This paper deals with modeling of a monolithic spiral transformer. The transformer is designed an... more This paper deals with modeling of a monolithic spiral transformer. The transformer is designed and fabricated as a symmetrical octagonal spiral structure using two-metal layer process on GaAs substrate for input balun applications of 2 GHz and 5 GHz push-pull power amplifiers. A distributed model of the transformer is developed to fit in wide frequency range with four ports. The model includes the skin effect which describes increase in series resistance with frequency. Six different sets of twoport s-parameters are measured to obtain full characteristics of the four-port transformer while the other two ports are shorted to ground. The model is validated with measurement results in 100 MHz to 6 GHz.
In this paper,,an economic SiGe HBT (hetero- junction bipolar transistor)process using reduced pr... more In this paper,,an economic SiGe HBT (hetero- junction bipolar transistor)process using reduced pressure chemical vapor deposition (RPCVD)process of high throughput and the cheap localized oxidation of silicon (LOCOS)instead of shallow trench,was developed and characterized.To test its feasibility,several low noise amplifiers were designed and fabricated.As well as high cutoff frequency and low noise SiGe HBT devices,the passive elements including planar spiral inductors with only two metal layers,metal-insulator-metal capacitor,three kinds of resistors,and varactor diode were also integrated in the process.With carefully designing of the base profile and adopting finger-type structure,the measured minimum noise figure of 1.5 dB and associated gain of 16 dB at 1.8 GHz consuming the collector current of 4.6 mA at the supply voltage of 2.5V,were obtained in the low noise device.After on-wafer calibration,one of the fabricated low noise amplifiers was measured as 2.5 dB NF and 21 dB ins...
The ESD characteristics of GaAs diode are compared with those of Silicon diode. The ESD diodes ar... more The ESD characteristics of GaAs diode are compared with those of Silicon diode. The ESD diodes are designed and implemented using GaAs HBT technology and 0.25 um CMOS technology. The differences of ESD characteristics between GaAs diode and Silicon diode are investigated, simulated and measured. Because the thermal characteristics of GaAs are different from those of Silicon, the ESD characteristics of GaAs device are different from those of Silicon device.
A K-Band Push-Push VCO MMIC which has small size, high output power and low phase noise is presen... more A K-Band Push-Push VCO MMIC which has small size, high output power and low phase noise is presented. This push-push VCO utilize the embedded frequency doubling mechanism of cross coupled topology. A commercial InGaP/GaAs HBT technology with the f T of 60 GHz and the fMAX of 110 GHz was used for the implementation. The oscillation frequency is from 21.02 GHz to 21.17 GHz. The peak output power of the VCO is 1.7dBm. The phase noise is -110dBc/Hz at 1MHz offset from 21.16 GHz. The chip size is 0.81 0.64 mm2.
A two-stage InGaP/GaAs heterojunction bipolar transistor (HBT) power amplifier is developed for W... more A two-stage InGaP/GaAs heterojunction bipolar transistor (HBT) power amplifier is developed for WLAN 802.11b application. This is integrated with power detector that senses input power of power stage in order to decrease output power loss of detecting. The power amplifier delivers up to 26dBm output power with the maximum power-added efficiency (PAE) of 31% including consumption of the power detector under the supply voltage of 3.3V
This paper proposes a novel analog FIR low p ass filtering scheme. Instead of using one FIR filte... more This paper proposes a novel analog FIR low p ass filtering scheme. Instead of using one FIR filter with large number of coefficients, three cascaded FIR filters with the smaller number of coefficients are used. This scheme is robust against to the coefficient error induced by actual fabrication processes. In addition, the reduced number of switches leads to the small chip area. These allow the small and accurate analog filter to be implemented with deep- submicron digital CMOS process. This filter has a stop band rejection of more than 40 dB, IIP3 of +12.5 dBm, while consuming 1.2 mW power from 1.2 V power supply at sampling frequency of 36 MHz. The core chip area is 0.23 mm 2 .
