A combined test structure with ring oscillator and inverter chain for evaluating optimum high-speed/low-power operation

Abstract

A test structure combined with a ring oscillator, an inverter chain and an embedded monitor inverter, which allows accurate internal node access, is proposed. Vdd and well-hias dependence of gate delay and supply current measured hy both ring oscillator and inverter chain scheme. V, control method by well biasing, particularly to forward direction, is effective for high speed operation under low supply voltage. The new test structure can he utilized to evaluate optimum conditions for high-speed/low-power operations as well as high-reliability operations.