As Moore's law approaching its end,electronics is hitting its power,bandwidth,and capacity limits.Photonics is able to overcome the performance limits of electronics but lacks practical photonic register and flexible control.Combining electron-ics and photonics provides the best of both worlds and is widely regarded as an important post-Moore's direction.For stability and dynamic operations considerations,feedback tuning of photonic devices is required.For silicon photonics,the thermo-optic effect is the most frequently used tuning mechanism due to the advantages of high efficiency and low loss.However,it brings new design requirements,creating new design challenges.Emerging applications,such as optical phased array,optical switches,and optical neural networks,employ a large number of photonic devices,making PCB tuning solutions no longer suit-able.Electronic-photonic-converged solutions with compact footprints will play an important role in system scalability.In this pa-per,we present a unified model for thermo-optic feedback tuning that can be specialized to different applications,review its re-cent advances,and discuss its future trends.