Three-way Combiner Research Articles

Two-Layer Three-Way Horst Power Divider and Combiner Based on Microstrip Line With Fixed Characteristic Impedance

In this letter, a two-layer three-way power divider/combiner (PDC) based on a fixed impedance transmission line is presented. The design is optimized through even/odd modes analysis. To provide design guidelines, graphical representations with closed-form equations are also provided. The theoretical bandwidth is estimated according to a performance criterion that takes into account the balance between isolation and input matching. The two-layer configuration provides better isolation between opposite ports despite the compact size. To validate the simulations, the three-way PDC is fabricated and measured. The measured results demonstrate excellent matching, isolation, and transmission performance with an overall fractional bandwidth (FBW) of 20%, which is consistent with the calculated bandwidth.

Design of a 3-way wide-band in-phase power combiner for UHF applications

ABSTRACT In this work, a three-way wide-band in-phase power combiner for ultra-high frequency band (UHF) applications is presented. The proposed power combiner is a modification of the conventional 3-way Wilkinson power combiner. In the proposed power combiner, the floating isolation-resistors are replaced by coaxial baluns and 50-Ω terminations. This configuration is suitable for high-power applications as flange-mount terminations exhibit superior frequency response and heat conduction compared to floating resistors. The coaxial baluns, connected in the star configuration, help for isolation and input-ports matching. The characteristic impedance of coaxial baluns is 50-Ω and is matched to the terminations. This property serves for a broad bandwidth. Even- and odd-mode methods are employed for the analysis and design of the power combiner. To validate the design method and the theoretical results, a three-way power combiner is fabricated, which consists of microstrip, coaxial-cables and some 50-Ω terminations. The combiner provides 20-dB isolation and summing-port return-loss over an octave bandwidth. The operating frequency is between 470 and 860 MHz, which is used for digital video broadcasting–terrestrial (DVB-T).

A 25.1 dBm 25.9-dB Gain 25.4% PAE X-band Power Amplifier Utilizing Voltage Combining Transformer in 65-nm CMOS

We present an X-band two-stage power amplifier (PA) in 65-nm CMOS process using a transformer (TF)-based voltage combining technique (VTC) which achieves the highest figure of merit (FOM) among recently reported CMOS PAs. The PA architecture is constructed with two-stage push-pull amplifiers with a three-way voltage power combiner and splitter which play the main role to achieve outstanding performance. The power combining was applied in the voltage domain to increase the output device size aiming at boosting the output power of the CMOS PA. We constructed a compact two-stage PA with a push-pull structure with conjugate matchings at the input, inter-stage, and output with the capacitive neutralization technique to improve the power gain and drain efficiency. Working under a 1.2-V supply with DC quiescent current of 865-mA, the proposed PA achieved a maximum saturated output power of 25.1 dBm with a 1-dB power bandwidth of 3-GHz from 8.4-GHz to 11.4-GHz, a peak power added efficiency (PAE) of 25.4% at 10.2 GHz, a power gain of 25.9-dB at 9.5-GHz with a 3-dB gain bandwidth of 2-GHz (8.7-10.7 GHz). The total chip size is 0.9 mm2, and the core size excluding pads is only 0.342 mm2.

A Watt-Level Phase-Interleaved Multi-Subharmonic Switching Digital Power Amplifier

This article presents a multi-subharmonic switching (SHS) digital power amplifier (PA) architecture for enhancing power back-off (PBO) efficiency while achieving watt-level output power. The proposed phase-interleaved architecture provides the inherent cancellation of the subharmonic components in the PBO region, alleviating the burden of the matching network. The proposed multi-SHS scheme can be further combined with a class-G operation to create a greater number of efficiency peaks in the PBO region. A transformer-based, three-way power combiner and a triple-stacking class-D driver are utilized to obtain watt-level output power. The proof-of-concept PA prototype is implemented with a switched-capacitor PA (SCPA) architecture in 65-nm CMOS and achieved 30-dBm peak power at 1.9 GHz, with 45.9%/41.3%/35.3%/32.2%/24.2% drain efficiency located at 0-, -3.5-, -7.0-, -9.5-, and -12-dB PBO, respectively. The average efficiency was 31.4% in real-time operation with a 7.2-dB peak-to-average power ratio (PAPR) modulated signal.

