Circuitry that accepts a data input and an enable input, and generates an output sum based on the data input includes an input stage circuit that includes an input register. The input register accepts the enable input. The circuitry further includes a systolic register operatively connected to the input stage circuit, and the systolic register is operated without any enable connection. The circuitry further includes a multiplier connected to the systolic register, which is configured to generate a product value. The circuitry further includes an output stage circuit that includes an adder that calculates the output sum based least in part on the product value.

A digital filter with a pipeline structure includes processing structures timed by respective clock signals. Each processing structure in turn is formed by a number of processing modules for processing input samples. A phase generator aligns the processing modules with the input samples so that each input sample is processed by a respective one of the processing modules. An up-sampling buffer and a down-sampling buffer are used when the processing structures operate at different clock frequencies (thus implementing different clock domains) so as to convert signal samples between the clock domains for processing in the processing structures.

A specialized processing block on an integrated circuit includes a first and second arithmetic operator stage, an output coupled to another specialized processing block, and configurable interconnect circuitry which may be configured to route signals throughout the specialized processing block, including in and out of the first and second arithmetic operator stages. The configurable interconnect circuitry may further include multiplexer circuitry to route selected signals. The output of the specialized processing block that is coupled to another specialized processing block together with the configurable interconnect circuitry reduces the need to use resources outside the specialized processing block when implementing mathematical functions that require the use of more than one specialized processing block. An example for such mathematical functions include the implementation of vector (dot product) operations, FIR filters, or sum-of-product operations.

A systolic FIR filter circuit includes a plurality of multipliers, a plurality of sample pre-adders, each respective one of the sample pre-adders connected to a sample input of a respective multiplier, and an output cascade adder chain including a respective output adder connected to a respective multiplier. The output cascade adder chain includes a selectable number of delays between adjacent output adders. An input sample chain has a first leg and a second leg. Each respective one of the sample pre-adders receives a respective input from the first leg and a respective input from the second leg. The input sample chain has, between adjacent sample points in at least one of the legs, a selectable number of sample delays related to the selectable number of output delays. Connections of inputs from the input sample chain to the sample pre-adders are adjusted to account for the selectable number.

A digital filter with a pipeline structure includes processing structures timed by respective clock signals. Each processing structure in turn is formed by a number of processing modules for processing input samples. A phase generator aligns the processing modules with the input samples so that each input sample is processed by a respective one of the processing modules. An up-sampling buffer and a down-sampling buffer are used when the processing structures operate at different clock frequencies (thus implementing different clock domains) so as to convert signal samples between the clock domains for processing in the processing structures.

The present invention addresses the problem of reducing a circuit scale without causing a reduction in processing efficiency. This multi-stage filter processing method measures, at each stage, either the number of input data or the number of intermediate data that is generated by filter calculation processing during the stages before the final stage is reached. Coefficient data regulating for each stage the number of data sufficient to perform the filter calculation processing is held. Input data or the intermediate data that is generated in a current stage is held in a memory until the number of data reaches the number of data sufficient to perform the filter calculation processing in the current stage, on the basis of the coefficient data. When the number of data has reached, the filter calculation processing for the current stage is performed on the input data or the intermediate data that was held.

A digital filter with a pipeline structure includes processing structures timed by respective clock signals. Each processing structure in turn is formed by a number of processing modules for processing input samples. A phase generator aligns the processing modules with the input samples so that each input sample is processed by a respective one of the processing modules. An up-sampling buffer and a down-sampling buffer are used when the processing structures operate at different clock frequencies (thus implementing different clock domains) so as to convert signal samples between the clock domains for processing in the processing structures.

A specialized processing block on an integrated circuit includes a first and second arithmetic operator stage, an output coupled to another specialized processing block, and configurable interconnect circuitry which may be configured to route signals throughout the specialized processing block, including in and out of the first and second arithmetic operator stages. The configurable interconnect circuitry may further include multiplexer circuitry to route selected signals. The output of the specialized processing block that is coupled to another specialized processing block together with the configurable interconnect circuitry reduces the need to use resources outside the specialized processing block when implementing mathematical functions that require the use of more than one specialized processing block. An example for such mathematical functions include the implementation of vector (dot product) operations, FIR filters, or sum-of-product operations.