Scaling accumulator mult (signed value) in Distributed Arithmetic

[MariuszK]

Hello,
I am going write distributed arithmetic unit for signed values.
Currently I have problem with scaling accumulator multiplier for
signed values (negative positive).

I use sign extending to input and table values to perform scaling
accumulation.
That's works but ... this is inefficient all additions must be double-
precision and at least twice as many partial products are needed.

Is it possibility to implement Scaling Accumulator Multipliers (for
signed values) more efficient? (without sign extending)

Regards,
Mariusz