A 0.44V-1.1V 9-transistor transition-detector and half-path error detection technique for low power applications

To reduce conservative timing margin, many timing-error detection techniques by monitoring selected critical paths had been proposed. However, traditional adaptive methods incur significant area overheads and cannot prevent the error that is forming in the current clock cycle. In this paper, a low-overhead Transition-Detector (TD) with a 9-transistor current sensing circuit is proposed. TDs are inserted at the half-path point of the critical path, so that the timing error in the current clock cycle can be prevented. To solve the increasing problems of monitoring paths due to inserted point deviations, a selection method of half-path insertion point is proposed. The proposed method effectively reduces the number of inserted TDs by up to 69% compared with the number of monitors inserted at path endpoints. Test chips employing the proposed design approach are fabricated in 40nm CMOS. Silicon measurements demonstrate that the whole design has achieved up to 50.5% energy saving with 120mV additional voltage scaling compared to the conventional worst-case design at the expense of 3.1% area overhead.