An accurate and matching-free threshold-voltage measurement system for floating-gate MOS transistors

Due to its programmable threshold-voltage characteristic, the floating-gate MOS transistor (FGT) plays an important role in the low-power applications. To tune the threshold voltages of FGTs accurately, a real-time system is presented to measure the threshold voltages. The system includes decoders, analog multiplexers, threshold-voltage measurement block, A/D converter and 32-bit advanced RISC machine (ARM). The feedback technique is applied so that the threshold voltages of FGTs can be measured with high accuracy. The measurement error lies in the range of +/- 0.3% with 16-bit A/D converter, and there has no constraint on the choice of capacitances between floating-gate and control-gate. The proposed measurement system does not require any matched component. The mathematical models of threshold-voltage measurement block are also presented. Thus, the accuracy of threshold-voltage measurements can be verified with these models.