Dynamic Circuit with Multiple Feedback Devices
Original Publication Date: 2000-Oct-01
Included in the Prior Art Database: 2003-Jun-20
Disclosed is a dynamic circuit that avoids noise-induced failures by using multiple feedback devices. Typically, dynamic circuits have one "weak" feedback to the precharge node maintaining the stored charge, Figure 1. The charge supplied by the weak feedback device adversely affects the performance of the circuit. The larger the size of the feedback device, the greater is the delay through the circuit. Therefore, the tradeoff between the performance impact of sizing the feedback larger versus the risk of noise problems if the feedback device is too small must be made during the design. It is desired to have some method of providing more feedback when more is needed and performance is not a concern (for example, under reliability stress conditions) and providing less feedback when less is needed to maintain function and less is desirable for performance reasons. The general topology of a domino logic gate using the invention is shown in Figure 3. Test input signals (T0, T1,... Tn) are used to control which extra feedback device(s) P0, P1, P2,,...Pn in Figure 3 are turned on. The feedback devices can be sized such that they supply an amount of current to the precharge node (X) that is proportional to the binary value of the test signals. An example of this is shown in Table 1. This invention does not require the binary sizing. To reduce capacitance on the output node OUT, the devices Pn+1, Pn+2,...Pn+n+1 can be sized small and P0, P1, P2,...Pn can vary in sizes.