tr! -n tnh -l E_l\il l. Introduction Quantum well infrared photodetectors (ewlps) utilizing inter... more tr! -n tnh -l E_l\il l. Introduction Quantum well infrared photodetectors (ewlps) utilizing intersubband transitions have been widely used for detecting far-infrared optical signals having wavelengths of 3-5 pm or 8-12 pm within the afrnospheric ffansmission windows. N-QWIPs utilizing the elecfon intersubband nansition have a limitation since absorption of the nonnal-incident light is forbidden. P-QWIPs utilizing hole intersubband transitions can detect the normal-incident light due to the hole-band mixing in strained quantum wells. However, due to the large effective mass of hole, the absorption coefficient and thus the detectivity of the p-QWIPs utilizing the hole intersubband transitions are generally lower than those of QWIPs utilizing the electron intersubband transitions [1]. Chu et al. reported the normal-incident p-i-p eMps having detectivities as high as O.l4 l.07xl0r0 cm'HzrnT[ by using p-doped compressive-strained hGaAs quantum wells [2]. We report a normal-incident Q...
A time-and-frequency hybrid multiplexing technique for a multiple-input multiple-output (MIMO) or... more A time-and-frequency hybrid multiplexing technique for a multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) radar is proposed. Discrete Fourier transform (DFT)-coded OFDM waveforms are introduced, which allow it to be free from range-dependent angle errors. These are readily used to provide both time-domain and frequency-domain multiplexings in the MIMO OFDM radar. The DFT-coded frequency-domain multiplexing shortens the maximum unambiguous range, while the DFT-coded time-domain multiplexing lowers the maximum Doppler ambiguity. A hybrid of both domain multiplexing techniques can mitigate the respective limitations by adaptively selecting the proper DFT matrix size in each multiplexing domain. This allows to solve the intrinsic range and Doppler ambiguity problems of MIMO radars by controlling the hybrid ratio of the two kinds of DFT-code based multiplexing methods. Range-Doppler and range-angle maps of four examples with different hybrid multiplexing ratios are simulated with a MIMO OFDM radar numerical platform. INDEX TERMS Discrete Fourier transform (DFT) code, hybrid multiplexing, multiple-input multipleoutput (MIMO) radar, orthogonal frequency-division multiplexing (OFDM) radar, range and Doppler ambiguities.
Journal of electromagnetic engineering and science
This paper presents a compact K-band Doppler radar sensor for human vital signal detection that u... more This paper presents a compact K-band Doppler radar sensor for human vital signal detection that uses a radar configuration with only single coupler. The proposed radar front-end configuration can reduce the chip size and the additional RF power loss. The radar front-end IC is composed of a Lange coupler, VCO, and single balanced mixer. The oscillation frequency of the VCO is from 27.3 to 27.8 GHz. The phase noise of the VCO is -91.2 dBc/Hz at a 1 MHz offset frequency, and the output power is -4.8 dBm. The conversion gain of the mixer is about 11 dB. The chip size is 0.89×1.47 mm 2 . The compact Ka-band Doppler radar system was developed in order to demonstrate remote human vital signal detection. The radar system consists of a Ka-band Doppler radar module with a 2×2 patch array antenna, baseband signal conditioning block, DAQ system, and signal processing program. The front-end module size is 2.5×2.5 cm 2 . The proposed radar sensor can properly capture a human heartbeat and respiration rate at the distance of 50 cm.
This letter proposes a highly efficient CMOS linear power amplifier (PA) with cascode–cascade con... more This letter proposes a highly efficient CMOS linear power amplifier (PA) with cascode–cascade configuration. The proposed configuration improves AM–PM distortion through a capacitance variation compensation of the input capacitance of a common-gate stage in the main amplifier and a common-source stage of an auxiliary amplifier. In addition, the current consumption in the low-power region is significantly reduced structurally because the auxiliary amplifier is turned off. The PA is implemented in 0.18-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS process with an output combining network in printed circuit board. It provides an average power of 24.5 dBm with a PAE of 45.6% for a long-term-evolution 10-MHz up-link signal with the ACLR<sub>E–UTRA</sub> of −30 dBc at 2 GHz.
