Charge Injection in Current Copier Cells

The current copier cell [1] is a versatile building block increasingly used in many analogue CMOS circuits. However, charge injection, noise, Early effect and leakage current affect its accuracy. The Letter focuses on charge injection. A new model, derived from the work of Vittoz [2] and Sheu et al. [3], is presented to predict the actual partition of the injected charges. The results are compared with experimental measurements on a test circuit.