Chulhun Seo

High-Q metamaterial interdigital transmission line based on complementary spiral resonators for low phase noise voltage-controlled oscillator

In this study, the high-quality factor ( Q ) metamaterial interdigital transmission line (TL) based on the complementary spiral resonators (CSRs) is presented for reducing the phase noise of the voltage-controlled oscillator (VCO). The high- Q metamaterial TL is realised by adopting the array of the CSRs etched on the ground plane and the interdigital centre line on the signal plane. The interdigital centre line on the signal plane has been used to obtain higher Q value than that of the conventional implementation. The resonance properties and inherent Q value saturation of the proposed high- Q metamaterial interdigital TL have been analysed as follows: width of the centre line on the signal plane, dimensions of the CSRs, current directions between the CSRs, number of the unit cell-pair of the CSRs and whether or not there is the interdigital structure. The phase noise and tuning range of the proposed VCO are -127.50 to -124.87-dBc/Hz at 100-kHz and 5.744-5.86-GHz.

CMOS class-E power amplifier (1.8-GHz) with an additional thin-film technology

A 1.8-GHz power amplifier is implemented using the 0.18-μm Radio Frequency (RF) Complementary Metal Oxide Semiconductor (CMOS) process. An additional thin-film technology on a separate substrate is used to design the output matching network for high efficiency. To minimise the number of bond-wires, a single differential power stage is used. The output matching network was completed with the proposed load impedance transformer and an Metal Insulator Metal (MIM) capacitor using additional thin-film technology. The amplifier achieved a drain efficiency of 50.5 μ at a maximum output power of 31.6 μdBm at 1.81 μGHz.

Design of Ultra-wide Band-pass Filter Based on Metamaterials Applicable to Microwave Photonics

We designed an ultra-wide band-pass filter applicable to microwave reflectometry for KSTAR (Korea Superconducting Tokamak Advanced Research) and to microwave photonics. The proposed ultra-wide band-pass filter exhibits a metamaterial structure characterized by a wide band, low insertion loss, and high skirt selectivity. The proposed filter is applied to enhance the linearity of reflectometry at the output of a VCO (voltage controlled oscillator). The pass-band of the proposed filter is observed at 18~28 GHz, and the out-of-band rejection is below 20 dB. Further, we constructed an unwrapped negative phase of S(2, 1) to verify the characteristics of the metamaterial. The under- and upper-band at lower limits of the pass-band are left- and right-handed, respectively. The group delay of the filter is less than 0.5 ns.

Microstrip Square Open Loop Metamaterial Resonator and Rat Race Coupler for Low Phase Noise Push-Push VCO

In this paper, a novel low phase noise voltage-controlled oscillator (VCO) using metamaterial structure and rat race coupler is presented for reducing the phase noise without the reduction of the frequency tuning range. The metamaterial structure has been realized by microstrip square open loop double split ring resonator (SRR). The rat race coupler shows slightly higher transmission compared to a Wilkinson combiner and is, therefore, used instead to improve the performances of VCO. By providing these unique modifications, the proposed push-push VCO has a phase noise of -126.30~-124.83 dBc/Hz at 100 kHz in the tuning range of 5.672~5.800 GHz.

Design of a Highly Efficient Broadband Class-E Power Amplifier with a Low Q Series Resonance

This work presents a method used for designing a broadband class-E power amplifier that combines the two techniques of a nonlinear shunt capacitance and a low quality factor of a series resonator. The nonlinear shunt capacitance theory accurately extracts the value of class-E components. In addition, the quality factor of the series resonator was considered to obtain a wide bandwidth for the power amplifiers. The purpose of using this method was to produce a simple topology and a high efficiency, which are two outstanding features of a class-E power amplifier. The experimental results show that a design was created using from a 130 to 180 MHz frequency with a bandwidth of 32% and a peak measured power added efficiency of 84.8%. This prototype uses an MRF282SR1 MOSFET transistor at a 3-W output power level. Furthermore, a summary of the experimental results compared with other high-efficiency articles is provided to validate the advantages of this method.