Theoretical and experimental studies on photocurrent zue presented in pin GaAs/Ab,SG%,rAs MQW mod... more Theoretical and experimental studies on photocurrent zue presented in pin GaAs/Ab,SG%,rAs MQW modulators and detectors. Field dependent excitonic spectra is calculated to obtain carrier generation and recombination rates using full band mixing effects in the valence band. A tunneling formalism is used to self consistently study the electric field dependence of the electron and hole collection efficiency. At low electric fields and low temperatures the carrier collection efficiency is very poor and we show that the collected photocurrent has a sublinear dependence on the impingii lit intensity. This non-linearity is not due to band filling or exciton screening effects normally observed, but arises from the high recombination rates compared to tunneling rates. At higher electric field the collection efficiency is-100% resulting in a linear response and a negative differential resistance region. Consequences of our studies on intrinsic device speeds are discussed for pi(MQW)-n modulators based on Stark effect.
Extended Abstracts of the 2000 International Conference on Solid State Devices and Materials
An accurate rnethod to determine the thermal resistance (Rtn) of HBT's is proposed and presented ... more An accurate rnethod to determine the thermal resistance (Rtn) of HBT's is proposed and presented in this paper. The principle of this method is based on the current gain (B) decrease of HBT's either from ambient temperature rise or internal DC power dissipation. For
ABSTRACT This paper proposes that transmitter-to-receiver resonator efficiency can be enhanced by... more ABSTRACT This paper proposes that transmitter-to-receiver resonator efficiency can be enhanced by the novel combination of resonator and switching controller at the receiver side. More specifically, the switching controller modulates the load resistance such that the receiver resonance is amplified. This increases the loaded-Q, reflected resistance, and, subsequently, overall efficiency and distance range. The efficiency and distance range are superior than resonator-only receivers, despite of losses from the switching controller itself. This breaks the common routine that typical switching converters only lower the power flow and efficiency when they are inserted in wireless power chain. Moreover, the scheme solves the common problem of load-variation-induced efficiency degradation. More specifically, if the present load value is deviated from optimal point, the proposed controller adjusts the effective load resistance to amplify the reflected resistance. The loaded-Q amplification is easily controlled simply by changing the duty ratio of switching controller. This is more feasible than traditional impedance transformation network whose control requires large array of capacitor-switch matrix or movement of coil position. The efficiencies with and without the switching-controlled resonance amplification are 60.2% and 51.7%, respectively, for a 20-W loading at 15-cm distance for a 20 cm × 16 cm receiver.
JSTS:Journal of Semiconductor Technology and Science, 2008
An X-band MMIC power amplifier for radar application is developed using 0.25-μm gate length GaAs ... more An X-band MMIC power amplifier for radar application is developed using 0.25-μm gate length GaAs pHEMT technology. A bus-bar power combiner at output stage is used to minimize the combiner size and to simplify bias network. The fabricated power amplifier shows 38.75 dBm (7.5 Watt) Psat at 10 GHz. The chip size is 3.5 mm × 3.9 mm.
JSTS:Journal of Semiconductor Technology and Science, 2009
Recent progress in development of CMOS power amplifiers for mobile terminals is reviewed, focusin... more Recent progress in development of CMOS power amplifiers for mobile terminals is reviewed, focusing first on switching mode power amplifiers, which are used for transmitters with constant envelope modulation and polar transmitters. Then, various transmission line transformers are evaluated. Finally, linear power amplifiers, and linearization techniques, are discussed. Although CMOS devices are less linear than other devices, additional functions can be easily integrated with CMOS power amplifiers in the same IC. Therefore, CMOS power amplifiers are expected to have potential applications after various linearity and efficiency enhancement techniques are used.
