Reconfigurable Architecture of a Fully Digital Transmitter with Carrier-Frequency Pulse-Width Modulation

A kind of fully digital transmitter architecture with high ability for reconfiguration is proposed. It utilizes polar coordinate conversion technique, which transforms the baseband I, Q signals into the amplitude and phase, and then handles the amplitude and phase separately. The amplitude is quantified via the method of digital lookup table and different quantization values select different time-delays for a certain IF square wave. These delayed square waves and the reference square waves generate different pulse-widths signal by an XOR gate. The phase is quantified in the same way, selecting different delays of carrier clock by the quantization values. Therefore, the rising edges of the RF carrier present the phase information. Finally, adding the pulse width modulated signal to radio frequency carrier wave, the baseband information is converted to the RF information, with the density of RF pulse presenting amplitude information. The circuit-level simulation results verify that the proposed architecture of the transmitter achieves reconfigurable CF and 20 dB spectrum optimization, when compared with the existing intermediate-frequency PWM based designs.