A Fast-Response Current Source with High-Impedance for Zero-Crossing-Based Circuits

In this paper, a high-impedance current source is developed to rapidly establish the output current. Under the framework of low bandwidth and large load capacitor, the output current can be quickly established by adding an auxiliary loop structure. Compared with the conventional current source circuit, the developed circuit reduces the design complexity and avoids the nonlinearity in zero-crossing-based pipelined Analog-to-Digital Converters (ADCs). Based on the TSMC 65 nm CMOS technology, the simulation results show that the established time is 974.2 ps with the output current of 608.8 μA. Therefore, the faster zero crossing detection can be achieved by the developed circuit, which can be applied in the high-speed and high-resolution pipelined ADCs.