IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS–I: REGULAR PAPERS, VOL. 64, NO. 3, MARCH 2017
731
High-Efficiency Broadband Rectifier With Wide
Ranges of Input Power and Output Load
Based on Branch-Line Coupler
Xiu Yin Zhang, Senior Member, IEEE, Zhi-Xia Du, and Quan Xue, Fellow, IEEE
Abstract— In this work, a novel rectifier based on a branch-line
coupler is proposed to operate within wide ranges of input power,
operating frequency and output load. In the proposed topology,
two output ports of the coupler are connected with two identical
sub-rectifiers and the isolation port is directly connected to the
ground. The input impedance of the two sub-rectifiers varies
with different input power, operating frequency and output load,
which leads to impedance mismatching. By using the branch-line
coupler with grounded isolation port, the power reflected from
the two sub-rectifiers can be partially re-injected back to the
sub-rectifiers. Thus, the power can be reused and the RF-dc
conversion efficiency can be improved. Theoretical analysis and
performance comparison are carried out. The results indicate
that the proposed topology is able to realize high efficiency
with wide input power, frequency and load dynamic ranges.
For validation, a rectifier working at 2.45 GHz is designed.
The fabricated rectifier circuit demonstrates a maximum RF-dc
conversion efficiency of 80.8%. The measured efficiency remains
over 70% with the input power from 10 dBm to 18.6 dBm and
the operating frequency from 2.08 to 2.58 GHz.
Index Terms— Branch-line coupler, high efficiency, microwave
power transmission (MPT), rectifier.
I. I NTRODUCTION
M
ICROWAVE power transmission (MPT) is a promising
technology and has potential applications where the
power transmission through wires is inconvenient or impossible, such as wireless sensors. The efficiency of the total MPT
system heavily depends on RF-dc conversion efficiency of the
microwave rectifier. Therefore, the optimal design of a highefficiency microwave rectifier is crucial.
Several types of topologies are employed to realize rectifiers, for instance, diodes in series, diodes in parallel, diodes
in bridge, diodes in voltage doubler, and so on. Moreover, in
order to improve the RF-dc conversion efficiency, different
kinds of topologies [1]–[6] and analytical models [7]–[8]
Manuscript received July 1, 2016; revised September 12, 2016; accepted
September 26, 2016. Date of publication October 31, 2016; date of current
version February 23, 2017. This work was supported in part by the Natural
Science Foundation of China under Grants 61422106 and 61327005, and in
part by the Top-Notch Young Talents Program of China. This paper was
recommended by Associate Editor A. Fayed.
X. Y. Zhang and Z.-X. Du are with the Guangdong Provincial
Key Laboratory of Short-Range Wireless Detection and Communication
(Grant No 2014B030301010), the School of Electronic and Information
Engineering, South China University of Technology, Guangzhou 510641,
China (e-mail: zhangxiuyin@hotmail.com).
Q. Xue is with the State Key Laboratory of millimeter Waves, Department
of Electronic Engineering, and CityU Shenzhen Research Institute, City
University of Hong Kong, Hong Kong, China.
Color versions of one or more of the figures in this paper are available
online at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/TCSI.2016.2614331
have been proposed. These rectifiers are usually optimized
for specific operating conditions, including input power level,
operating frequency, and fixed output load. However, the
available electromagnetic energy is generally not constant. The
variation of input power and operating frequency lead to input
impedance variation since the rectifying device is nonlinear.
This degrades rectifier performance due to the impedance
mismatch. Moreover, the rectifier output needs to be connected
to various loads, such as dc-dc converter or regulator circuits.
The load variation also leads to input impedance change and
thus results in degraded efficiency [9].
To reduce the sensitivity of rectifying efficiency to input
power and output load variations, resistance compression networks (RCNs) are introduced [9]–[12]. The input impedance
variation range is reduced by the RCNs. However, the frequency bandwidth of RCNs is limited. In [13], an improved
RF–dc converter based on a class-E rectifier is presented with
wide-dynamic-range input matching and the peak efficiency is
60% for an input power of 17 dBm at 800 MHz. In [14], a
2.4 GHz adaptive rectifier with extended input power range is
presented using extra control circuit. The device is fabricated
on CMOS technology, with peak efficiency being 47%. In [15],
two sub-rectifying circuits working at different input power
levels are combined by a 2:1 power divider. There are two peak
power conversion efficiencies and thus the input power range
corresponding to high efficiency can be extended. Moreover,
a GaAs pHEMT is adopted to keep the voltage on diode
constant when it reaches the diode breakdown voltage, which
can extend operating power range [16]. Besides, a rectifier
using maximum power point tracking method can maintain
high efficiency for a wide load range [17]. Several broadband
and multiband rectifiers are also designed by constructing
wideband matching network [18]–[21]. For example, a broadband rectifier is designed by maximizing the quality factor
of the matching network [19]. However, these works focus
on extending the RF input power range [9]–[16], dc load
range [17] or operating frequency bandwidth [18]–[20]. None
of them can simultaneously extend the ranges of input power,
output load and operating frequency.
