Fred S. Lee

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In the past few years, wireless microsensor networks have attracted a great deal of attention in the research community. This is due to the applications that will be enabled once wireless microsensor networks are in place. The design of wireless microsensor networks, however, represents a difficult challenge. Since many applications require fault-tolerant,(More)
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Pulsed ultrawide band provides the energy needed for a high data-rate(More)
This paper presents a baseband processor for pulsed ultra-wideband signals. It consists of an analog to digital converter (ADC), a clock generation system and a digital back-end. The FLASH interleaved ADC provides four bit samples at 1.2GSPS. The back-end uses parallelization to process these samples and to reduce the signal acquisition time to 70µs. The(More)
— A custom UWB transceiver chipset is presented that communicates in three 550MHz-wide channels in the 3.1 to 5GHz band by using pulse position modulation (PPM). The transmitter uses an all-digital architecture and calibration technique to synthesize pulses with programmable width and center frequency. No analog bias currents or RF oscillators are required(More)
— This paper presents analysis of a digital Ultra-wideband (UWB) radio receiver operating in the 3.1 GHz to 10.6 GHz band. Analog to digital converter (ADC) bit precision is analyzed on two types of UWB signals-OFDM UWB and pulsed UWB-all in the presence of Additive White Gaussian Noise (AWGN) and a narrowband interferer in the channel. This paper shows how(More)
— A 900MHz bandwidth front-end with a-100dB/decade roll-off for a baseband pulse-based BPSK ultra-wideband transceiver is designed and tested in 1.8V 0.18µm CMOS. Trade-offs in noise figure (NF) and voltage gain within broadband power-matched and unmatched (voltage-boosted) conditions of the front-end are discussed. The front-end achieves 38dB of gain and(More)