Title :
A novel continuous-time common-mode feedback for low-voltage switched-OPAMP
Author :
Ali-Bakhshian, M. ; Sadeghi, K.
Author_Institution :
Dept. of Electr. Eng., Sharif Univ. of Technol., Tehran, Iran
Abstract :
A novel rail-to-rail and fast continuous-time common-mode feedback (CMFB) strategy is presented for low-voltage switched-opamp (SO) circuits. The threshold voltage change due to bulk signal is used to measure the output voltage. To satisfy speed requirements, averaging common-mode (CM) level and amplifying error signal are realized in a single block. Finally, the measured CM level is controlled by applying an error-voltage dependent current to the output nodes. As a design example, a modified low-voltage switched-opamp in a cascade 2-1 delta-sigma modulator adopting the proposed technique is presented. SPICE simulation using a 0.18 μm technology and VDD=0.9 V is provided which confirms the expected accuracy and speed of the CMFB circuitry.
Keywords :
SPICE; cascade networks; circuit simulation; delta-sigma modulation; feedback amplifiers; integrated circuit design; low-power electronics; operational amplifiers; switched capacitor networks; 0.18 micron; 0.9 V; CM level; CMFB; SPICE simulation; amplifying error signal; averaging common-mode level; bulk signal; cascade delta-sigma modulator; continuous-time common-mode feedback; error-voltage dependent current; low-voltage switched-OPAMP; low-voltage switched-opamp; output nodes; output voltage; rail-to-rail fast continuous-time common-mode feedback strategy; speed requirements; switched-capacitor circuit implementation; threshold voltage change; Capacitors; Current measurement; Error correction; Feedback circuits; Permission; Power amplifiers; Switches; Switching circuits; Threshold voltage; Voltage measurement;
Conference_Titel :
Low Power Electronics and Design, 2004. ISLPED '04. Proceedings of the 2004 International Symposium on
Print_ISBN :
1-58113-929-2
DOI :
10.1109/LPE.2004.1349354
