Freescale Semiconductor,inc.

Benjamin S Huang

Savithri Sundareswaran

Alexander Hoefler

Anis Mahmoud Jarrar

Ravi K Vaidyanathan

A method of provisioning an integrated circuit with decoupling capacitance includes identifying in an initial design of the integrated circuit lacking decoupling elements, a standard cell instance satisfying a transient power or frequency switching criteria. Based on a transient power characteristic of the standard cell instance, a decoupling capacitance requirement for the standard cell instance is determined. The decoupling capacitance requirement indicates a capacitance sufficient to bring the standard cell instance into compliance with a stability constraint on a supply voltage node of the standard cell instance. A decoupling capacitor satisfying the decoupling capacitance requirement is provisioned by appending an appropriate sized decap transistor having one or more gate electrode elements to the standard cell instance. The size of the decap transistor may be derived from the required decoupling capacitance, the amount of decoupling capacitance contributed by each gate electrode element, and the area required for each gate electrode element.

Method for provisioning decoupling capacitance in an integrated circuit

A CMOS cell incorporated on an integrated circuit including a PMOS transistor and an NMOS transistor. The current terminals of the PMOS and NMOS transistors are coupled in series between a lower voltage supply rail and a reference rail. The well connection of the PMOS transistor is coupled to an upper voltage supply rail having a voltage level greater than the lower voltage supply rail. The CMOS cell has low voltage swing and low leakage current to reduce power consumption. A second PMOS and NMOS transistor pair may be included and coupled in similar manner and to the first PMOS and NMOS pair to form a non-inverting cell. The PMOS transistors may be implemented in an N-well that is conductively tied to the upper supply voltage rail to avoid isolation barriers. The cell may be used in a clock tree to significantly reduce power consumption of the integrated circuit.

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Benjamin S Huang