Novel FFT LSI for orthogonal frequency division multiplexing using currentmode circuit

We propose a design method of fast Fourier transform (FFT) large-scaled int egration (LSI) for an orthogonal frequency division multiplexing (OFDM) Sys tem. The proposed FFT LSI is designed with simple current mode circuits, wi red-OR connection and, gate-width-ratioed current mirror. For a low power c onsumption, two design methods are proposed, current-cut (CC) and rounding process. The CC operation is performed with on-off operation of a current s ource. The rounding process is adopted for the component of the FFT matrix. Bit error rate (BER) in the OFDM system is simulated from "0.1" rounding s tep to "1.0". The BER performance of the FFT matrix with the "0.2" rounding step has little degradation from that of the original FFT matrix. The 8-po int FFT LSI with the "0.2" rounding step is designed and implemented using a 0.8 mum complementary metal-oxide semiconductor (CMOS) technology. On the basis of measurement of the 8-point FFT LSI, the power consumption of the 64-point FFT LSI using CC can be estimated as being less than 10 mW.