Contra-Directional Ridge Waveguide Couplers: Design and Applications

This article presents novel wideband contra-directional couplers based on single conductor ridge waveguide, and their applications. The couplers exhibit wide bandwidths and tight coupling while occupying very small volume due to the compactness of ridge waveguides. The methodology to design the couplers is presented. It is inspired by the even and odd modes used to design TEM coupled lines couplers but implemented with TE modes in this novel approach. The design starts with designing the coupling section in a quadruple-ridge waveguide that supports two independent even and odd TE modes. Proper choice of the cross section allows the designer to achieve the required impedance levels for the required coupling values. An S-band proof of concept prototype of a single coupler was synthesized, fabricated, and tested, demonstrating excellent measured results without any tuning. The couplers can be exploited in versatile applications, such as power sampling, beamforming, or high-power combiners. As an additional proof of concept design, a C-band three-way combiner was also designed and tested, showing the potential of the novel coupler for different applications.

High-efficiency three-way Ka-band waveguide unequal power combiner

This article presents the design, simulation and characterisation of a novel high-efficiency Ka-band (32.05 ± 0.25 GHz) rectangular waveguide three-way serial combiner for monolithic microwave integrated circuit power amplifiers (PAs) with unequal output power. The combiner presented here is suited for low data rate communications from deep space using a single carrier with constant envelope (amplitude) type modulation. The three-way combiner consists internally of two branch-line hybrids connected in series by a short length of waveguide. The two branch-line hybrids were each designed to combine two input signals that are equal in phase and with an amplitude ratio of two, although in general the amplitude ratio could be arbitrary. The combiner was fabricated in an E -plane split-block arrangement and precision machined from blocks of aluminium with standard WR-28 waveguide ports. S -parameter measurements demonstrated a close achievement of the design goals. The measured return loss at the output port was greater than 16 dB and the isolation between the three input ports of the three-way combiner were greater than 22 dB. The combining of three PAs was successfully demonstrated in which the measured combining efficiency was greater than 90% at the centre frequency of 32.05 GHz.

HIGH EFFICIENCY KA-BAND MMIC SSPA POWER COMBINER FOR NASA'S SPACE COMMUNICATIONS

In this paper, we will review the design, construction and performance of the two-way Ka -band waveguide branch-line and asymmetric magic- T based unequal power combiners. The manufactured combiners were designed to combine input signals that are equal in phase and with an amplitude ratio of two. Next, the design, construction and performance of a three-way branch-line unequal power combiner, achieved by serially interconnecting two 2-way branch-line hybrids and optimizing the dimensions using software tools, is presented. The application of the two-way and three-way combiners for combining the output from two or three MMIC PAs was demonstrated. The observed efficiencies for all three power combining configurations are 90 percent or greater at Ka -band (31.8 to 32.3 GHz).

N -way planar high-power combiner design for RF power amplifiers

The complete design using a novel technique for an N-way planar high-power combiner is introduced for radio‐frequency (RF) power amplifiers (PAs) at high-frequency (HF) range for the first time. On the basis of this design technique, a three-way planar combiner is simulated, designed and built on a ceramic-based material that allowed a surface-mount application. Design charts for a thermally reliable operation under high-power conditions are given. The simulated and measured results are compared and found to be very close. The design technique for planar combiners introduced here can be used for RF PAs to obtain power level in the several-kilowatt range in HF communication for industrial and military applications.

Three- and five-way low loss phase combiners for power amplifier sharing in cellular networks

Novel low loss 3×3-way and 5×5-way phase combiners for power amplifier load balancing in wireless network cells are presented. Based on an air-filled coaxial multiring structure, the designs combine very low insertion loss with compact physical profile. The concept is studied for the PCS (personal communication service) transmit band in the range 1.91–1.99 GHz by simulation. Measurements validate the predicted very low insertion loss for the three-way combiner of 0.05 dB, while return loss and port isolation are both better than 25 dB. Simulations exhibit, with 0.15 dB insertion loss, a similar performance for the five-way device. Return loss and port isolation are better than 23 dB in this case.

A Low-Loss Serial Power Combiner Using Novel Suspended Stripline Couplers

A low-loss serial power combiner using suspended stripline is described. It consists of novel broadside-coupled directional couplers which have shunt capacitances at the edges of the coupled sections. These additional shunt capacitances compensate for poor directivities of the couplers because of inhomogeneous dielectric in suspended stripline structure. The fabricated three-way power combiner has achieved good performance with insertion loss less than 0.23 dB over a bandwidth of 10% in 2 GHz band.

A compact 1.7 - 2.1 GHz three-way power combiner using microstrip technology with better than 93.8% combining efficiency

This letter presents the design and measured performance of a microstrip three-way power combiner. The combiner is designed using the conventional Wilkinson topology with the extension to three outputs, which has been rarely considered for the design and fabrication of V-way combiners. It is shown that with an appropriate design approach, the main drawback reported with this topology (nonplanarity of the circuit when N > 2) can be minimized to have a negligible effect on the circuit performance and still allow an easy MIC or MHMIC fabrication.