Design of a Self-Built Bidirectional Multi-Slope Integrating Analog-to-Digital Converter

In order to meet the requirements of high-precision and high-resolution measurement environments, this paper proposes a bidirectional multi-slope integrating ADC based on the Multi-Slope III technique. The paper details the design methodology and operational principles centered on the ‘multiple integration and high-bit sampling integration with low-bit residual detection’ mode, and rigorously derives the theoretical integration waveform along with the dependence of resolution on signal integration time settings. When the signal integration time is set to one power-line cycle (PLC) with a 10 V full-scale DC input, the integrated voltage waveform exhibits stable settling with negligible distortion, confirming effective suppression of nonlinear errors. Combined with the designed optimization schemes such as the “balanced circuit” and “power frequency cycle-matched integration time”, zero-adjustment errors and power frequency interference are effectively suppressed, further improving the measurement resolution to 7.5 bits. The bidirectional integration mechanism adopted expands the input range to −10 V to +10 V, eliminating the need for excessive reliance on external signal conditioning circuits. This architecture demonstrates significant utility in low-frequency, high-resolution measurement systems.