Chan-Wang Park

FPGA-implementation of high-speed MLP neural network

This paper presents a new high-speed FPGA implementation of a pipelined adaptive multilayer perceptron (MLP). The proposed approach is a fully parallel architecture based on the delayed backpropagation algorithm, which permits to reduce the critical path and consequently increases the operating frequency. Results obtained with nonlinear function approximation show that this pipelined parallel architecture is four times faster than the conventional one.

Concurrent tri-band GaN HEMT power amplifier using resonators in both input and output matching networks

This paper presents a novel method by using resonators in both input and output matching networks to design a tri-band GaN HEMT power amplifier. Two parallel resonators in series as one frequency selection element are used for each operation frequency. By applying this frequency selection element in both input and output matching networks constructed with microstrip line, tri-band matching network is realized. With our proposed frequency selection element, we can use the conventional L-type structure to design matching network for three frequencies so that the design analysis procedure is easier. We also propose a new simplified output matching network by using bias line to match the output impedance to reduce the number of resonators. To demonstrate our method, we fabricate a tri-band power amplifier that can work at 1 GHz, 1.5 GHz, and 2.5 GHz concurrently. Experimental results show that the output power is 39.8 dBm, 40.8 dBm, and 39.2 dBm with 56.4%, 58.3%, and 43.4% power added efficiency (PAE) at 1 GHz, 1.5 GHz and 2.5 GHz, respectively.

Substrate integrated waveguide (SIW) power amplifier using CBCPW-to-SIW transition for matching network

In this paper, for the first time a novel substrate integrated waveguide (SIW)-based 10W power amplifier (PA), designed with conductor-backed coplanar waveguide (CBCPW)-to-SIW transition matching network (MN), is presented. Transition between CBCPW and SIW is employed for both input and output MN designs, the proposed SIW PA can be easily connected with any microstrip or SIW-based circuits. Asymmetrical and symmetrical types of CBCPW-to-SIW transition MN are proposed. Output SIW-based MN is designed with asymmetrical structure by using one inductive metalized post and input SIW-based MN is designed with symmetrical structure by using two identical inductive metalized posts. One SIW-based 10W PA using GaN HEMT at 3.62 GHz is designed, fabricated, and measured. Measured results show that the maximum power added efficiency (PAE) is 54.24 % with 39.74 dBm output power and the maximum gain is 13.31 dB. At the design frequency of 3.6 GHz, the size of proposed SIW-based PA is comparable with other microstrip-based PAs.

FPGA-implementation of an adaptive neural network for RF power amplifier modeling

In this paper, we propose an architecture for FPGA-implementation of neural adaptive neural network RF power behavioral modeling. The real-valued time-delay neural network (RVTDNN) and the backpropagation (BP) learning algorithm were implemented on FPGA using Xilinx System Generator for DSP and the Virtex-6 FPGA ML605 Evaluation Kit. Performances obtained with 16-QAM modulated test signal and material resource requirement are presented for a network of six hidden layer neurons.

High power added efficiency power amplifier with harmonic controlled by UWB filter with notched band at 6.42 GHz

A high power added efficiency (PAE) GaN inverse Class F PA (power amplifier) at 2.14 GHz with UWB (Ultra Wideband) bandpass notched filter is designed, fabricated and tested. For this amplifier, second harmonic and fourth harmonic are rejected by the bias circuit, while third harmonic is controlled by a UWB bandpass notched filter and fifth harmonic is tuned by a traditional λ/4 transmission line at 10.7 GHz. By applying this novel filter, third harmonic can be suppressed while for fundamental frequency, the filter works as a 50-Ohm transmission line with little insertion loss. With the interdigital hairpin line structure of the filter, the blocking capacitor is not needed in the load matching network. Compared with the conventional λ/4 transmission line at third harmonic, the size of this amplifier circuit is reduced. The measured PAE is 61.6% with 38.8 dBm output power at 2.14 GHz. The maximum gain is 15.9 dB.

