Benefits of Superconductor Digital-rf Transceiver Technology to Future Wireless Systems

Ultrafast superconductor digital microelectronic circuits operate at speeds up to 100 GHz, enabling true digital-RF architecture. This permits direct conversion between analog RF and digital baseband signals, replacing frequency and protocol-specific analog hardware with flexible, software-programmable digital processors. On the receive side, high sampling-speed (20 Gsamples/s) and linearity (>100 dB spur-free dynamic range) of superconductor analog-to-digital converters (ADCs), digital down-converters and ultrafast (20 GHz) digital filters have already been demonstrated by HYPRES. This will enable broadband digitization of the incoming RF waveform directly, leading to true digital channelization under full software control. In addition, the lower receiver noise temperature enhances information capacity, even in interference-limited systems. Similarly, on the transmit side, a high sampling-speed and quantum-linear digital-toanalog converter (DAC) preceded by digital up-converters and digital filters provide the scheme for direct synthesis of a spectrally pure RF transmit waveform. Furthermore, the power of digital processing at RF allows direct digital predistortion of the transmit waveform for linearization of the entire power amplifier chain. In this paper, we will discuss the benefits to future wireless systems, in terms of expanded range of high-data-rate coverage, lower handset battery power, higher spectral efficiency and lower cost for multi-carrier base-stations.