Title :
Analysis of switched-capacitor common-mode feedback circuit
Author :
Choksi, Ojas ; Carley, L. Richard
Author_Institution :
Electr. & Comput. Eng. Dept., Carnegie Mellon Univ., Pittsburgh, PA, USA
Abstract :
A detailed analysis of the dc behavior of switched-capacitor common-mode feedback circuit (SC-CMFB) is presented. A mathematical model, useful for analysis, is developed and the expressions for the output common-mode (CM) voltage, with and without considering the charge injection of switches and leakage currents, are derived. Further, the expression for dc CM settling time, is presented. The effect of parasitic capacitances, dc CM gain, charge injection error, and leakage currents, on the steady-state value of the dc CM voltage is analyzed and design guidelines to minimize these errors are presented. Finally, an improved version of the SC-CMFB circuit is analyzed. This circuit has very low errors due to charge injection and leakage currents and settles much faster than the traditional SC-CMFB circuit.
Keywords :
analogue integrated circuits; charge injection; differential amplifiers; equivalent circuits; feedback amplifiers; leakage currents; switched capacitor networks; DC behavior; analog integrated circuits; charge injection; comparison amplifier; design guidelines; fully-differential circuits; half-circuit equivalent model; leakage currents; mathematical model; output common-mode voltage; parasitic capacitances; switched-capacitor common-mode feedback circuit; Circuit analysis; Feedback circuits; Guidelines; Leakage current; Mathematical model; Parasitic capacitance; Steady-state; Switches; Switching circuits; Voltage;
Journal_Title :
Circuits and Systems II: Analog and Digital Signal Processing, IEEE Transactions on
DOI :
10.1109/TCSII.2003.820253