Novel wideband GaN HEMT power amplifier using microstrip radial stub to suppress harmonics

In this paper, a novel wideband GaN HEMT power amplifier (PA) using microstrip radial stub (MRS) in both input and output matching networks to suppress harmonic components of 2.14 GHz is analyzed, fabricated, and tested. The angle subtended by MRS and the bottom length of MRS are analyzed for harmonic suppressing purpose. The wideband harmonic suppressing characteristic of MRS is compared with normal 50 Ohm quarter-wave rectangular stub. The second and third harmonics of 2.14 GHz are suppressed by −38.37 dB and −29.53 dB, respectively. −15 dBc suppressing bandwidth over 1.32 GHz at both harmonic bands is obtained. By using the proposed MRS in both input and output matching network, the measured maximum power added efficiency (PAE) is 80.52% with 40.53 dBm output power at 2.14 GHz. At least 50% PAE and 37 dBm output power over a 12% bandwidth from 2 GHz to 2.26 GHz is achieved. The maximum gain is 20.25 dB.

An improved detector topology for a rectenna

This paper introduces an improved detector topology which is used to design the rectifier that is a part of a rectenna, operating in the S-band. Our proposition adds a third diode into the conventional half bridge detector, leading to improve the output DC voltage and to reduce the harmonics power level. Then, a rectifying circuit is built using two approaches. The first rectifier is based on a HSMS2822 doubler with a HSMS2820 diode. While the second rectifier uses a HSMS282P quad. We have achieved a RF-DC conversion efficiency of 57% at 2.45 GHz and of 72% at 2.1 GHz, respectively for the first and the second rectifier.

Novel substrate integrated waveguide (SIW)-based power amplifier using SIW-based filter to suppress up to the fourth harmonic

In this paper, a novel 10W substrate integrated waveguide (SIW)-based GaN HEMT power amplifier (PA) using SIW-based filter in both input and output matching networks to suppress up to the 4th harmonic of 2.14 GHz is analyzed, fabricated, and tested. By connecting two SIW-based stubs with one microstrip-based stub, applying the cutoff frequency characteristic of post-wall waveguide structure, the SIW-based filter which can suppress up to the 4th harmonic of 2.14 GHz is achieved. With measured result, the insertion loss of the 2nd, 3rd, and 4th harmonics of 2.16 GHz is better than 33 dB, 15 dB, and 20 dB, respectively. Using this proposed SIW-based filter in both input and output matching networks to suppress harmonic components, one SIW-based PA designed at 2.14 GHz is fabricated and tested. Measured results show that, the maximum power added efficiency (PAE) is 61.4% with output power 39.1 dBm at 2.14GHz. The measured maximum gain is 16.1 dB with output power 33.6 dBm.

Tri-band Wilkinson power divider using resonators

This paper presents a method by using resonators to design a tri-band Wilkinson power divider. We employ the conventional Wilkinson power divider structure working at higher frequency f1 (2.5GHz) as the basic design. In order to achieve good performance of the other two frequencies, we use an open-circuit stub connected with a resonator for the middle frequency f2 (1.5GHz) and cascade another one with the same idea for the lower frequency f3 (1GHz). By applying this kind of frequency control element (stubs with resonators) in a π -shaped structure and putting them inside the conventional Wilkinson divider, topology keeps the compactness. Applications of three distinctive bands for Wilkinson power divider are analyzed by employing 2.5D EM simulator and these results are in agreement with measured ones.

Dual-band GaN HEMT power amplifier using resonators in matching networks

In this paper, we employ a novel method by using resonators with microstrip lines to design a dual-band GaN HEMT power amplifier. At both input and output matching networks, we add parallel resonators between series microstrip lines and open-circuited stubs to realize the dual-band operation. With our proposed structure, we can use the conventional L-type structure to design matching network for each operation frequency so that the design is easier. By using just one transistor without any tunable electronic element or switch, a novel dual-band class AB power amplifier working at 1.5 GHz and 2.4 GHz is designed and fabricated to demonstrate our proposed simple method. With dual-band matching networks using resonators, the experimental results show the output power 40.3 dBm and 39.05 dBm with power added efficiency (PAE) 55.63% and 40.25% at 1.5 GHz and 2.4 GHz, respectively.