In this paper, a novel rectifier based on a branch-line
coupler is proposed to operate within wide ranges of input
power, operating frequency and output load. The proposed
rectifier consists of two sub-rectifying circuits and a branchline coupler with grounded isolation port. With the change
of the input power and output load as well as operating
frequency, the input impedance of the sub-rectifiers varies,
leading to impedance mismatch. The reflected waves from the
1549-8328 © 2016 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission.
See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
Authorized licensed use limited to: Guangdong Univ of Tech. Downloaded on April 12,2023 at 08:24:38 UTC from IEEE Xplore. Restrictions apply.
732
Fig. 1.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS–I: REGULAR PAPERS, VOL. 64, NO. 3, MARCH 2017
Block diagram of the proposed topology.
sub-rectifiers due to mismatching can be partially re-injected
back to the sub-rectifiers by using the coupler. Therefore, the
reflected power can be reused, resulting in improved efficiency.
The proposed rectifier can remain high efficiency for wider
ranges of input power level, operating frequency and output
load. Theoretical analysis is carried out in Section II. The
design of proposed rectifier and the efficiency comparisons
between the rectifiers with and without the coupler are shown
in Section III. For validation, experiment is carried out and
the results are compared with the prior works in Section IV.
Finally, a conclusion is given in Section V.
II. T HEORETICAL A NALYSIS
The proposed rectifier topology is shown in Fig. 1. Two
identical sub-rectifiers are connected to the output ports of
a branch-line coupler. When the input power, operating frequency and output load vary, the input impedances Z in1
and Z in2 of the sub-rectifiers change, resulting in impedance
mismatch. The proposed topology is able to improve matching performance and reduce power loss due to impedance
mismatch.
In order to analyze the operating principle of the proposed
rectifier, the topology is simplified as shown in Fig. 2. The subrectifiers 1 and 2 are replaced by the load with the complex
impedance Z L1 and Z L2 , respectively. Since the sub-rectifiers
are the same, Z L1 is equal to Z L2 . In the analysis, the loss
of the branch-line coupler is ignored. At first, the input wave
a1 transmits to ports 2√and 3 as shown in Fig.
√ 2 (a), thus
we have b2 = −(a1 / 2) j and b3 = −a1 / 2 according
to [22]. Since the output load Z L varies with input power
and impedance
√ mismatch exists,
√ the reflected waves a2 and a3
are - (a1 / 2) j and −a1 / 2, respectively, where is the
reflection coefficient at the corresponding power. The waves
a2 and a3 are transmitted to the coupler and then delivered to
ports 1 and 4 as shown in Fig. 2 (b). The output waves b1 and
b4 can be calculated as
a3
a2
b1 = − √ − √ j = 0
2
2
a2
a3
b4 = − √ − √ j = a1 j.
(1)
2
2
Thus, port 1 remains matched and the reflected power is
transmitted to port 4.
Fig. 2. Schematic diagram of the branch-line coupler with grounded isolation
port and output load variation.
In order to re-inject the output wave b4 back to the coupler
and then to the two sub-rectifiers, port 4 is directly connected
to the ground. The output wave b4 can be totally reflected and
transmitted into the coupler as a4 . Therefore, we have
a4 = −b4 = −a1 j.
(2)
Since the wave a4 injected from port 4 is delivered to ports 2
and 3 as shown in Fig. 2 (c), we can obtain
a4
a1
b2 = − √ = √ j
2
2
a4
a1
b3 = − √ j = − √ .
(3)
2
2
According to Fig. 2 (d), the reflected waves a2 and a3 are then
generated and expressed as
a1
√ j
2
a
1
a3 = b3 = − √
(4)
2
where is the reflection coefficient at the corresponding
power. The waves a2 and a3 are re-injected to the coupler
a2 = b2 =
Authorized licensed use limited to: Guangdong Univ of Tech. Downloaded on April 12,2023 at 08:24:38 UTC from IEEE Xplore. Restrictions apply.
