In this paper, we introduce a novel differential signaling approach for ultra-wideband (UWB) communications using multiple digital carriers. Unlike the transmitted reference (TR), differential and noncoherent UWB that also bypass explicit channel estimation, our scheme avoids the analog delay element whose on-chip implementation is challenging. Compared with the frequency-shifted reference (FSR) UWB, our multi-carrier differential signaling captures the signal energy more effectively and can achieve the full diversity gain, even in the presence of inter-frame interference. In addition, our approach relies on digital carriers that do not incur any spectrum expansion and can be realized with standard discrete-cosine transform (DCT) or fast fourier transform (FFT) circuits operating at the frame-rate. Simulations are also carried out to corroborate our theoretical analysis.