This paper deals with modeling of a monolithic spiral transformer. The transformer is designed an... more This paper deals with modeling of a monolithic spiral transformer. The transformer is designed and fabricated as a symmetrical octagonal spiral structure using two-metal layer process on GaAs substrate for input balun applications of 2 GHz and 5 GHz push-pull power amplifiers. A distributed model of the transformer is developed to fit in wide frequency range with four ports. The model includes the skin effect which describes increase in series resistance with frequency. Six different sets of twoport s-parameters are measured to obtain full characteristics of the four-port transformer while the other two ports are shorted to ground. The model is validated with measurement results in 100 MHz to 6 GHz.
In this paper,,an economic SiGe HBT (hetero- junction bipolar transistor)process using reduced pr... more In this paper,,an economic SiGe HBT (hetero- junction bipolar transistor)process using reduced pressure chemical vapor deposition (RPCVD)process of high throughput and the cheap localized oxidation of silicon (LOCOS)instead of shallow trench,was developed and characterized.To test its feasibility,several low noise amplifiers were designed and fabricated.As well as high cutoff frequency and low noise SiGe HBT devices,the passive elements including planar spiral inductors with only two metal layers,metal-insulator-metal capacitor,three kinds of resistors,and varactor diode were also integrated in the process.With carefully designing of the base profile and adopting finger-type structure,the measured minimum noise figure of 1.5 dB and associated gain of 16 dB at 1.8 GHz consuming the collector current of 4.6 mA at the supply voltage of 2.5V,were obtained in the low noise device.After on-wafer calibration,one of the fabricated low noise amplifiers was measured as 2.5 dB NF and 21 dB ins...
The ESD characteristics of GaAs diode are compared with those of Silicon diode. The ESD diodes ar... more The ESD characteristics of GaAs diode are compared with those of Silicon diode. The ESD diodes are designed and implemented using GaAs HBT technology and 0.25 um CMOS technology. The differences of ESD characteristics between GaAs diode and Silicon diode are investigated, simulated and measured. Because the thermal characteristics of GaAs are different from those of Silicon, the ESD characteristics of GaAs device are different from those of Silicon device.
A K-Band Push-Push VCO MMIC which has small size, high output power and low phase noise is presen... more A K-Band Push-Push VCO MMIC which has small size, high output power and low phase noise is presented. This push-push VCO utilize the embedded frequency doubling mechanism of cross coupled topology. A commercial InGaP/GaAs HBT technology with the f T of 60 GHz and the fMAX of 110 GHz was used for the implementation. The oscillation frequency is from 21.02 GHz to 21.17 GHz. The peak output power of the VCO is 1.7dBm. The phase noise is -110dBc/Hz at 1MHz offset from 21.16 GHz. The chip size is 0.81 0.64 mm2.
A two-stage InGaP/GaAs heterojunction bipolar transistor (HBT) power amplifier is developed for W... more A two-stage InGaP/GaAs heterojunction bipolar transistor (HBT) power amplifier is developed for WLAN 802.11b application. This is integrated with power detector that senses input power of power stage in order to decrease output power loss of detecting. The power amplifier delivers up to 26dBm output power with the maximum power-added efficiency (PAE) of 31% including consumption of the power detector under the supply voltage of 3.3V
This paper proposes a novel analog FIR low p ass filtering scheme. Instead of using one FIR filte... more This paper proposes a novel analog FIR low p ass filtering scheme. Instead of using one FIR filter with large number of coefficients, three cascaded FIR filters with the smaller number of coefficients are used. This scheme is robust against to the coefficient error induced by actual fabrication processes. In addition, the reduced number of switches leads to the small chip area. These allow the small and accurate analog filter to be implemented with deep- submicron digital CMOS process. This filter has a stop band rejection of more than 40 dB, IIP3 of +12.5 dBm, while consuming 1.2 mW power from 1.2 V power supply at sampling frequency of 36 MHz. The core chip area is 0.23 mm 2 .
