Johnna Powell

System design considerations for ultra-wideband communication

This article discusses issues associated with high-data-rate pulsed ultra-wideband system design, including the baseband processing, transmitter, antenna, receiver, and analog-to-digital conversion. A modular platform is presented that can be used for developing system specifications and prototyping designs. This prototype modulates data with binary phase shift keyed pulses, communicates over a wireless link using UWB antennas and a wideband direct conversion front-end, and samples the received signal for demodulation. Design considerations are introduced for a custom chipset that operates in the 3.1-10.6 GHz band. The chipset is being designed using the results from the discrete prototype.

Differential and single ended elliptical antennas for 3.1-10.6 GHz ultra wideband communication

The paper introduces differential and single ended antenna designs for ultra wideband 3.1-10.6 GHz communication. The primary design is an ultra thin, low profile differential antenna with an incorporated ground plane for use with a UWB IC receiver. The differential capability eases the design complexity of the RF front-end, and the incorporation of a ground plane enables conformability with small electronic UWB devices. Two single ended designs are also presented for use with a UWB IC transmitter. Both designs result in excellent bandwidth, efficiency, and nearly omnidirectional radiation patterns. Viability of these antennas is tested with a UWB pulse transmitter. Time domain responses are compared to that of a commercial 1-18 GHz double ridged waveguide horn.

SiGe Receiver Front Ends for Millimeter-Wave Passive Imaging

A wideband 77-GHz front-end receiver for passive imaging has been designed and characterized. This system comprises a fully differential low-noise amplifier (LNA), double-balanced mixer, and voltage-controlled oscillator (VCO). The 77-GHz LNA achieves 4.9-6.0-dB noise figure (NF), 18-26-dB gain, and S11 and S22 of - 13.0 and - 12.8 dB, respectively. The double-balanced mixer achieves 12-14-dB NF, 20-26-dB conversion gain, and -26-dBm P1dB (input referred). The VCO achieves output power from - 2 to 0 dBm with phase noise of ~ -93 dBc/Hz at 72 GHz, and can be tuned by approximately 3 GHz. The NF can be substantially improved with the addition of image-reject Chebyshev bandpass filters at the interface between the LNA and mixer. The 77-GHz receiver achieves 40-46-dB max conversion gain, output-referred P1dB of 2 dBm, and power dissipation of 195 mW. A 90-GHz LNA has also been characterized as an integral part of a higher resolution 94-GHz imager. This LNA achieves 22-dB maximum gain, 7.0-dB NF, and - 25- and - 10-dB S11 and S22 , respectively, at 90 GHz. This LNA also exhibits excellent ultra-wideband performance, achieving ges 10-dB gain from 40 to 100 GHz.

Digital architecture for an ultra-wideband radio receiver

The 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. The paper shows how probability of error and the bit resolution of the ADC can be scaled depending on the signal-to-noise ratio (SNR), signal-to-interference ratio (SIR), and the type of UWB signal. It also includes considerations on timing recovery for pulsed UWB.

A 77-GHz Receiver Front End for Passive Imaging

A Wideband 77-GHz Front End Receiver for Passive Imaging has been designed and characterized. This system comprises a fully differential LNA, double-balanced mixer and VCO. The LNA achieves 4.9-6.0 dB NF, 18-26 dB gain, and S11, S22 of -13.0 and -12.8 dB, respectively. The double-balanced mixer achieves 12-14 dB NF, 20-26 dB conversion gain and -26 dBm PldB (input-referred). The VCO achieves output power from -2 to 0 tlBm with phase noise of ~-93 dBc/Hz at 72 GHz, and approximately 3 GHz of tuning range. The receiver achieves 40-46 dB max conversion gain, output-referred P1dB of 2 dBm and power dissipation of 195 mW.

77 and 94-GHz Downconversion Mixers in SiGe BiCMOS

Double-conversion superheterodyne downconverter blocks operating around 77 GHz and 94 GHz have been realized in 0.13-mum SiGe BiCMOS technology. Both use a single-balanced RF mixer to downconvert the signal to an 8.8 GHz IF, which is amplified and downconverted a second time to baseband. The 77-GHz circuit achieves an upper SSB NF of 12.8 dB at 77 GHz and <12 dB at 76 GHz, with 20 dB of conversion gain and an input-referred 1-dB compression point of -14.7 dBm. The 94-GHz circuit achieves an upper SSB NF of 17.2 dB at 94 GHz, with 15 dB of conversion gain and an input-referred 1-dB compression point of -10.7 dBm. Both circuits use a bias current of 3.2 mA in the RF mixer core, with total testsite power consumption of 120 mA from a 3-V supply.

Direct Conversion Pulsed UWB Transceiver Architecture

Ultra-wideband (UWB) communication is an emerging wireless technology that promises high data rates over short distances and precise locationing. The large available bandwidth and the constraint of a maximum power spectral density drives a unique set of system challenges. This paper addresses these challenges using two UWB transceivers and a discrete prototype platform.

A 3.1 to 10.6 GHz 100 Mb/s Pulse-Based Ultra-Wideband Radio Receiver Chipset

A complete 3.1-10.6 GHz ultra-wide band receiver using 500 MHz-wide sub-banded binary phase shift keyed (BPSK) pulses has been specified, designed and integrated as a three chip and planar antenna solution. The system includes a custom designed 3.1-10.6 GHz planar antenna, direct-conversion RF front-end, 500 MS/s analog to digital converters, and a parallelized digital back-end for signal detection and demodulation. A 100 Mb/s wireless link has been established with this chipset. A bit-error-rate (BER) of 10-3 was recorded at -80 dBm at a rate of 100 Mb/s for properly acquired packets in the lowest frequency band. Bit-scaling of the ADC from 1 to 5 bits reveals a 4 dB improvement in the link budget

Pulse-Based, 100 Mbps UWB Transceiver

A pulse-based FCC-compliant ultra-wideband (UWB) transceiver is designed and integrated as a four chip and planar antenna solution. The signaling is based on 500 MHz-wide subbanded binary-phase-shift-keyed (BPSK) Gaussian pulses centered in one of 14 bands across the 3.1–10.6 GHz bandwidth. The system includes a UWB planar antenna, a Gaussian BPSK transmitter, a direct-conversion front-end, dual 500 MSps analog-to-digital converters, and a parallelized digital baseband for timing control and data demodulation. The RF local oscillators and baseband gain stages are implemented externally. A 100 Mbps wireless link is established with this chipset. A bit-error rate of 10-3 is observed at a -84 dBm sensitivity. This energy-aware receiver is implemented with strategic hardware hooks such that the quality of service is exchangeable with power consumption.