ZHANG et al.: HIGH-EFFICIENCY BROADBAND RECTIFIER WITH WIDE RANGES OF INPUT POWER AND OUTPUT LOAD
733
Using the proposed topology, part of the reflected power can
be transmitted into the two sub-rectifiers. The re-used power is
P = PlossT − PlossC
2
= ||2 (1 − )Pinc
Fig. 3.
Schematic diagram of the rectifier based on (a) the symmetric
T-junction combiner and (b) the branch-line coupler with grounded isolation port.
and the output waves b1 and b4 can be obtained
a
a
b1 = − √3 − √2 j
2
2
a2
a3
b4 = − √ − √ j.
2
2
Combining (4) and (5), we have
(5)
b1 = a1
b4 = 0.
(12)
where the incident power Pinc = |a1 |2 /2. Because of the reused power P, the power injected into the sub-rectifiers of
the rectifiers with the T-junction and the coupler is different.
In the rectifier with the T-junction, since the reflected power
Pref = PlossT = ||2 × Pinc , the power injected to the subrectifiers Pin is equal to (1 − ||2 ) × Pinc , as illustrated
in Fig. 3(a). In the rectifier with the coupler, the power injected
into sub-rectifiers becomes (Pin + P) due to the re-used
power P, as presented in Fig. 3(b). It is noted that the
efficiency of the sub-rectifiers is relative to input power. Here,
we use E M,Pin to represent the efficiency of the sub-rectifiers
at the injected power Pin . The dc output power of the rectifier
with T-junction combiner is (Pin × E M,Pin ) while that of the
rectifier with the coupler is [(Pin +P)×E M,( Pin+P) ]. Thus,
the improved efficiency E(Pinc ) by the proposed method at
the incident power of Pinc can be obtained
(Pin + P) × E M,( Pin +P) − Pin × E M,Pin
Pinc
2 2
= 1 − || E M,( Pin +P)
− 1 − ||2 E M,Pin .
(13)
E (Pinc ) =
(6)
It is seen that the power is delivered to port 1. Since port 1 is
matched, the waves b1 cannot be re-injected to the coupler.
According to (1) and (6), the power loss of the proposed
circuit is
2
2
1
1
PlossC = (|b1 |2 + b1 ) = ||2 |a1 |2 .
(7)
2
2
In order to evaluate the power loss due to impedance
mismatch, the proposed rectifier is compared with the rectifier
without the coupler. An ideal symmetric T-junction combiner
without loss is used instead of the branch-line coupler, as
shown in Fig. 3(a). The electric length of the two symmetric
branches is 90◦ . Z L1 and Z L2 represent the input impedance
of the two identical sub-rectifiers. a1 is the input wave. The
output waves d1 and d2 can be expressed as
a1
◦
d1 = d2 = √ e− j 90 .
(8)
2
Since the output load Z L varies and impedance mismatch is
caused, the reflected waves ar1 and ar2 are
a1
◦
ar1 = ar2 = √ e− j 90 .
(9)
2
The waves ar1 and ar2 are transmitted to the T junction and
then delivered to port 1, thus the power loss can be obtained
as
1
1
1
(10)
PlossT = |ar1 |2 + |ar2 |2 = ||2 |a1 |2 .
2
2
2
Comparing (7) and (10), since | ≤ | ≤ 1, we have
2
1
1
PlossC = ||2 |a1 |2 ≤ ||2 |a1 |2 = PlossT .
(11)
2
2
Therefore, the proposed topology can reduce power loss due to
impedance mismatch of the sub-rectifiers, which is caused by
input power, operating frequency and output load variations.
In this work, we focuses on the operating condition that
the breakdown voltage is not reached. Then, E M,( Pin+P) ≥
E M,Pin . When || = || = 0 or || = || = 1, the efficiency
is not improved. Except the two special cases, we have 0 <
|| < 1, 0 < || < 1 and E M,( Pin+P) > E M,Pin . Thus, (13)
can be simplified as
2 E (Pinc ) > 1 − ||2 − 1 − ||2 E M,Pin
2 = ||2 1 − E M,Pin .
(14)
As can be seen, E(Pinc ) > 0, which indicates that the
conversion efficiency can be improved by using the proposed
topology. The improved efficiency E(Pinc ) depends on the
efficiency E M,Pin and reflection coefficients and of the
sub-rectifiers. Thereby, after the sub-rectifiers are determined,
the efficiency improvement can be quantified.
