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Altera_Forum
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14 years ago

NCO help...

Hi i'm trying to test a fixed point filter on a FPGA board, my filter has an input of 16 bit, but the maximum value it can take without saturation is 1023 which is 11 bits. so far the only signal i'v...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

If you have say A = 8 bits signed and you connect it to B = 12 bits signed then you connect 8 LSBs of A to 8 LSBs of B.

But the remaining 4 MSBs of B must not be zeroed, but must follow sign bit of A.

e.g. 0000 1111 = + 15 on 8 bits

0000 0000 1111 = +15 on 12 bits

1111 0001 = - 15 on 8 bits

1111 1111 0001 = -15 on 12 bits

Hope it is clear.