20-10-2012, 02:02 PM
A Highly-Integrated 3–8 GHz Ultra-Wideband RF Transmitter With Digital-Assisted Carrier Leakage Calibration and Automatic Transmit Power Control
A Highly-Integrated 3–8 GHz Ultra-Wideband.pdf (Size: 1.36 MB / Downloads: 38)
INTRODUCTION
F EDERAL COMMUNICATIONS COMMISSION (FCC)
approved the ultra-wideband (UWB) standard for commercialization
in February 2002. To avoid interfering the
existing narrowband communication systems, the transmit
power spectral density level is limited to 41.3 dBm/MHz
[1]. Low transmit power leads UWB to be suitable for wireless
personal area network (WPAN) applications. One of the
UWB systems is the multi-band (MB)-OFDM UWB which,
proposed by WiMedia/MBOA alliance, divides the frequency
spectrum of 3.1–10.6 GHz into five band groups [2]. Band
group 1 (3.2–4.7 GHz) has the first priority, while the others
are reserved for further usage. But the frequency spectrum of
Band group 1 overlaps with that ofWiMax, which was recently
proposed for wireless metropolitan area network (WMAN)
applications.
ARCHITECTURE AND SPECIFICATIONS
The architecture of the proposed transmitter is as shown in
Fig. 1, which carries out the direct-conversion architecture, including
an analog baseband (PGAs and filter) and a RF up-converter.
The analog baseband featured wide bandwidth of 250
MHz is consisted of a 6th-order Chebyshev low-pass filter and
baseband PGAs. The RF up-converter designed to cover from 3
to 8 GHz is composed by an IQ modulator, a RF VGA, a differential-
to-single-ended (D-to-S) amplifier and a power amplifier
(PA). An automatic transmit power control (ATPC) is consisted
of a TSSI, the RF VGA, a off-chip analog-to-digital converter
(ADC), a off-chip digital-to-analog converter (DAC), and a digital
counter.
EXPERIMENTAL RESULT
The UWB RF transmitter is implemented in a 1.2 V 0.13- m
CMOS process. The photograph of the chip is as shown in
Fig. 15. The RF circuits and the analog baseband occupy
an active area of mm and mm , respectively.
The following measurement results are based on
the bias condition of current consumption of 55 mA from a
1.2 V supply. Fig. 16 shows the measured frequency response
of the analog baseband with bandwidth of 250 MHz.