It is noted that as frequency varies, the magnitude and
phase characteristics of the coupler change gradually, leading
to limited efficiency improvement. Thus, a wideband branchline coupler is beneficial for obtaining high efficiency over
wide frequency band. Thereby, a second-order coupler, which
has wider frequency bandwidth than the first-order one, is
preferred in wideband design. Since the first-order and secondorder couplers exhibit the same magnitude and phase characteristics within the operating band, the above equations can
also be used in the analysis of the rectifier using the secondorder coupler. Based on the above analysis, two proposed
rectifiers with the first-order and second-order couplers are
designed and compared to the rectifier without the coupler, as
addressed in the following section.
Authorized licensed use limited to: Guangdong Univ of Tech. Downloaded on April 12,2023 at 08:24:38 UTC from IEEE Xplore. Restrictions apply.
734
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS–I: REGULAR PAPERS, VOL. 64, NO. 3, MARCH 2017
Fig. 4. Layout of the circuits in the proposed design. (a) Single rectifier;
(b) first-order coupler with grounded isolation port; (c) second-order coupler
with grounded isolation port.
III. D ESIGN OF THE P ROPOSED R ECTIFIER
A. Rectifier Design
To verify the above theoretical analysis, the proposed topology is used in rectifier design with the following procedure.
Note that the proposed method can be applied to various
rectifiers working at different input power, output load and
operating frequencies for practical applications. Here, two prototype rectifiers operating at 2.45 GHz are designed as examples. Firstly, a single rectifier, which is modified from [17], is
designed and optimized for maximum efficiency at 2.45 GHz.
Fig. 4 (a) shows the layout of the modified rectifying structure.
It consists of a matching network, rectifying diodes and dc
pass filter. The matching network transforms the complex
impedance to 50 , and the dc pass filter is designed using harmonic termination. It is noted that we can also use other single
rectifiers in the design. Secondly, a 3 dB branch-line coupler
is designed with grounded isolation port. According to the
analysis in Section II, the frequency bandwidth of the proposed
rectifier is affected by that of the coupler. Therefore, a firstorder coupler and a second-order one are used in the design,
with the layouts shown in Fig. 4 (b) and Fig. 4 (c) respectively.
Finally, two identical single rectifiers are connected to the
output ports of the coupler. In this design, the substrate is
Arlon-AD255, with the thickness of 30 mil, dielectric constant
of 2.55 and loss tangent of 0.0018. It should be noted that
in the following simulation, the capacitor models are from
MURATA and the microstrip line loss is taken into account.
B. Simulated Results and Comparison
At first, the two proposed rectifiers based on the firstorder and second-order couplers are compared with the rectifier without the coupler in terms of the return loss |S11 |.
Fig. 5 shows the return loss |S11 | versus input power, output
load and operating frequency. It can be observed that the two
proposed rectifiers have smaller return loss than the rectifier
without the coupler. Thus the power loss due to impedance
mismatch is reduced by using the proposed method, which
Fig. 5. The return loss |S11 | of the rectifiers with the first-order coupler,
second-order coupler and T-junction versus (a) input power, (b) output load,
and (c) operating frequency.
is also indicated by (11). As illustrated in Fig. 5 (c), the
bandwidth for |S11 | < -20 dB is enhanced from 0.11 GHz to
0.22 GHz by using the proposed method with the first-order
coupler. Moreover, the bandwidth can be further extended to
0.45 GHz by using the second-order coupler, since it has wider
frequency bandwidth than the first-order one.
The RF-dc conversion efficiency versus input power, output
load and operating frequency are shown in Figs. 6–8. The two
proposed rectifiers based on the first-order and second-order
couplers are compared with the rectifier without the coupler.
In the comparison, the losses of the couplers and T-junction
Authorized licensed use limited to: Guangdong Univ of Tech. Downloaded on April 12,2023 at 08:24:38 UTC from IEEE Xplore. Restrictions apply.
ZHANG et al.: HIGH-EFFICIENCY BROADBAND RECTIFIER WITH WIDE RANGES OF INPUT POWER AND OUTPUT LOAD
735
Fig. 6. Performance comparison among the two proposed rectifiers with
the couplers and the rectifier without the coupler versus input power with
RL = 360 at 2.45 GHz.
Fig. 9.
RF-dc conversion efficiency (%) of (a) the proposed rectifier
based on a second-order coupler and (b) the rectifier without the coupler
for RL = 360 .
Fig. 7. Performance comparison among the two proposed rectifiers with the
couplers and the rectifier without the coupler versus output load for an input
power of 17.5 dBm at 2.45 GHz.
