug-in Second Source to Users of Telcom TC500 Integrating Dual Slope Front-end Chip;
ALD500RAU/ALD500RA/ALD500R Low Tempco Precision Voltage Reference Added to Integrating Dual Slope Front-end Analog Processor chip.
Есть и полуготовые платы.
https://www.aldinc.com/ald_integratingdual.php