ISM Band Medium Power Amplifier

With the large-signal model extracted from the InGaP/GaAs HBT with three fingers,a three-stage,class AB power amplifier at ISM band is designed.Through the optimization of the traditional bias network,the gain compression at the low input power level is eliminated successfully.At 3.5V of supply voltage of the power amplifier after optimization exhibits 30dBm of maximum linear output power,43.4% of power added efficiency 109.7mA of a quite low quiescent bias current ,29.1dB of the corresponding gain,and -100dBc of the adjacent channel power rejection (ACPR) at the output power of 30dBm.

Effect of collector bias current on the linearity of common-emitter BJT amplifiers

Using a Volterra series, an explicit formula is derived for the connection between input 3rd-order intercept point and collector bias current （IcQ） in a common-emitter bipolar junction transistor amplifier. The analysis indicates that the larger/CQ is, the more linear the amplifier is. Furthermore, this has been verified by experiment. This study also integrates a method called dynamic bias current for expanding the dynamic range of an LNA （low noise amplifier） as an application of the analysis result obtained above. IMR3 （3rd-order intermodulation rate） is applied to evaluate the LNA＇s performance with and without adopting this method in this study.

Influence of Frequency and Bias Current on Asymmetrical GMI Effect in Co_(71.8)Fe_(4.9)Nb_(0.8)Si_(7.5)B_(15) Amorphous Glass-Covered Wires

The Co71.8Fe4.9Nb0.8Si7.5B15 amorphous glass-covered wires（AGCW）are prepared by the Taylor-Ulitovsky technique.The frequency dependence of asymmetrical giant magneto-impedance（AGMI）effect in amorphous glass-covered wires annealed by 70 mA DC current is here presented.The resistance R and the reactance X have been measured,respectively.The real part R and the imaginary part X of impedance play an important role at high frequency and low frequency,respectively.The influence of DC bias current from Ib=0 mA to Ib=5 mA at 30 MHz on the GMI effect in the glass-covered wires annealed by 70 mA DC current is investigated.The asymmetry becomes the largest around Ib=1 mA,and finally decreases for the larger bias current Ib=5 mA.The maximum ΔZ/Z ratio of 310% is observed at 58 MHz under 1 mA bias current.

Bias Current Influence on the Characteristic of the Magnetic-controlled Switcher Type Fault Current Limiter

A novel magnetic-controlled switcher type fault current limiter （FCL） for high voltage electric network is presented. The current limiting principle of the FCL and the bias current influence on the characteristic of the FCL axe discussed. The experiments on the 220 V/50 A test model show that the FCL can limit the fault current swiftly and effectively. Under the normal state, the bias current adjustment can change the FCL voltage loss; under the fault state, the steady fault current can be easily adjusted to the preset level by bias current regulating. The experimental result is in accordance with the principle analysis and the FCL has the advantages of flexible control strategy and simple and reliable structure.

Low power penalty tunable slow light using vertical-cavity surface-emitting laser amplifier

A tunable slow light of 2.5-Gb/s pseudo-random binary sequence signal using a 1550-nm vertical-cavity surface-emitting laser （VCSEL） is experimentally demonstrated. The influences of the bias current and the gain saturation on the slow light are investigated. With bias current increasing, tunable optical group delay up to 98 ps is obtained at room temperature. Demonstration of the time delay between 16 and 24 ps by signal intensity change is reported. Under an appropriate bias current, by tuning the input signal to track the peak gain wavelength of the VCSEL, slow light of a power penalty as low as 1 dB is achieved. With such a low power penalty, the VCSEL has a great potential application as a compact optical buffer.

Tunable current mirror and its application in LNA

A novel topology of current mirror （CM） with tunable output current is proposed. Two methods for output current tuning are presented. The first one utilizes an analog input voltage for linear current output, and the second one has an N-bit digital input signal for 2N un-continuous current outputs. A linearization method for low noise amplifier （LNA） is proposed and realized with this tunable CM. As the provider of the bias current, the CM has brought the LNA a lower NF （noise figure） and a higher IIP3 （input-referred third-order intercept point） compared with a conventional one. The experimental results show that the LNA achieves 1.47 dB NF and ＋ 19.83 dBm IIP3 at 860 MHz.

A 5 Gb/s low power current-mode transmitter with pre-emphasis for serial links

A multi-standard compatible transmitter with pre-emphasis for high speed serial links is presented. Based on the comparison between voltage mode（VM） and current mode（CM） output driver architectures,a low power CM output driver with reverse scaling and bias current filtering technique is proposed.A 2-tap pre-emphasis filter is used to reduce the intersymbol interference caused by the low-pass channel,and a high speed,low power combined serializer is implemented to convert 10 bit parallel data into a serial data stream.The whole transmitter is fabricated in 65 nm 1.2 V/2.5 V CMOS technology.It provides an eye height greater than 800 mV for data rates of both 2.5 Gb/s and 5 Gb/s.The output root mean square jitter of the transmitter at 5 Gb/s is only 9.94 ps without pre-emphasis.The transmitter consumes 41.2 mA at 5 Gb/s and occupies only 240×140μm^2.