Fig. 8. Performance comparison among the two proposed rectifiers with the
couplers and the rectifier without the coupler versus operating frequency with
RL = 360 at 15.5 dBm.
are taken into account, which are around 0.03 dB and 0.01 dB,
respectively. The proposed topology maintains better performance than the rectifier without the coupler. As shown
in Fig. 6, the RF-dc conversion efficiency of the two proposed
rectifiers versus input power remains almost the same. It is
higher than that of the rectifier without the coupler when the
input power varies from 0 dBm to 13 dBm. From 13 dBm to
18 dBm, the efficiencies of the three rectifiers are almost the
same with less than 0.4% difference. This is because the input
impedance of the rectifiers is well matched with the return loss
better than 23 dB and the re-used power P is very small.
As illustrated in Fig. 7, the two proposed rectifiers exhibits
higher efficiency than the one without the coupler when the
output load varies from 50 to 320 . Similarly, within the
output load range of 320 to 390 , the rectifier without
the coupler is still well matched. Thus the efficiencies of the
three ones are almost the same with difference less than 0.3%.
What’s more, Fig. 8 shows that the proposed rectifier based on
a second-order coupler has the widest frequency bandwidth as
compared with the others. Therefore, the second-order coupler
is selected in this design. It should be noted that this work
focuses on the operating condition that the breakdown voltage
is not reached. Otherwise, the power loss in the breakdown
diodes is greatly increased.
Besides, more comprehensive comparison between the proposed rectifier based on a second-order coupler and the
rectifier without the coupler is carried out. Fig. 9 shows the
efficiency versus operating frequency and input power level
for a fixed output load (RL = 360 ). One can observe that
when the input power and operating frequency vary, the RF-dc
conversion efficiency of the proposed rectifier can be maintained over 70% within a larger area than that of the rectifier
Authorized licensed use limited to: Guangdong Univ of Tech. Downloaded on April 12,2023 at 08:24:38 UTC from IEEE Xplore. Restrictions apply.
736
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS–I: REGULAR PAPERS, VOL. 64, NO. 3, MARCH 2017
Fig. 10. RF-dc conversion efficiency (%) of (a) the proposed rectifier based
on a second-order coupler and (b) the rectifier without the coupler for an input
power level of 15.5 dBm.
Fig. 11. RF-dc conversion efficiency (%) of (a) the proposed rectifier based
on a second-order coupler and (b) the rectifier without the coupler at 2.45 GHz.
without the coupler. Moreover, Fig. 10 illustrates the efficiency
versus operating frequency and output load for an input power
level of 15.5 dBm. Furthermore, Fig. 11 presents the efficiency
versus output load and input power level working at 2.45 GHz.
It can be observed from these figures that the proposed rectifier
is able to operate within wider ranges of input power level,
operating frequency and output load in comparison with the
rectifier without the coupler.
Fig. 12.
coupler.
IV. E XPERIMENTAL R ESULTS
For validation, the proposed rectifier with the secondorder coupler is designed and optimized by using electromagnetic (EM) simulation, and then fabricated as shown in Fig. 12.
It consists of two sub-rectifiers and a second-order branchline coupler with grounded isolation port. The parameters are
shown in Fig. 12. The capacitor used in the design is 330 pF,
and the output load RL is 360 .
The fabricated rectifier is characterized in term of RF-dc
conversion efficiency versus input power, operating frequency
and output load. The measurement is carried out by multimeter
and the performance comparison between the rectifier with and
without the coupler is shown in Figs. 13–15. The measured
RF-dc conversion efficiency is obtained by
η(%) =
Pout1 + Pout2
.
Pin
(15)
Photograph of the prototype rectifier based on a second-order
Pout1 and Pout2 are the output power of the two sub-rectifiers,
and Pin is the input power. It is worth noting that the two dc
outputs can be connected in series or in parallel, giving more
choices for output voltage or current.
The EM simulation and measurement RF-dc conversion
efficiencies of the rectifiers with and without the coupler at
15.5 dBm are depicted at Fig. 13. As observed, the greater
than 70% measurement efficiency of the rectifier with the
coupler can be obtained from 2.08 GHz to 2.58 GHz while
that of the rectifier without the coupler is from 2.12 GHz
to 2.49 GHz. There exist slight frequency shift between the
simulated and measured results, which is due to fabrication
tolerance and diode model inaccuracy. It is noted that there are
slight difference between the results in Figs. 13 and 8, which is
Authorized licensed use limited to: Guangdong Univ of Tech. Downloaded on April 12,2023 at 08:24:38 UTC from IEEE Xplore. Restrictions apply.
