ISSN 1063-7397, Russian Microelectronics, 2006, Vol. 35, No. 4, pp. 243–261. © Pleiades Publishing, Inc., 2006.
Original Russian Text © A.S. Korotkov, 2006, published in Mikroelektronika, 2006, Vol. 35, No. 4, pp. 285–305.
The future of wireless-receiver theory and applica-
tions—and of radio engineering as a whole—is being
shaped by the spread of microelectronic processes, the
advancement of digital signal processing (DSP), and
the modernization of electronic components. The
explosion in sales of communications systems is
another driver of wireless technology.
Nowadays, direct conversion is a dominant technique
of reception in major ﬁelds of digital wireless communi-
cation such as wireless local-area networks (WLANs),
Bluetooth, and DECT. Unlike its superheterodyne prede-
cessor, the direct-conversion receiver uses a low or even
zero intermediate frequency (IF); as a result, a lowpass
ﬁlter (LPF) rather than a bandpass ﬁlter is employed for
channel selection with desired selectivity, in conjunction
with quadrature demodulation. This feature represents a
signiﬁcant advantage because an LPF is easily integrated
with the rest of a receiver. As a consequence, modern
mobile receivers usually have their analog and digital
portions placed on one full-custom chip, a further step
toward the implementation of the system-on-a-chip con-
cept. By contrast, bandpass ﬁlters with comparatively
high center frequency and suitable selectivity are still
realized as a bulky and costly off-chip component, sur-
face-acoustic-wave ﬁlters being an example.
This paper presents a review of integrated receivers
realized in complementary metal–oxide–semiconductor
(CMOS) technology, which indeed predominates in digital
and mixed-signal circuits. It is concerned with the receiver
, which consists of a low-noise ampliﬁer (LNA), a
local oscillator (LO), mixers, ﬁlters, and analog-to-digital
converters (ADCs). Note also that the design concepts and
performance data of channel-select LPFs and high-resolu-
-modulation ADCs are given in [1–4].
ingly, our focus is on LNAs, LOs, and mixers.
The review is organized as follows. Section 2 is con-
cerned with the principles and implementation prob-
lems of zero-IF receivers. Section 3 discusses
approaches to the circuit realization of building blocks
for zero-IF front ends. Section 4 deals with low-IF
receivers. Section 5 outlines alternatives to CMOS.
Section 6 presents main conclusions.
There is no doubt that each of the building blocks
merits a separate review. Our aim here is merely to out-
line general trends in the theory and implementation of
integrated receivers and to help the reader assess the
overall standard achieved by the technology.
2. PRINCIPLES AND IMPLEMENTATION
PROBLEMS OF ZERO-IF RECEIVERS
Although the concept of zero-IF reception was ﬁrst
formulated as early as in 1924, it was not until 1947 that
it was put into practice, the ﬁrst application being mea-
surements in telephony . Its main advantages are the
(i) The problem of image rejection is overcome, so
that the receiver preselection portion is simpliﬁed.
(ii) The fact that most signal processing is done at low
frequencies implies using LPFs as channel-select ﬁlters;
commonly based on transconductance ampliﬁers, they are
fully compatible with well-established CMOS technology.
Figure 1 shows a simpliﬁed block diagram of the
zero-IF receiver. It includes an antenna interface, an
LNA, an LO, mixers, low-frequency ampliﬁers (LFAs)
with controllable gain, channel-select LPFs, ADCs, and
a DSP unit. The LO is realized as a voltage-controlled
See also the special issues
IEE Proc.—Circuits Devices Syst.
IEEE Trans. Circuits Syst.—II
, Oct. 2003; and
Trans. Circuits Syst.—I
, Jan. 2004.
Integrated Receivers for Wireless Communications: A Review
A. S. Korotkov
St. Petersburg State Technical University, St. Petersburg, Russia
Received June 15, 2005
—A review is presented that addresses the circuit-design aspects of integrated receiver front ends with
their CMOS realization in mind. Performance data on speciﬁc front ends and their individual units are given
with emphasis on low-noise ampliﬁers, mixers, and voltage-controlled local oscillators. Promising lines of
research and development are identiﬁed.