Low-voltage FIR filter for receivers used in communication systems

The paper presents the principle and a possible implementation for an improved finite-impulse response (FIR) filter intended to be used with receivers operating in low voltage supply conditions. Basically, the main application of this filter is in the equalizer building block of a wireless receiver. To provide the filter with simple programmability through digital words, current dividers based on MOS transistors are included in its structure. Also, a very important block of the presented filter includes sample/hold circuits that must work at the same low supply voltage as the entire system. Low voltage operation of the proposed filter is achieved using the switched current technique.