ZHANG et al.: HIGH-EFFICIENCY BROADBAND RECTIFIER WITH WIDE RANGES OF INPUT POWER AND OUTPUT LOAD
737
TABLE I
C OMPARISON W ITH S OME P RIOR W ORKS W HICH F OCUSED ON E XTENDING I NPUT P OWER R ANGE OR F REQUENCY BANDWIDTH
Fig. 13. EM simulation and measurement efficiencies of the rectifiers with
and without the coupler versus operating frequency for Pin = 15.5 dBm.
Fig. 14. EM simulation and measurement efficiencies of the rectifiers with
and without coupler versus input power.
because they are obtained from EM and schematic simulation.
Fig. 14 shows the EM simulation and measurement efficiencies
versus input power. It can be seen that the maximum measured
Fig. 15. EM simulation and measurement efficiencies of the rectifiers with
and without the coupler versus output load for Pin = 17.5 dBm.
efficiency of the proposed rectifier is 80.8% at 17.2 dBm. The
measured efficiency maintains more than 70% from 10 dBm to
18.6 dBm, and better than 50% from 2.9 dBm to 20.2 dBm.
The input power range corresponding to high efficiency of
the proposed rectifier is wider than that of the one without
the coupler. Besides, the EM simulation and measurement
efficiencies versus output load are presented in Fig. 15. The
rectifier with the coupler can maintain high efficiency for a
wider output load range than the one without the coupler. The
measured results agree well with the simulated results. There
is still some slight difference between the measurement and
simulation, which is caused by the fabrication tolerance and
diode model inaccuracy.
Table I shows performance comparison among the proposed
rectifier and some prior works which focused on extending
input power range or frequency bandwidth. The proposed
circuit has the widest input power range for RF-dc conversion
efficiency more than 50% (and 70%) compared with the RCN
Authorized licensed use limited to: Guangdong Univ of Tech. Downloaded on April 12,2023 at 08:24:38 UTC from IEEE Xplore. Restrictions apply.
738
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS–I: REGULAR PAPERS, VOL. 64, NO. 3, MARCH 2017
based rectifier in [10]–[12], the rectifier with wide-dynamicrange input matching in [13] and the rectifier based on unequal
power divider in [15]. The rectifier using a pHEMT in [16]
has a wider input power range than our work when the RF-dc
conversion efficiency is over 50%. However, its maximum
efficiency is lower than 60%. Besides, the work in [7] proposes
an analytical diode model for the Class-F rectifier efficiency
and a high efficiency rectifier at 900MHz is designed. It has
a wide input power range of 7.8 dB for efficiency over 70%,
which is also smaller than our design. It is worth pointing
out that most of the rectifiers, such as the one in [7], can use
the proposed circuit structure in this work for performance
improvement. In addition, the proposed rectifier has wider
fractional bandwidth as compared with the rectifiers aiming
at widening the bandwidth in [18], [19]. For example, the
fractional bandwidth corresponding to over 70% efficiency of
the broadband rectifier in [19] is 18.6% while that of the
proposed rectifier is 21.5%. It should be noted that these
previous works only focus on extending the operating input
power range or frequency bandwidth of the rectifiers. But the
proposed work can realize wide input power range, output
load range, operating frequency bandwidth and high rectifying
efficiency at the same time.
V. C ONCLUSION
This paper has presented a novel method for designing
high-efficiency rectifiers with extended input power range, frequency bandwidth and output load range. Theoretical analysis
of the proposed topology has been carried out and the circuit
has been implemented. Comparison among the rectifiers with
and without the coupler, as well as some prior works have
been made, showing improved RF-dc conversion efficiency
and reduced sensitivity to input power, operating frequency,
and output load variations.
[9] K. Niotaki, A. Georgiadis, A. Collado, and J. S. Vardakas, “Dual-band
resistance compression networks for improved rectifier performance,”
IEEE Trans. Microw. Theory Techn., vol. 62, no. 12, pp. 3512–3521,
Dec. 2014.
[10] D. Wang and R. Negra, “A 2.3 GHz single-ended energy recovery
rectifier with stepped-impedance resonator for improved efficiency
of outphasing amplifier,” in Proc. Eur. Microw. Conf., Nuremberg,
Germany, Oct. 2013, pp. 920–923.
