This paper proposes a capable constant multiplier architecture with the help of an architecture called Binary Common Sub-Expression (BCSE)algorithm. As multiplication using coefficients or constants plays a necessary role in digital signal processing(DSP). Firstly, a single constant multiplier switching between some constants are converted to an n-bit constant multiplier in which any of the bit can be generated at the output according to the input bit x using the BCSE algorithm. Then an RRC filter is designed using the n-bit multiplier and finally, the performance of the RRC filter is compared with that of FIR filter.