An Energy-Efficient All-Digital UWB Transmitter Employing Dual Capacitively-Coupled Pulse-Shaping Drivers

Abstract

This paper presents an all-digital, non-coherent, pulsed-UWB transmitter. By exploiting relaxed center frequency tolerances in non-coherent wideband communication, the transmitter synthesizes UWB pulses from an energy-efficient, single-ended digital ring oscillator. Dual capacitively coupled digital power amplifiers (PAs) are used in tandem to attenuate low frequency content typically associated with single-ended digital circuits driving single-ended antennas. Furthermore, four level digital pulse shaping is employed to attenuate RF sidelobes, resulting in FCC compliant operation in the 3.5, 4.0, and 4.5 GHz IEEE 802.15.4a bands without the use of any off-chip filters or large passive components. The transmitter is fabricated in a 90 nm CMOS process and occupies a core area of 0.07 mm 2. The entirely digital architecture consumes zero static bias current, resulting in an energy efficiency of 17.5 pJ/pulse at data rates up to 15.6 Mb/s.

Low Power Impulse Radio Transceivers

“…Pulse-shaping is also important for better inter-band isolation and side-lobe rejection as well as improved spectral efficiency. Thus, low power pulse-shaping techniques that avoid the use of external filters or baluns is an active area of research [12].…”

“…The two disadvantages usually associated with ring-oscillators of phase-noise and process variability are not of great concern here as most UWB-IR receivers are designed for wide-bandwidth and utilize non-coherent energy detection [14] with 4-5 % frequency tolerance. Low variation methodologies [15] or other calibration circuits [12] can also be utilized for variation robustness.…”

“…The design consumes power only when a pulse arrives at the input. Compared to other complex analog [17] or complex digital pulseapproximation techniques [12,18] this design is extremely simple and low power.…”

“…Comparison is done along the line of dynamic power, leakage power, and output voltage swing. In some of the designs the leak- age power is obscured by operating in burst mode, thereby having a high effective pulse rate [12,19,20]. While comparing such designs we have taken care to use equivalent pulse rates.…”

A Scalable, 2.9 mW, 1 Mb/s e-Textiles Body Area Network Transceiver With Remotely-Powered Nodes and Bi-Directional Data Communication

“…Wireless communication devices forming a BAN typically operate in the unlicensed bands, and have to contend with the high losses in those bands in the operating environment [5], [6]. Another scheme for communication with the local base station is the use of body-coupled communication (BCC) [7]- [9].…”