Browsing by Author "Liang, V"

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Hot-carrier induced degradations on RF power characteristics of SiGe heterojunction bipolar transistors
(2005-06-01)
Huang, SY
;
Chen, KM
;
Huang, GW
;
Liang, V
;
Tseng, HC
Hot-carrier (HC) effects on high-frequency and RF power characteristics of Si/SiGe HBTs are investigated in this paper. By using the two-tone load-pull measurement, we find that not only the cutoff frequency, but also the output power performances of Si/SiGe HBTs are suffered by the HC stress. In this work, S-parameters and intrinsic elements of an equivalent hybrid-pi model were used to validate the HC effects on high-frequency characteristics. With different bias conditions, the degradations of cutoff frequency, power gain, and linearity are found to be worse under constant base-current measurement than that under constant collector-current measurement. The HC-induced degradations on the current gain, transconductance, and ideality-factor of base and collector currents are analyzed to explain the experimental observations.
Impact of hot carrier stress on RF power characteristics of MOSFETs
(2005)
Huang, SY
;
Chen, KM
;
Huang, GW
;
Yang, DY
;
Chang, CY
This paper investigates hot-carrier (HQ effects on the RF power and linearity characteristics of MOS transistors using load-pull measurement. We found that the RF power characteristics are affected by the HC stress, and the linearity of MOS transistors is clearly degraded after HC stress at constant gate voltage measurement. However, at high gate voltage bias, the HC-induced power degradation is much reduced compared with that under low gate voltage regimes. In addition, HC effects on linearity can be softened by biasing the transistor at constant drain currents. These experimental observations can be explained by the change of threshold voltage, transconductance, subthreshold swing, and mobility degradation coefficient under HC stress.
Linearity and power characteristics of SiGeHBTs at high temperatures for RF applications
(2005-07-01)
Chen, KM
;
Peng, AS
;
Huang, GW
;
Chen, HY
;
Huang, SY
In this paper, the power gain, power-added efficiency (PAE) and linearity of power SiGe heterojunction-bipolar transistors at various temperatures have been presented. The power characteristics were measured using a two-tone load-pull system. For transistors biased with fixed base voltage, the small-signal power gain and PAE of the devices increase with increasing temperature at low base voltages, while they decrease at high base voltages. Besides, the linearity is improved at high temperature for all voltage biases. However, for devices with fixed collector current, the small-signal power gain, PAE, and linearity are nearly unchanged with temperature. The temperature dependence of power and linearity characteristics can be understood by analyzing the cutoff frequency, the collector current, Kirk effect and nonlinearities of transconductance at different temperatures.
Low RF loss and noise of transmission lines on Si substrates using an improved ion implantation process
(2003)
Chan, KT
;
Chin, A
;
McAlister, SP
;
Chang, CY
;
Tseng, C
Very low power loss less than or equal to 0.6 dB at 110 GHz and noise of < 0.25 dB at 18 GHz have been measured on transmission lines fabricated on Si substrates and implanted with proton. In contrast, much worse power loss of 5 dB and higher noise of 2.5 dB were measured without implantation. This large improvement arises from the high resistivity by proton implantation, which was also done after forming the transmission lines and at a reduced energy of similar to 4 MeV for easier process integration into current VLSI technology.
Optimized noise and consistent RF model for 0.18 mu m MOSFETs
(2003)
Huang, CH
;
Li, HY
;
Chin, A
;
Liang, V
;
Chien, SC
Strong dependence of finger number on minimum noise figure (NFmin) is observed in 0.18 mum MOSFETs. A lowest NFmin of 0.93 dB is measured at 5.8 GHz using 50 fingers but increases as either increasing or decreasing finger number. We have used a self-consistent S-parameter and NFmin model to analysis this abnormal finger number dependence, and the reason is due to the combined effect of reducing gate resistance and increasing substrate loss as increasing finger number.
RF passive devices on Si with excellent performance close to ideal devices designed by electro-magnetic simulation
(2003)
Chin, A
;
Chan, KT
;
Huang, CH
;
Chen, C
;
Liang, V
High quality RF inductors, very low loss and noise CPW and microstrip lines, advanced broad and narrow band filters, and ring resonators have been achieved on Si substrates, using an optimized proton implantation process. The RF performance up to 100 GHz is close to that for ideal devices designed by EM simulation for lossless substrates.
The minimum noise figure and mechanism as scaling RF MOSFETs from 0.18 to 0.13 mu m technology nodes
(2003)
Huang, CH
;
Chan, KT
;
Chen, CY
;
Chin, A
;
Huang, GW
As scaling down the RF MOSFET from 0.18 to 0.13 mum technology nodes, the f(T) increases but the NFmin becomes worse by increasing similar to0.2 dB. A small NFmin of 0.93 dB is measured at 5.8 GHz in 0.18 mum MOSFET using 50 fingers but increases as either increasing or decreasing finger number. This abnormal dependence and higher noise at 0.13 mum is accurately analyzed by equivalent circuit model and due to the combined gate resistance and substrate effect.