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US 7,124,161 B2Granted
Apparatus and method for implementing efficient arithmetic circuits in programmable logic devices
AssigneeAltera Corporation
InventorsChang Choo, Asher Hazanchuk
Life of this patent
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Abstract
Efficient implementation of arithmetic circuits in programmable logic devices by using Look-Up Tables (LUTs) to store pre-calculated values. A table look-up operation is performed in place of complex arithmetic operations. In this way, at the expense of a few LUTs, many logic elements can be saved. This approach is particularly applicable to circuits for calculating reciprocal values and circuits for performing normalized LMS algorithm.
Claims10
A circuit for calculating reciprocal values, comprising:
- an input for receiving input data, the input data being partitionable into a plurality of segments including a first segment and a second segment;
- a first look-up table coupled to the input, the first look-up table having stored therein first pre-calculated values, the first look-up table configured to receive the first segment and for providing a first respective one of the first pre-calculated values in response to the first segment;
- a first shifter circuit coupled to the first look-up table, the first shifter circuit configured to receive the first respective one of the first pre-calculated values and for generating a first shifted value by shifting the first respective one of the first pre-calculated values according to a relative position of the first segment within the input data;
- a second look-up table coupled to the input, the second look-up table having stored therein second pre-calculated values, the second look-up table configured to receive the second segment and for providing a second respective one of the second pre-calculated values in response to the second segment;
- a second shifter circuit coupled to the second look-up table, the second shifter circuit configured to receive the second respective one of the second pre-calculated values and for generating a second shifted value by shifting the second respective one of the second pre-calculated values according to a relative position of the second segment within the input data;
- and
- an output selector circuit for selecting one of the first shifted value and the second shifted value as an approximate reciprocal value of the input data.
4 more elements
Dependencies are inferred from the claim text.