[11] J. Xu and D. S. Ricketts, “An efficient, watt-level microwave rectifier
using an impedance compression network (ICN) with applications in
outphasing energy recovery systems,” IEEE Microw. Wireless Compon.
Lett., vol. 23, no. 10, pp. 542–544, Oct. 2013.
[12] T. W. Barton, J. M. Gordonson, and D. J. Perreault, “Transmission line
resistance compression networks and applications to wireless power
transfer,” IEEE J. Emerg. Sel. Topics Power Electron., vol. 3, no. 1,
pp. 252–260, Mar. 2015.
[13] S. H. Abdelhalem, P. S. Gudem, and L. E. Larson, “An RF–DC
converter with wide-dynamic-range input matching for power recovery
applications,” IEEE Trans. Circuits Syst. II, Express Briefs, vol. 60, no. 6,
pp. 336–340, Jun. 2013.
[14] C.-J. Li and T.-C. Lee, “2.4-GHz high-efficiency adaptive power,” IEEE
Trans. Very Large Scale Integr. (VLSI) Syst., vol. 22, no. 2, pp. 434–438,
Feb. 2014.
[15] X. Y. Zhang and Q.-W. Lin, “High-efficiency rectifier with extended
input power range based on two parallel sub-rectifying circuits,” in Proc.
IWS, Shenzhen, China, Apr. 2015, pp. 1–4.
[16] Z. Liu, Z. Zhong, and Y.-X. Guo, “Enhanced dual-band ambient RF
energy harvesting with ultra-wide power range,” IEEE Microw. Wireless
Compon. Lett., vol. 25, no. 9, pp. 630–632, Sep. 2015.
[17] Y. Huang, N. Shinohara, and T. Mitani, “A constant efficiency of
rectifying circuit in an extremely wide load range,” IEEE Trans. Microw.
Theory Techn., vol. 62, no. 4, pp. 986–993, Apr. 2014.
[18] D. Wang, X. A. Nghiem, and R. Negra, “Design of a 57% bandwidth
microwave rectifier for powering application,” in Proc. WPTC, Jeju,
South Korea, May 2014, pp. 68–71.
[19] H. Sakaki and K. Nishikawa, “Broadband rectifier design based on
quality factor of input matching circuit,” in Proc. Asia-Pacific Microw.
Conf., Sendai, Japan, Nov. 2014, pp. 1205–1207.
[20] P. Burasa, N. G. Constantin, and K. Wu, “High-efficiency wideband
rectifier for single-chip batteryless active millimeter-wave identification
(MMID) tag in 65-nm bulk CMOS technology,” IEEE Trans. Microw.
Theory Techn., vol. 62, no. 4, pp. 1005–1011, Apr. 2014.
[21] V. Kuhn, C. Lahuec, F. Seguin, and C. Person, “A multi-band stacked
RF energy harvester with RF-to-DC efficiency up to 84%,” IEEE Trans.
Microw. Theory Techn., vol. 63, no. 5, pp. 1768–1778, May 2015.
[22] D. M. Pozar, Microwave Engineering, 3rd ed. New York, NY, USA:
Wiley, 2005.
R EFERENCES
[1] P. H. Heieh, C. H. Chou, and T. Chiang, “An RF energy harvester with
44.1% PCE at input available power of −12 dBm,” IEEE Trans. Circuits
Syst. I, Reg. Papers, vol. 62, no. 6, pp. 1528–1537, Jun. 2015.
[2] S. Ladan and K. Wu, “Nonlinear modeling and harmonic recycling of
millimeter-wave rectifier circuit,” IEEE Trans. Microw. Theory Techn.,
vol. 63, no. 3, pp. 937–944, Mar. 2015.
[3] Y.-J. Ren and K. Chang, “5.8-GHz circularly polarized dual-diode
rectenna and rectenna array for microwave power transmission,” IEEE
Trans. Microw. Theory Techn., vol. 54, no. 4, pp. 1495–1502, Jun. 2006.
[4] B. Li, X. Shao, N. Shahshahan, N. Goldsman, T. Salter, and
G. M. Metze, “An antenna co-design dual band RF energy harvester,”
IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 60, no. 12, pp. 3256–3266,
Dec. 2013.
[5] M. Roberg, T. Reveyrand, I. Ramos, E. A. Falkenstein, and Z. Popovic,
“High-efficiency harmonically terminated diode and transistor rectifiers,”
IEEE Trans. Microw. Theory Techn., vol. 60, no. 12, pp. 4043–4052,
Dec. 2012.
