Photonic generation of background-free millimeter-wave
ultra-wideband signals
(Invited Paper)
Wei Li (李 伟)
1,2
, Ming Li (李 明)
1,2
, and Ninghua Zhu (祝宁华)
1,2,
*
1
State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences,
Beijing 100083, China
2
University of Chinese Academy of Sciences, Beijing 100049, China
*Corresponding author: nhzhu@semi.ac.cn
Received September 14, 2016; accepted December 6, 2016; posted online January 10, 2017
We review the recent progress of photonic generation of millimeter wave (MMW)-ultra-wideband (UWB) sig-
nals. To fully satisfy the standard defined by the Federal Communications Commission (FCC), the baseband
signal (background signal) and the residual local oscillator (LO) signal should be well controlled. We discuss
several schemes in this work for generating background-free MMW-UWB signals that are fully
compliant with the FCC requirement.
OCIS codes: 060.5625, 070.1170, 060.2310.
doi: 10.3788/COL201715.010007.
Benefiting from low power consumption, immunity to
multipath fading, carrier free, and high data rate, ultra-
wideband (UWB) has attracted more and more attention
for short-range high-capacity wireless communication and
sensor networks
[1]
. The Federal Communicati ons Commis-
sion (FCC) defined the UWB signal as a radio frequency
(RF) signal that occupies a spectral bandwidth of more
than 500 MHz or more than 20% fractional bandwidth
with a power density no more than −41.3 dBm∕MHz
[2]
.
Up to now, various approaches have been proposed to gen-
erate UWB signals in the centimeter-wave (CMW) band
(3.1 to 10.6 GHz) for indoor communications
[3–7]
and in the
millimeter-wave (MMW) band (22 to 29 GHz) for outdoor
communications
[8–19]
.
In this Review, we review recent progress on the pho-
tonic generation of UWB signals in the MMW band with
emphasis on the generation of background-free and FCC
compliant MMW-UWB pulses.
The electrical spectrum of MMW-UWB signals for
outdoor communications spreads from 22 to 29 GHz.
Generally, it can be realized by frequency upconversion
of a baseband signal to the local oscillator (LO) band since
an electrical mixer can cover this frequency range easily.
Actually, the electrical mixer-based approach is more ma-
ture and easily available for us. Thus, we will first check
the possibility of the electrical mixer-based approach for
the generation of MMW-UWB signals.
The mixer available in our lab has an intermediate fre-
quency (IF) bandwidth from dc to 8 GHz, an LO band-
width from 14 to 26 GHz, and an RF bandwidth from
14 to 26 GHz. Due to the limited bandwidth of the mixer,
we tried to upconvert the baseband signal to the LO band
from 19 to 26 GHz that is 3 GHz lower than the FCC
standard. The baseband signal has a 10 dB bandwidth
of 7 GHz, while the frequency of the LO signal is 22.5 GHz.
The electrical spectrum of the upconverted signal is
shown in Fig.
1(a). The baseban d signal is successfully up-
converted to the LO band. The generated MMW-UWB
signal generally follows the FCC mask. Unfortunately, a
strong LO signal can be obviously observed that is 26 dB
higher than the upconverted signal. This is attributed to
the poor isolation of the mixer. The corresponding wave-
form is shown in Fig.
1(b). The residual LO signal gener-
ates a strong sinusoidal microwave signal at both sides of
the UWB waveform. The strong LO signal is hard to be
eliminated using a notch filter. The power of the generated
MMW-UWB signal has to be attenuated by 26 dB to
Fig. 1. Measured (a) electrical spectrum and (b) waveform of the
upconverted UWB signal using an electrical mixer.
COL 15(1), 010007(2017) CHINESE OPTICS LETTERS January 10, 2017
1671-7694/2017/010007(5) 010007-1 © 2017 Chinese Optics Letters