Built-in self-test (BIST) algorithm to mitigate process variation in millimeter wave circuits

A novel built-in self-test (BIST) algorithm has been devised in this work. The concept of the algorithm is that process variation within a die is usually location based; it is not random. Therefore, if a low frequency ring oscillator is placed 40μm away from the transistors in an 80 GHz low noise amplifier (LNA), both the LNA and the ring oscillator undergo similar process variation in device sizes. Device variation in the ring oscillator can be predicted from it´s oscillation frequency shift. It is assumed that the amplifier´s device also vary in similar fashion. Thus, from a low frequency measurement of the ring oscillator´s frequency, the device variation in the high frequency amplifier can be estimated. This reduces the cost of high frequency measurements. The work is demonstrated in Advanced Design System (ADS) simulation.