A bit serial LDI recursive digital filter

The practical implementation of a bit serial lossless discrete integrator (LDI)[1] recursive ladder filter suitable for implementation as a single integrated circuit is described. The low coefficient sensitivity and simplicity of the LDI signal flowgraph make the filter structure suitable for implementing high quality digital filters. A bit serial integrated circuit filter has been designed and simulated using the silicon compiler system FIRST[2,3]. The LDI filter coefficients which yield a Chebyscheff transfer function characteristic are found using an exact synthesis method[4]. The finite precision time domain response of the filter is simulated using the FIRST simulator and the magnitude response is verified by calculating the fourier transform of the filter unit sample response. The LDI filter implementation makes use of an alternate clocking scheme which simplifies the signal flow graph. This is a form of multiplexing which is easily implemented using bit serial arithmetic.