An open loop analog-to-digital converter based on ring voltage-controlled oscillator (VCO-based ADC) is presented. By introducing the inverse R–2R pre-weighted front-end technique, the nonlinearities of the voltage to frequency conversion of the proposed VCO is kept less than 1% over rail-to-rail input swing. Unlike prior approaches, this proposed method does not suffer from any stability issues or feedback imperfections. A prototype was fabricated using TSMC 65 nm process. It occupies an actives area of 0.03 mm² and consumes as little as 3.1 mA from 1 V power supply. Measurement results of linearity indicate SFDR and SNDR of 77 and 66.7 dB, respectively, over 5 MHz passband bandwidth. This reveals energy less than 0.2 pJ/step.

提出了一种基于环形压控振荡器的开环模数转换器（基于VCO的ADC）。通过引入反向R–2R预加权前端技术，在轨到轨输入摆幅范围内，拟议VCO的电压至频率转换的非线性度保持小于1％。与现有方法不同，该提出的方法没有任何稳定性问题或反馈缺陷。使用TSMC 65 nm工艺制造了原型。它的有效面积为0.03 mm ²，从1 V电源消耗的电流仅为3.1 mA。线性度的测量结果表明，在5 MHz通带带宽上，SFDR和SNDR分别为77和66.7 dB。这表明能量低于0.2 pJ /步。