Altera Corporation

Yi-Wen Lin

Martin Langhammer

Keone Streicher

Hyun Mo Yi

David Lewis

Volker Mauer

Henry Y Lui

Triet M Nguyen

Suleyman Sirri Demirsoy

Wai-Bor Leung

Kwan Yee Martin Lee

David Edward Jefferson

Changsong Zhang

Michael David Hutton

Srinivas T Reddy

Juju Joyce

David Neto

Kumara Tharmalingam

Orang Azgomi

Dan Mansur

Configurable specialized processing blocks, such as DSP blocks, are described that implement fixed and floating-point functionality in a single mixed architecture on a programmable device. The described architecture reduces the need to construct floating-point functions outside the configurable specialized processing block, thereby minimizing hardware cost and area. The disclosed architecture also introduces pipelining into the DSP block in order to ensure the floating-point multiplication and addition functions remain in synchronicity, thereby increasing the maximum frequency at which the DSP block can operate. Moreover, the disclosed architecture includes logic circuitry to support floating-point exception handling.

Programmable device implementing fixed and floating point functionality in a mixed architecture

Digital signal processing ('DSP') circuit blocks are provided that can more easily work together to perform larger (e.g., more complex and/or more arithmetically precise) DSP operations if desired. These DSP blocks may also include redundancy circuitry that facilitates stitching together multiple such blocks despite an inability to use some block (e.g., because of a circuit defect).

Digital signal processing circuitry with redundancy and bidirectional data paths

Digital signal processing ('DSP') circuit blocks are provided that can more easily work together to perform larger (e.g., more complex and/or more arithmetically precise) DSP operations if desired. These DSP blocks may also include redundancy circuitry that facilitates stitching together multiple such blocks despite an inability to use some block (e.g., because of a circuit defect). Systolic registers may be included at various points in the DSP blocks to facilitate use of the blocks to implement systolic form, finite-impulse-response ('FIR'), digital filters.

Modular digital signal processing circuitry with optionally usable, dedicated connections between modules of the circuitry

A specialized processing block for a programmable logic device includes circuitry for performing multiplications and sums thereof, as well as circuitry for performing floating point operations. The floating point circuitry preferably includes rounding and normalization circuitry. To perform mantissa multiplications, the floating point circuitry preferably relies on the aforementioned multipliers of the specialized processing block.

Specialized processing block for programmable logic device

A specialized processing block for a programmable logic device includes circuitry for performing multiplications and sums thereof, as well as circuitry for rounding the result. The rounding circuitry can selectably perform round-to-nearest and round-to-nearest-even operations. In addition, the bit position at which rounding occurs is preferably selectable. The specialized processing block preferably also includes saturation circuitry to prevent overflows and underflows, and the bit position at which saturation occurs also preferably is selectable. The selectability of both the rounding and saturation positions provides control of the output data word width. The rounding and saturation circuitry may be selectably located in different positions based on timing needs. Similarly, rounding may be speeded up using a look-ahead mode in which both rounded and unrounded results are computed in parallel, with the rounding logic selecting between those results.

A specialized processing block for a programmable logic device incorporates a fundamental processing unit that performs a sum of two multiplications, adding the partial products of both multiplications without computing the individual multiplications. Such fundamental processing units consume less area than conventional separate multipliers and adders. The specialized processing block further has input and output stages, as well as a loopback function, to allow the block to be configured for various digital signal processing operations.

Adder/rounder circuitry for use in a programmable logic device computes a rounded sum quickly, and ideally within one clock cycle. The rounding position is selectable within a range of bit positions. In an input stage, for each bit position in that range, bits from both addends and a rounding bit are processed, while for each bit position outside that range only bits from both addends are processed. The input stage processing aligns its output in a common format for bits within and outside the range. The input processing may include 3:2 compression for bit positions within the range and 2:2 compression for bit positions outside the range, so that further processing is performed for all bit positions on a sum vector and a carry vector. Computation of the sum proceeds substantially simultaneously with and without the rounding input, and rounding logic makes a selection later in the computation.

Adder-rounder circuitry for specialized processing block in programmable logic device

Clocks are distributed efficiently to regions of a specialized processing block in a PLD. Multiple clocks are selected from a larger universe of clocks and distributed to the specialized processing block, but the choices of clocks at the individual functional regions, or stages of functional regions, are less than fully flexible. In some cases, an entire region may use one clock. In another case, portions of a stage within a region that previously had been able to select individual clocks must use one clock for the entire stage. In another case, only a subset of the selected clocks is available for a particular region, but that subset is flexibly distributable within the region. In another case, a clock may be selectable for each stage of each functional region directly from the larger universe of available clocks, avoiding the need for circuitry to select the multiple clocks from the larger universe.

Clock distribution for specialized processing block in programmable logic device

Techniques are provided for synchronously transmitting data in parallel from an external memory device to a destination circuit using a sequential read mode. The memory device includes an address counter. The address counter generates sequential read addresses for the data bits stored in the memory device. The destination circuit generates a clock signal that controls the address counter. The destination circuit can also transmit a start address to the memory device. The address counter sequentially generates a new read address in response to transitions in the clock signal beginning with the start address. Data bits are transferred in parallel from the memory device to the destination circuit.

Techniques for sequentially transferring data from a memory device through a parallel interface

A memory array configured to operate as a shift register includes a first column of memory cells with an input and an output and at least a second column of memory cells with an input and an output. The memory array also includes a multiplexer that is connected between the output of the first column of memory cells and the input of the second column of memory cells. The memory array can be operated as a shift register by shifting data from the first column of memory cells to the second column of memory cells through the multiplexer rather than using general routing lines.

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Glendale, CA, United States of America

Yi-Wen Lin