[6] S. Ladan, A. B. Guntupalli, and K. Wu, “A high-efficiency 24 GHz
rectenna development towards millimeter-wave energy harvesting and
wireless power transmission,” IEEE Trans. Circuits Syst. I, Reg. Papers,
vol. 61, no. 12, pp. 3358–3366, Dec. 2014.
[7] J. Guo, H. Zhang, and X. Zhu, “Theoretical analysis of RF-DC conversion efficiency for class-F rectifiers,” IEEE Trans. Microw. Theory
Techn., vol. 62, no. 4, pp. 977–985, Apr. 2014.
[8] T.-W. Yoo and K. Chang, “Theoretical and experimental development of
10 and 35 GHz rectennas,” IEEE Trans. Microw. Theory Techn., vol. 40,
no. 6, pp. 1259–1266, Jun. 1992.
Xiu Yin Zhang (S’07–M’10–SM’12) was born in
Hubei, China. He received the B. S. degree from
Chongqing University of Posts and Telecommunications, China, the M.S. degree in electronic engineering from South China University of Technology,
Guangzhou, China, in 2006, and the Ph.D. degree in
electronic engineering from City University of Hong
Kong, China, in 2009.
From 2001 to 2003, he was with ZTE Corporation,
Shenzhen, China. He was a Research Assistant from
July 2006 to June 2007 and a Research Fellow from
September 2009 to February 2010 with the City University of Hong Kong.
He is currently a full Professor with the School of Electronic and Information
Engineering, South China University of Technology. He has authored or
coauthored more than 100 internationally referred journal and conference
papers. His research interests include microwave circuits and antennas, LTCC,
wireless power transfer.
Dr. Zhang has served as a Technical Program Committee (TPC) member and
session organizer/chair for a number of conferences. He has been a regular
reviewer of several international journals including 6 IEEE Transactions and
2 IEEE Letters. He was a recipient of the Young Scholar of the Changjiang
Scholars Program of Chinese Ministry of Education, the Top-notch Young
Professionals of National Program of China, the National Science Foundation
for Outstanding Young Scholars of China and the Guangdong Natural Science
Fund for Distinguished Young Scholar. He was the supervisor of several
conference best paper award winners.
Authorized licensed use limited to: Guangdong Univ of Tech. Downloaded on April 12,2023 at 08:24:38 UTC from IEEE Xplore. Restrictions apply.
ZHANG et al.: HIGH-EFFICIENCY BROADBAND RECTIFIER WITH WIDE RANGES OF INPUT POWER AND OUTPUT LOAD
Zhi-Xia Du was born in Guangdong, China.
He received the B.S. degree in applied physics from
South China University of Technology, Guangzhou,
in 2014, where he is currently working toward the
Ph.D. degree in electronic engineering in the School
of Electronic and Information Engineering.
His research interests include microwave circuits
and wireless power transfer.
He was awarded the Best Student Paper Prize in
the 2015 National Conference on Microwave and
Millimeter Wave Technology (NCMMW).
739
Quan Xue (M’02–SM’04–F’11) received the B.S.,
M.S., and Ph.D. degrees in electronic engineering from the University of Electronic Science and
Technology of China (UESTC), Chengdu, in 1988,
1990, and 1993, respectively. In 1993, he joined
the UESTC as a Lecturer. He became a Professor
in 1997. From October 1997 to October 1998, he
was a Research Associate and then a Research
Fellow with the Chinese University of Hong Kong.
In 1999, he joined the City University of Hong
Kong where he is currently a Chair Professor of
Microwave Engineering. He also serves the University as the Director of
Information and Communication Technology Center (ICTC center), and the
Deputy Director of State Key Lab of Millimeter Waves (Hong Kong). He was
the Associate Vice President (Innovation Advancement and China Office) from
June 2011 to January 2015.
He has authored or coauthored more than 260 internationally referred journal
papers and more than 100 international conference papers. His research
interests include microwave passive components, active components, antenna,
microwave monolithic integrated circuits (MMIC, and radio frequency integrated circuits (RFIC), etc. Prof. Xue served the IEEE as an AdCom member
of MTT-S from 2011-2013 and an Associate Editor of IEEE T RANSAC TIONS ON M ICROWAVE T HEORY AND T ECHNIQUES (2010-2013), and an
Associate Editor of IEEE T RANSACTIONS ON I NDUSTRIAL E LECTRONICS
(2010-present).
Authorized licensed use limited to: Guangdong Univ of Tech. Downloaded on April 12,2023 at 08:24:38 UTC from IEEE Xplore. Restrictions apply.