Abstract: A scan clock generator includes a clock signal input for receiving a clock signal, a scan shift mode signal input for receiving a scan shift mode signal, and a sequence controller coupled to the clock signal input for gating a selected number of clock signal pulses at a time to generate a sequence of nonconcurrent scan clock signals at separate outputs respectively in response to a first state of the scan shift mode signal.

Abstract: A circuit for parametric testing of an integrated circuit includes an integrated circuit having a plurality of input buffers and a plurality of XOR gates. The plurality of XOR gates have a first input that is connected to an output of one of the input buffers and having a second input that is connected to an output of a preceding XOR gate to form an XOR logic tree.

Abstract: A scan chain partition includes a serial input coupled to a scan input signal pin of a module under test; a plurality of scan sub-chains coupled to the serial input; a scan sub-chain output multiplexer coupled to the plurality of scan sub-chains for sequentially selecting a scan shift output of a single one of the plurality of scan sub-chains in response to a scan sub-chain control signal; and a scan sub-chain controller for generating the scan sub-chain control signal and for generating a scan clock signal at a scan clock input of the single one of the plurality of scan sub-chains.

Abstract: A a clock signal input for receiving a clock signal, a scan shift mode signal input for receiving a scan shift mode signal, and a sequence controller coupled to the clock signal input for gating a selected number of clock signal pulses at a time to generate a sequence of nonconcurrent scan clock signals at separate outputs respectively in response to a first state of the scan shift mode signal.

Abstract: A random access memory has an access time which is longer than the period of read input signals, for example digital video data signals, such that it cannot respond directly to the input signals. The memory has two read address inputs and two outputs which are arranged as separate channels, each of which can access any location in the memory. The access time of the memory is shorter than two input signal periods. The input signals are applied alternatingly to the read address inputs, and output signals constituted by data stored at addresses corresponding to the input signals are produced at the memory outputs by an arrangement of clocked latches such that, although two input signal periods are used for accessing each memory location, the alternating accessing using two channels enables the memory to produce output signals having the same period (at the same frequency) as the input signals.

Abstract: A phase locked loop includes a voltage controlled oscillator (VCO) for generating output VCO pulses. A frequency divider divides the VCO pulses by a variable number to produce frequency divided pulses whose phase is compared with that of input reference pulses by a phase detector. An update pulse is produced by the phase comparator having a pulsewidth corresponding to the detected phase difference. A pulse generator generates a train of update pulses having a combined pulsewidth equal to the pulsewidth of the update pulse, with the update pulses being substantially equally distributed within each period of the reference pulses to produce low output ripple. The update pulses are integrated by a loop filter to produce a D.C. control voltage that controls the VCO to vary the frequency of the VCO pulses such that the phase difference is adjusted toward zero. The frequency divider comprises a binary counter and a controller that enable the frequency divider to divide by a number N that is not a power of 2.

Abstract: A phase locked loop includes a voltage controlled oscillator (VCO) for generating output VCO pulses. A frequency divider divides the VCO pulses by a variable number to produce frequency divided pulses whose phase is compared with that of input reference pulses by a phase detector. An update pulse is produced by the phase comparator having a pulsewidth corresponding to the detected phase difference. A pulse generator generates a train of update pulses having a combined pulsewidth equal to the pulsewidth of the update pulse, with the update pulses being substantially equally distributed within each period of the reference pulses to produce low output ripple. The update pulses are integrated by a loop filter to produce a D.C. control voltage that controls the VCO to vary the frequency of the VCO pulses such that the phase difference is adjusted toward zero. The frequency divider comprises a binary counter and a controller that enable the frequency divider to divide by a number N that is not a power of 2.

Abstract: A random access memory has an access time which is longer than the period of read input signals, for example digital video data signals, such that it cannot respond directly to the input signals. The memory has two read address inputs and two outputs which are arranged as separate channels, each of which can access any location in the memory. The access time of the memory is shorter than two input signal periods. The input signals are applied alternatingly to the read address inputs, and output signals constituted by data stored at addresses corresponding to the input signals are produced at the memory outputs by an arrangement of clocked latches such that, although two input signal periods are used for accessing each memory location, the alternating accessing using two channels enables the memory to produce output signals having the same period (at the same frequency) as the input signals.