tr! -n tnh -l E_l\il l. Introduction Quantum well infrared photodetectors (ewlps) utilizing inter... more tr! -n tnh -l E_l\il l. Introduction Quantum well infrared photodetectors (ewlps) utilizing intersubband transitions have been widely used for detecting far-infrared optical signals having wavelengths of 3-5 pm or 8-12 pm within the afrnospheric ffansmission windows. N-QWIPs utilizing the elecfon intersubband nansition have a limitation since absorption of the nonnal-incident light is forbidden. P-QWIPs utilizing hole intersubband transitions can detect the normal-incident light due to the hole-band mixing in strained quantum wells. However, due to the large effective mass of hole, the absorption coefficient and thus the detectivity of the p-QWIPs utilizing the hole intersubband transitions are generally lower than those of QWIPs utilizing the electron intersubband transitions [1]. Chu et al. reported the normal-incident p-i-p eMps having detectivities as high as O.l4 l.07xl0r0 cm'HzrnT[ by using p-doped compressive-strained hGaAs quantum wells [2]. We report a normal-incident Q...
A time-and-frequency hybrid multiplexing technique for a multiple-input multiple-output (MIMO) or... more A time-and-frequency hybrid multiplexing technique for a multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) radar is proposed. Discrete Fourier transform (DFT)-coded OFDM waveforms are introduced, which allow it to be free from range-dependent angle errors. These are readily used to provide both time-domain and frequency-domain multiplexings in the MIMO OFDM radar. The DFT-coded frequency-domain multiplexing shortens the maximum unambiguous range, while the DFT-coded time-domain multiplexing lowers the maximum Doppler ambiguity. A hybrid of both domain multiplexing techniques can mitigate the respective limitations by adaptively selecting the proper DFT matrix size in each multiplexing domain. This allows to solve the intrinsic range and Doppler ambiguity problems of MIMO radars by controlling the hybrid ratio of the two kinds of DFT-code based multiplexing methods. Range-Doppler and range-angle maps of four examples with different hybrid multiplexing ratios are simulated with a MIMO OFDM radar numerical platform. INDEX TERMS Discrete Fourier transform (DFT) code, hybrid multiplexing, multiple-input multipleoutput (MIMO) radar, orthogonal frequency-division multiplexing (OFDM) radar, range and Doppler ambiguities.
Journal of electromagnetic engineering and science
This paper presents a compact K-band Doppler radar sensor for human vital signal detection that u... more This paper presents a compact K-band Doppler radar sensor for human vital signal detection that uses a radar configuration with only single coupler. The proposed radar front-end configuration can reduce the chip size and the additional RF power loss. The radar front-end IC is composed of a Lange coupler, VCO, and single balanced mixer. The oscillation frequency of the VCO is from 27.3 to 27.8 GHz. The phase noise of the VCO is -91.2 dBc/Hz at a 1 MHz offset frequency, and the output power is -4.8 dBm. The conversion gain of the mixer is about 11 dB. The chip size is 0.89×1.47 mm 2 . The compact Ka-band Doppler radar system was developed in order to demonstrate remote human vital signal detection. The radar system consists of a Ka-band Doppler radar module with a 2×2 patch array antenna, baseband signal conditioning block, DAQ system, and signal processing program. The front-end module size is 2.5×2.5 cm 2 . The proposed radar sensor can properly capture a human heartbeat and respiration rate at the distance of 50 cm.
This letter proposes a highly efficient CMOS linear power amplifier (PA) with cascode–cascade con... more This letter proposes a highly efficient CMOS linear power amplifier (PA) with cascode–cascade configuration. The proposed configuration improves AM–PM distortion through a capacitance variation compensation of the input capacitance of a common-gate stage in the main amplifier and a common-source stage of an auxiliary amplifier. In addition, the current consumption in the low-power region is significantly reduced structurally because the auxiliary amplifier is turned off. The PA is implemented in 0.18-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS process with an output combining network in printed circuit board. It provides an average power of 24.5 dBm with a PAE of 45.6% for a long-term-evolution 10-MHz up-link signal with the ACLR<sub>E–UTRA</sub> of −30 dBc at 2 GHz.
