Effect of the switching order on power dissipation in switched-capacitor circuits

The total power dissipation in a switched-capacitor circuit can be expresse d as the sum of two terms: the static power absorbed by the operational amp lifiers and the switching power, i.e., the power dissipated in charging and discharging the capacitors. It is shown that, in general, the switching po wer depends on the order in which the switches connected to the same clock phase are closed. In practice, it is impossible to know this order with abs olute certainty. As a consequence, a realistic estimate of the power dissip ation can only be given as a range of possible values. It is shown that upp er and lower bounds on the power dissipation can be computed by solving a s ingle-source shortest paths problem on a directed graph. Numerical results obtained on a number of switched-capacitor circuits indicate that, if low-p ower operational amplifiers are used, the switching power can be a signific ant fraction of the circuit's overall power dissipation.