Design Considerations of the Interpolative Digital Transmitter for Quantization Noise and Replicas Rejection

The digital transmitter (DTX) offers both high power efficiency and frequency flexibility by merging signal amplification and modulation in the switching power amplifier. Yet, the back-end high-speed digital baseband interface is challenging and bulky for obtaining low out-of-band noise. This brief provides an analytical study of the DTX linear interpolation technique, which can be easily utilized for optimizing the replica rejection and noise-filtering capabilities of the DTX.