An FCC compliant pulse generator for IR-UWB communications

In [1], we have shown that it is feasible to design filters with arbitrary waveform responses and therefore we propose an ultra-wideband pulse generator incorporating a filter with a Daubechies' impulse response (i.e. maximally flat over the desired frequency range). This pulse generator is co-designed with wideband antennas. An eight-order Pade approximation of its transfer function is selected to implement the FCC stipulated frequency spectrum. Subsequently, the orthonormal [2] form is adopted, which is intrinsically semi-optimized for dynamic range, has low sensitivity to component mismatch, high sparsity and whose coefficients can be physically implemented. Each coefficient in the state-space description of the orthonormal ladder filter is implemented at circuit level using a novel 2-stage gm cell employing negative feedback. Simulation results in IBM's CMOS 0.13 mu m technology show that this pulse generator requires a total current of 25mA from a 1.2V power supply. The frequency coverage of the simulated waveform is about 85%, of the FCC mask.