Leakage current cancellation technique for low power switched-capacitor circuits

In this paper, we describe a circuit technique to implement low power switched-capacitor circuits for low frequency operation. Low power consumption is crucial for medical implant devices. Reducing supply voltage is well known to minimize power dissipation. To facilitate low voltage operations, the transistor's Vth are becoming lower and lower. Low Vth transistors have high leakage currents which impact the performance of switched-capacitor circuits, sample-and-hold amplifiers and many more. A new circuit technique is presented here to largely minimize the effective leakage current when the CMOS switch is tamed off. It employs an active feedback loop to automatically cancel both junction and sub-threshold channel leakage. By reducing the effective leakage current, the capacitors used in the circuit can be significantly reduced, hence lowering the overall power consumption. This is a general technique and can be used in various circuit applications.