Freescale Semiconductor,inc.

Reecha Jajodia

Gaurav Goyal

Amol Agarwal

Ateet Mishra

A scan flip-flop for generating an output signal based on a first input signal, a clock signal, a test input signal, a Launch On Shift (LOS) signal, a test enable signal, and a reset signal includes a logic circuit, a multiplexer and a flip-flop circuit. The logic circuit receives an inverted clock signal, the test enable signal, a intermediate test enable signal, and the LOS signal, and generates an intermediate output signal that is an inherent LOS scan enable signal. The multiplexer receives the test input signal and the intermediate output signal, and outputs the test input signal. The flip-flop circuit receives the test input signal as a second input signal, the clock signal, and the reset signal, and generates the output signal.

Scan flip-flop circuit with LOS scan enable signal

Spare gate cells for inclusion in an integrated circuit have multiple inputs and outputs and are capable of selectively performing, concurrently, multiple logic functions on signals appearing at the inputs. Selection of required logic functions depends on the connections of at least one of the inputs of the spare cell. One of the outputs is fed back to an input of the spare gate cell to provide certain functionality while other outputs are set to a fixed logical value. The spare gate cell may be configured to perform NOR, OR and inverter operations on inputs simultaneously.

Spare gate cell for integrated circuit

A scan flip-flop includes a multiplexer, a flip-flop, and a logic circuit. The flip-flop includes a transmission gate that has two sets of clock-controlled transistors. The combined width of the clock-controlled transistors in a set equals the width of the single transistor commonly used in known scan flip-flop circuits. The logic circuit inhibits the clock signal from reaching one transistor of each set during scan mode, which reduces power consumption without sacrificing speed of operation.

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Reecha Jajodia