Theoretical and experimental studies on photocurrent zue presented in pin GaAs/Ab,SG%,rAs MQW mod... more Theoretical and experimental studies on photocurrent zue presented in pin GaAs/Ab,SG%,rAs MQW modulators and detectors. Field dependent excitonic spectra is calculated to obtain carrier generation and recombination rates using full band mixing effects in the valence band. A tunneling formalism is used to self consistently study the electric field dependence of the electron and hole collection efficiency. At low electric fields and low temperatures the carrier collection efficiency is very poor and we show that the collected photocurrent has a sublinear dependence on the impingii lit intensity. This non-linearity is not due to band filling or exciton screening effects normally observed, but arises from the high recombination rates compared to tunneling rates. At higher electric field the collection efficiency is-100% resulting in a linear response and a negative differential resistance region. Consequences of our studies on intrinsic device speeds are discussed for pi(MQW)-n modulators based on Stark effect.
Extended Abstracts of the 2000 International Conference on Solid State Devices and Materials
An accurate rnethod to determine the thermal resistance (Rtn) of HBT's is proposed and presented ... more An accurate rnethod to determine the thermal resistance (Rtn) of HBT's is proposed and presented in this paper. The principle of this method is based on the current gain (B) decrease of HBT's either from ambient temperature rise or internal DC power dissipation. For
ABSTRACT This paper proposes that transmitter-to-receiver resonator efficiency can be enhanced by... more ABSTRACT This paper proposes that transmitter-to-receiver resonator efficiency can be enhanced by the novel combination of resonator and switching controller at the receiver side. More specifically, the switching controller modulates the load resistance such that the receiver resonance is amplified. This increases the loaded-Q, reflected resistance, and, subsequently, overall efficiency and distance range. The efficiency and distance range are superior than resonator-only receivers, despite of losses from the switching controller itself. This breaks the common routine that typical switching converters only lower the power flow and efficiency when they are inserted in wireless power chain. Moreover, the scheme solves the common problem of load-variation-induced efficiency degradation. More specifically, if the present load value is deviated from optimal point, the proposed controller adjusts the effective load resistance to amplify the reflected resistance. The loaded-Q amplification is easily controlled simply by changing the duty ratio of switching controller. This is more feasible than traditional impedance transformation network whose control requires large array of capacitor-switch matrix or movement of coil position. The efficiencies with and without the switching-controlled resonance amplification are 60.2% and 51.7%, respectively, for a 20-W loading at 15-cm distance for a 20 cm × 16 cm receiver.
JSTS:Journal of Semiconductor Technology and Science, 2008
An X-band MMIC power amplifier for radar application is developed using 0.25-μm gate length GaAs ... more An X-band MMIC power amplifier for radar application is developed using 0.25-μm gate length GaAs pHEMT technology. A bus-bar power combiner at output stage is used to minimize the combiner size and to simplify bias network. The fabricated power amplifier shows 38.75 dBm (7.5 Watt) Psat at 10 GHz. The chip size is 3.5 mm × 3.9 mm.
JSTS:Journal of Semiconductor Technology and Science, 2009
Recent progress in development of CMOS power amplifiers for mobile terminals is reviewed, focusin... more Recent progress in development of CMOS power amplifiers for mobile terminals is reviewed, focusing first on switching mode power amplifiers, which are used for transmitters with constant envelope modulation and polar transmitters. Then, various transmission line transformers are evaluated. Finally, linear power amplifiers, and linearization techniques, are discussed. Although CMOS devices are less linear than other devices, additional functions can be easily integrated with CMOS power amplifiers in the same IC. Therefore, CMOS power amplifiers are expected to have potential applications after various linearity and efficiency enhancement techniques are used.
Uploads
Papers by Songcheol Hong