Progress In Electromagnetics Research Symposium, Hangzhou, China, March 24-28, 2008
Frequency Synthesizer Architecture Design for DRM and
and Zhigong Wang
— Based on the speciﬁcations of DRM/DAB receivers, 4 synthesizer structures were
designed for the receiver which supports several radio standards including AM, DRM, FM, and
DAB. Comparisons of the characteristics of the four structures were given. Analysis and calcu-
lations prove that the synthesizer structure 1 with a single VCO and a single loop ﬁlter is the
most suitable one to be used in the DRM/DAB receivers with good performance in phase noise,
reference spurs and lock time, at expense of little more power consumption.
A DRM/DAB receiver will need to support several radio standards including AM, DRM, FM, and
DAB, and needs to provide the necessary ﬂexibility for seamless receive. A key challenge in the full
integration of such a DRM/DAB receiver is the design and implementation of its beating heart,
i.e., the reconﬁgurable frequency synthesizer which acts as the local oscillator (LO) and covers
all the frequency bands of the considered standards. This is due to the diﬃculty in meeting the
performance requirements with on-chip components because of the diverse standards it needs to
support. It is also due to the simulation of the synthesizer, a task that requires mixed-signal tools
that should provide radio frequency, analog, and digital perspectives.
We have proved that a double-conversion low-IF structure is the most suitable architecture for
the DRM/DAB receiver, and the ﬁrst intermediate frequency (
) is 36.95MHz and
for DAB, 175kHz for other bands in this system. The receiver needs two quadrature LO signals,
the ﬁrst one is generated by a synthesizer and the second one is a ﬁxed frequency, which is easy to
be generated. So, only the synthesizer which generates the ﬁrst quadrature LO is discussed in this
2. DESIGN SPECIFICATIONS
Some of the main design speciﬁcations and considerations are given as follows.
2.1. Output Frequency Range and Resolution
The output frequency range and resolution of the frequency synthesizer are listed in Table 1.
Table 1: The output frequency range and resolution.
Output frequency range (MHz)
2.2. Phase Noise and Spurious Frequencies
Numerical stipulation of phase noise for this design, a typical value of
80dBc/Hz @1kHz is chosen.
Generally speaking, all sidebands need to be approximately 70 to 80dB below the main carrier.