• Current Optics and Photonics
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• v.2 no.2
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• pp.134-139
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• 2018

A novel approach for frequency-tripling vector signal generation via balanced detection without precoding and optical filter is proposed. The scheme is mainly utilizing an integrated dual-polarization quadrature phase shift keying (DPQPSK) modulator. In the DPQPSK modulator, one QPSK modulator is driven by an RF signal to generate high-order optical sidebands, while the other QPSK modulator is modulated by I/Q data streams to produce baseband vector signal as an optical carrier. After that, a frequency-tripling 16-quadrature-amplitude-modulation (16QAM) vector millimeter-wave (mm-wave) signal can be obtained by balanced detection. The proposed scheme can reduce the complexity of transmitter digital signal processing. The results show that, a 4 Gbaud baseband 16QAM vector signal can be generated at 30 GHz by frequency-tripling. After 10 km single-mode fiber (SMF) transmission, the constellation and eye diagrams of the generated vector signal perform well and a bit-error-rate (BER) below than 1e-3 can be achieved.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.404-404
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• 2004

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.4
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• pp.32-42
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• 2010

In this paper, we represent considering parameters for design of a Cartesian vector modulator predistorter to maximize linearity improvement of the predistorter and propose an advanced Cartesian vector modulator predistrotrer with nonlinear starting point control circuit. In order to confirm the performance of the proposed predistorter, the predistorter is applied to power amplifier with 15 W output power for 2.5 GHz band mobile WiMax 1-FA signal. From the measured results, ACLR of -45.3 dBc with 4 dB improvement of ALCR compared with the previous predistorter is obtained and linearity improvement range is also extended.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.575-583
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• 2003

In thesis we applied the short or open reflection type for IQ vector modulator The open or short type is operated even exception of other redundancy circuit. Generally IQ vector modulator uses MESFET in performing reflection open or short, then minus voltage which is having complex structure is required to operate MESFET via IQ signal. However BJT can be substituted for MESFET, BJT is improved characteristics like as cutoff frequency, electron mobility and so on. We used BJT in IQ vector modulator which is compatible with TTL level in I,Q digital signal, and attached AGC function. We got the result of operations within ${\pm}$ 1$^{\circ}$ phase and ${\pm}$ 0.6 dB amplitude Variation With full range of 20 dB and Variation of ${\pm}$ 6$^{\circ}$ Phase and ${\pm}$ 0.5 dB amplitude Versus full temperature range.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.715-717
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• 1999

본 논문에서는 feedforward 선형 증폭기에서의 지연 불일치에 의한 효과를 최소화하기 위한 등화기의 차수 결정에 관하여 수학적 접근과 모의실험을 하였다. 현재 feedforward 선형 증폭기에서 주로 사용하는 vector modulator는 지연 불일치에 확실한 개선을 이루지 못하고 있다. 이것을 극복하고자 vector modulator를 등화기로 대체하고 증폭기와 시지연선의 최대시간불일치와 sampling frequency와의 관계로 등화기의 차수를 결정하여 지연 불일치에 의한 오류 제거능력을 향상시켰다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.7
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• pp.734-740
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• 2003

In this paper, A Vector Modulator based a wideband analog phase shifter is realized with four P-I-N diode attenuators, an asymmetric coupled line coupler, a symmetric coupled line coupler, and a power combiner. Simple configuration to have advantages in cost, size, power, and the number of passive circuits is presented. The phase variation due to phase and amplitude error of a P-I-N diode attenuator is derived and used to optimize the overall circuit. The phase shifter shows a total phase shift of 360$^{\circ}$, a 8.2$^{\circ}$maximum phase error, and a 16${\pm}$2.5 dB insertion loss over the wide frequency range of 1 GHz to 3 GHz.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.3
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• pp.313-321
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• 2014

A low-power low-cost polar transmitter for EDGE is designed in $0.18{\mu}m$ CMOS. A differential delta-sigma modulator (DSM) tunes a three-terminal voltage-controlled oscillator (VCO) to perform RF phase modulation, where the VCO tuning curve is digitally pre-compensated for high linearity and the carrier frequency is calibrated by a dual-mode low-power frequency-locked loop (FLL). A digital intermediate-frequency (IF) pulse-width5 modulator (PWM) drives a complementary power-switch followed by an LC filter to achieve envelope modulation with high efficiency. The proposed transmitter with 9mW power dissipation relaxes the time alignment between the phase and envelope modulations, and achieves an error vector magnitude (EVM) of 4% and phase noise of -123dBc/Hz at 400kHz offset frequency.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.3
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• pp.48-55
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• 2006

This paper describes the antenna based GPS anti-jamming technology called CRPA(Controlled Reception Pattern Antenna), which used $2{\times}2$ array elements. In this system, the main functions are the antenna complex weight control and the GPS digital I/Q VM(Vector Modulator). To update the VM's I/Q complex weights, the PC based DAC(Digital to Analog Converter) module was also used and the two analog output voltages were applied to the $2{\times}2$ array elements to synthesize the null pattern. In the study, we also simulated the $2{\times}2$ GPS array null patterns to compare the null depth with experimental results. The VM was also modified at the frequency of 1.575GHz for the GPS L1 and controlled by the PC based VM software.

• Journal of Power Electronics
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• v.16 no.1
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• pp.388-397
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• 2016

An error-compensated pulse width modulator (ECPWM) is proposed to improve the baseband harmonic performance and the switching loss of voltage source inverters (VSIs). Selecting between harmonic distortion and switching loss is a design tradeoff in the conventional space vector pulse width modulation. In this work, an accumulated difference in produced and desired phase voltages is considered to adjust the reference signal. This mechanism can compensate for the voltage error in the previous carrier period. With error compensation every half-carrier period, the proposed ECPWM allows one-half reduction in carrier frequency without scarifying baseband harmonic distortion. The proposed modulator is applied to a three-phase VSI with R-L load and a motor-speed-control system for experiments. The measured efficiency and operating temperature of switches confirm the effectiveness of the proposed scheme.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.847-851
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• 2011

In this paper, a novel IQ modulator that precisely controls the magnitude and phase of input signals is proposed. The proposed IQ modulator consists of low phase deviation attenuators, a splitter, and a combiner. In order to overcome the phase deviation characteristics found in conventional attenuators, a novel phase compensation technique has been adopted and mathematically analyzed. Linear vector arrays along the center point with large magnitude output signal variations in a full $360^{\circ}$ phase control are achieved on a polar plane by the proposed IQ modulator.