The addition of a top-gate to a bottom gate microcrystalline silicon thin film transistor (TFT) that is processed at a maximum temperature of 180 degrees C, is shown to lead to a very efficient control of the threshold voltage V(TH). A real time control of CMOS pairing is then possible. The value of the coupling coefficient that is the ratio of the variation of V(TH) on the variation of the voltage of the top-gate control is 0.7. This efficient control is mainly due to the use of very thin, 50 nm thick, active layer and to its electrical quality that leads to a full depletion. (C) 2011 Elsevier Ltd. All rights reserved.