Design of a Metamaterial Absorber for High Isolation of a WCDMA Indoor Repeater Antenna

In this paper, an absorber based on metamaterial is proposed to improve the isolation of conventional WCDMA indoor repeater antenna. The proposed absorber is composed of Double Split Ring Resonators(DSRRs) and Complementary Spiral(CS) structure. The proposed absorber based on metamaterial is and absorption is about 94 % at 2.2875 GHz. The proposed antenna, which proposed absorber is applied to conventional WCDMA indoor repeater antenna, has isolation over 85 dB. Isolation is improved more than 10 dB compared with the conventional antenna. The VSWR is lower than 2 at WCDMA band from 1.92 GHz to 2.17 GHz. The radiation patterns are E-plane and H-plane, respectively. And, the gain is more than 6 dBi. The volume of proposed antenna with absorber based on metamaterial is .

Wireless Energy Transmission High-Efficiency DC-AC Converter Using High-Gain High-Efficiency Two-Stage Class-E Power Amplifier

In this paper, a high-efficiency DC-AC converter is used for wireless energy transmission. The DC-AC convertter is implemented by combining the oscillator and power amplifier. Given that the conversion efficiency of a DC-AC converter is strongly affected by the efficiency of the power amplifier, a high-efficiency power amplifier is implemented using a class-E amplifier structure. Also, because of the low output power of the oscillator connected to the input stage of the power amplifier, a high-gain two-stage power amplifier using a drive amplifier is used to realize a high-output power DC-AC converter. The high-efficiency DC-AC converter is realized by connecting the oscillator to the input stage of the high-gain high-efficiency two-stage class-E power amplifier. The output power and the conversion efficiency of the DC-AC converter are 40.83 dBm and 87.32 %, respectively, at an operation frequency of 13.56 MHz.

The Open Loop Multiple Split Ring Resonator Based Voltage Controlled Oscillator in 0.13 um CMOS

In this paper, a novel voltage-controlled oscillator(VCO) using the open loop multiple split ring resonator(OLMSRR) is presented for improving the phase noise, implemented in 130 nm CMOS technology. Compared with the conventional CMOS LC resonator, the proposed CMOS OLMSRR has the larger coupling coefficient value, which makes a higher Q-factor, and has improved the phase noise of the VCO. The proposed CMOS VCO based OLMSRR has the phase noise of -99.67 dBc/Hz @ 1 MHz in the oscillation frequency. Compared with the VCO using the conventional CMOS LC resonator and the proposed VCO using the CMOS OLMSRR structure has been improved in 7 dB. The prototype 24 GHz CMOS VCO is implemented in 130 nm CMOS and occupies a compact die area of .

Low Phase Noise VCO Using the Metamaterial Broadside Coupled Spiral Resonator

In this paper, a novel voltage-controlled oscillator(VCO) using the metamaterial broadside coupled spiral resonators(BC-DSRs) is presented for reducing the phase noise. For reducing of the phase noise, the series spiral structures have been applied for the signal plane and ground plane at each in order to have the large coupling. Compared with the conventional VCO, the proposed VCO has the larger coupling coefficient constant, which makes a higher Q-factor and has reduced the phase noise of the VCO. The proposed VCO has the phase noise of /Hz at 100 kHz in the tuning range, . The figure of merit(FOM) of this VCO is /Hz at 100 Hz in the same tuning range, respectively.

Low Phase Noise Push-Push VCO Using Microstrip Square Open Loop Resonator and Tunable Negative Resistance

In this paper, a novel push-push voltage-controlled oscillator(VCO) using microstrip square open loop resonator and tunable negative resistance is presented. The microstrip square open loop resonator has the large coupling coefficient value, which makes a high Q value, and has reduced phase noise of VCO. The VCO with 1.8V power supply has phase noise of in the tuning range, . The FOM of this VCO is in the same tuning range. When it has been compared with single-ended VCO using microstrip square open loop resonator, and push-push oscillator using microstrip line resonator, the reduced phase noise has been -8.51dB, and -33.67dB, respectively.