• Journal of IKEEE
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• v.15 no.2
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• pp.129-133
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• 2011

A spread spectrum clock generation is an efficient way to reduce electro-magnetic interference (EMI) radiation in modern mixed signal chip systems. The proposed circuit generates the spread spectrum clock by directly injecting the modulation voltage into the voltage-controlled oscillator (VCO) current source for SATA II. The resulting 33KHz modulation profile has a Hersey-Kiss shape with a rounded peak. The chip has been fabricated using $0.18{\mu}m$ CMOS process and test results show that the proposed circuit achieves 0.509% (5090ppm) down spreading at 1.5GHz and peak power reduction of 10dB. The active chip area is 0.36mm ${\times}$ 0.49mm and the chip consumes 30mW power at 1.5GHz.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.6
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• pp.404-409
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• 2014

This paper presents a Spread Spectrum Clock Generator (SSCG) based on Relaxation oscillator using Up/Down Counter. The current is controlled by a counter and the spread spectrum of the Relaxation Oscillator. A Relaxation Oscillator with temperature compensation using the BGR and ADC is presented. The current to determine the frequency of the Relaxation Oscillator can be controlled. The output frequency of the temperature can be compensated by adjusting the current according to the temperature using the code that is the output from the ADC and BGR. EMI Reduction of SSCG is 11 dB, and Spread down frequency is 150 kHz. The current consumption is $600{\mu}A$ from 5V and the operating frequency is from 2.3 MHz to 5.75 MHz. The rate of change of the output frequency with temperature was approximately ${\pm}1%$. The SSCG is fabricated in a 0.35um CMOS process with active area $250um{\times}440um$.

• Journal of IKEEE
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• v.15 no.1
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• pp.23-28
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• 2011

This paper describes design and implementation of a spread spectrum clock generator(SSCG). The proposed architecture generates the spread spectrum clock controlling a input voltage signal for VCDL(Voltage Controlled Delay Line). Spread charge pump is controlled by the SSC modulation logic block provides a control signal to VCDL through LPF in DLL. By using this architecture, chip area and power consumption can be reduced because it is not necessary additional circuit to control modulation rate. This circuit has been designed and fabricated using the UMC 0.25um CMOS technology. The chip occupies an area of 290${\times}$120um^2.

• Journal of IKEEE
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• v.17 no.4
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• pp.537-543
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• 2013

This paper proposed a low EMI spread spectrum clock generator (SSCG) using discontinuous frequency modulation technique. The proposed SSCG is designed for triangular frequency modulation with high modulation depth. When the maximum time interval error (MTIE) of the SSCG is higher than given limit, the output frequency of SSCG is divided by two and used for reducing the time interval error (TIE). This discontinuous frequency modulation technique can effectively reduce the EMI within given limit. The simulated EMI of proposed SSCG was reduced by 18.5dB than that of conventional methods.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.4
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• pp.282-290
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• 2013

This paper describes a spread spectrum clock generator (SSCG) circuit for DisplayPort 1.2 standard. A Hershey-Kiss modulation profile is generated by dual sigma-delta modulators. The structure generates various modulation slopes to shape a non-linear modulation profile. The proposed SSCG for DisplayPort 1.2 generates clock signals with 5000 ppm down spreading with a Hershey-Kiss modulation profile at three different clock frequencies, 540 MHz, 270 MHz and 162 MHz. The measured peak power reduction is about 15.6 dB at 540 MHz with the chip fabricated using a $0.13{\mu}m$ CMOS technology.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.10
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• pp.7-13
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• 2010

A compact phase interpolator (PI) based spread spectrum clock generator (SSCG) for electromagnetic interference (EMI) reduction is presented. The proposed SSCG utilizes a digitally controlled phase interpolation technique to achieve triangular frequency modulation with less design complexity and small power and area overhead. The novel SSCG can generate the system clock with a programmable center-spread spectrum range of up to +/- 2 % at 200 MHz, while maintaining the clock duty cycle ratio without distortions. The PI-based SSCG has been designed and evaluated in 0.18-um 1.8-V CMOS technology, which consumes about 5.0 mW at 200MHz and occupies a chip size of $0.092mm^2$ including a DLL.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1097-1104
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• 2016

The infrared camera is difficult to satisfy the RE-102 specification of Mil-Std-461. Especially, in the case of UAV electronics, shielded cable is not used, so it is difficult to meet the electromagnetic compatibility standard. In the RE-102 test of the IR camera for UAV, radiated noise exceeding 30 dBuV/m was observed in the range of 50 MHz to 200 MHz. As a result of pcb em scan, peak noise which caused by the harmonic frequency of the digital control signal clock was observed. Radiated noise was reduced by up to 22.9 dBuV/m by applying the spread spectrum clock generator(SSCG) with 3 % down spreading method to the camera control clock.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.4
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• pp.425-435
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• 2016

This paper describes a spread-spectrum clock generation method by utilizing a ${\Delta}{\Sigma}$ digital PLL (DPLL) which is solely based on binary phase detection and does not require a linear time-to-digital converter (TDC) or other linear digital-to-time converter (DTC) circuitry. A 1-bit high-order ${\Delta}{\Sigma}$ modulator and a hybrid finite-impulse response (FIR) filter are employed to mitigate the phase-folding problem caused by the nonlinearity of the bang-bang phase detector (BBPD). The ${\Delta}{\Sigma}$ DPLL employs a two-point modulation technique to further enhance linearity at the turning point of a triangular modulation profile. We also show that the two-point modulation is useful for the BBPLL to improve the spread-spectrum performance by suppressing the frequency deviation at the input of the BBPD, thus reducing the peak phase deviation. Based on the proposed architecture, a 3.2 GHz spread-spectrum clock generator (SSCG) is implemented in 65 nm CMOS. Experimental results show that the proposed SSCG achieves peak power reductions of 18.5 dB and 11 dB with 10 kHz and 100 kHz resolution bandwidths respectively, consuming 6.34 mW from a 1 V supply.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.7
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• pp.68-73
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• 2009

This paper describes design and implementation of a spread spectrum clock generator (SSCG) for the DisplayPort. The proposed architecture generates the spread spectrum clock using a sigma-delta fractional-N PLL. The SSCG uses a digital End order MASH 1-1 sigma-delta modulator and a 9bit Up/Dn counter. By using MASH 1-1 sigma-delta modulator, complexity of circuit and chip area can be reduced. The advantage of sigma-delta modulator is the better control over modulation frequency and spread ratio. The SSCG generates dual clock rates which are 270MHz and 162MHz with 0.25% down-spreading and triangular waveform frequency modulation of 33kHz. The peak power reduction is 11.1dBm at 270MHz. The circuit has been designed and fabricated using in 0.18$\mu$m CMOS technology. The chip occupies 0.620mm$\times$0.780mm. The measurement results show that the fabricated chip satisfies the DispalyPort standard.

• Journal of IKEEE
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• v.22 no.2
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• pp.506-509
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• 2018

Recently, number of components and operation frequency rapidly increase in automotive systems. This often leads to EMI (electromagnetic interference) where automotive systems suffer from malfunctions induced by electromagnetic wave. This paper surveys various EMC (electromagnetic compatibility) compliance technologies such as EMI filter, EMI shielding materials, and spread spectrum clock generator. Their pros and cons are also explained.