Title :
Offset-compensation of two-phase switched-capacitor filters
Author :
Signell, Svante ; Mossberg, KÅre
Author_Institution :
R. Inst. of Technol., Stockholm, Sweden
Abstract :
A method for the rejection of low-frequency and offset signals in two-phase switched-capacitor filters is described, along with the treatment of offset compensation using reset cycles. The method applies to all switched-capacitor structures where a DC-path can be found from a node inside the filter to the output. The idea is to connect an offset-free integrator in a feedback loop within the original filter structure. The net effect of the loop for continuous-time applications is an overall high-pass response. The resulting transfer-function distortion can be compensated for by making a small change in one capacitor. Design examples are given for a leapfrog and a cascaded biquad filter. Experimental breadboard designs and computer simulations have verified the applicability of the method.<>
Keywords :
cascade networks; compensation; feedback; integrating circuits; network synthesis; switched capacitor filters; DC rejection; LF signal rejection; active filters; breadboard designs; cascaded biquad filter; computer simulations; continuous-time applications; feedback loop; high-pass response; leapfrog filter; offset compensation; offset-free integrator; reset cycles; switched-capacitor filters; transfer-function distortion; two-phase filters; Application software; Capacitors; Clocks; Computer simulation; Feedback loop; Filters; Frequency; Switches; System performance; Transfer functions;
Journal_Title :
Circuits and Systems, IEEE Transactions on
