30 dB optical net gain at 1.543 mu m in Er/sup 3+/ doped fluoride fibre pumped around 1.48 mu m

A 30 dB optical net gain and 12 dBm maximum output power for -1 dBm signal input have been measured at a signal wavelength of 1.54 mu m with an erbium doped ZBLAN fibre pumped at 1.47-1.48 mu m. The results confirm the great potential of ZBLAN fibres for hosting rare earth ions to generate optical amplification. The discussion points out the parameters to be studied to improve the fibre amplifier performance.<>     

Self-heating and trapping effects on the RF performance of GaN MESFETs

RF power performances of GaN MESFETs incorporating self-heating and trapping effects are reported. A physics-based large-signal model is used, which includes temperature dependences of transport and trapping parameters. Current collapse and dc-to-RF dispersion of output resistance and transconductance due to traps have been accounted for in the formulation. Calculated dc and pulsed I-V characteristics are in excellent agreement with the measured data. At 2 GHz, calculated maximum output power of a 0.3 /spl mu/m/spl times/100 /spl mu/m GaN MESFET is 22.8 dBm at the power gain of 6.1 dB and power-added efficiency of 28.5% are in excellent agreement with the corresponding measured values of 23 dBm, 5.8 dB, and 27.5%, respectively. Better thermal stability is observed for longer gate-length devices due to lower dissipation power density. At 2 GHz, gain compressions due to self-heating are 2.2, 1.9, and 0.75 dB for 0.30 /spl mu/m/spl times/100 /spl mu/m, 0.50 /spl mu/m/spl times/100 /spl mu/m, and 0.75 /spl mu/m/spl times/100 /spl mu/m GaN MESFETs, respectively. Significant increase in gain compression due to thermal effects is reported at elevated frequencies. At 2-GHz and 10-dBm output power, calculated third-order intermodulations (IM3s) of 0.30 /spl mu/m/spl times/100 /spl mu/m, 0.50 /spl mu/m/spl times/100 /spl mu/m, and 0.75 /spl mu/m/spl times/100 /spl mu/m GaN MESFETs are -61, -54, and - 45 dBc, respectively. For the same devices, the IM3 increases by 9, 6, and 3 dBc due to self-heating effects, respectively. Due to self-heating effects, the output referred third-order intercept point decreases by 4 dBm in a 0.30 /spl mu/m/spl times/100 /spl mu/m device.     

A fully monolithic 260-/spl mu/W, 1-GHz subthreshold low noise amplifier

A micro-power complementary metal oxide semiconductor (CMOS) low-noise amplifier (LNA) is presented based on subthreshold MOS operation in the GHz range. The LNA is fabricated in an 0.18-/spl mu/m CMOS process and has a gain of 13.6 dB at 1 GHz while drawing 260 /spl mu/A from a 1-V supply. An unrestrained bias technique, that automatically increases bias currents at high input power levels, is used to raise the input P1dB to -0.2 dBm. The LNA has a measured noise figure of 4.6 dB and an IIP3 of 7.2 dBm.     

Analysis of partially depleted absorber waveguide photodiodes

This paper presents the analysis and characterization of partially depleted absorber (PDA) photodiodes. Coupling to these photodiodes is achieved through a planar short multimode waveguide (PSMW) structure. Electric transport in the PDA structure has been investigated and an equivalent electric circuit was developed. Measurements on 5/spl times/20 /spl mu/m/sup 2/ PSMW PDA photodiodes have shown 0.80 A/W responsivity with a fiber mode diameter as high as 6 /spl mu/m. The transverse electric/transverse magnetic polarization dependence was <0.5/spl plusmn/0.3 dB with -1-dB input coupling tolerances as high as /spl plusmn/2.0 and /spl plusmn/1.3 /spl mu/m for horizontal and vertical directions. The -3-dB bandwidth was 50 GHz, and the -1-dB compression current at 40 GHz was 17 mA corresponding to +4.5 dBm radio frequency (RF) power. Compared to similar evanescently coupled p-i-n photodiodes, the saturation current has been significantly improved while maintaining comparable bandwidth and high responsivity.     

Nonlinear analysis of GaN MESFETs with Volterra series using large-signal models including trapping effects

Nonlinearities in GaN MESFETs are reported using a large-signal physics-based model. The model accounts for the observed current collapse to determine the frequency dispersion of output resistance and transconductance. Calculated f/sub T/ and f/sub max/ of a 0.8 /spl mu/m/spl times/150 /spl mu/m GaN MESFET are 6.5 and 13 GHz, respectively, which are in close agreement with their measured values of 6 and 14 GHz, respectively. A Volterra-series technique is used to calculate size and frequency-dependent nonlinearities. For a 1.5 /spl mu/m/spl times/150 /spl mu/m FET operating at 1 GHz, the 1 dB compression point and output-referred third-order intercept point are 16.3 and 22.2 dBm, respectively. At the same frequency, the corresponding quantities are 19.6 and 30.5 dBm for a. 0.6 /spl mu/m/spl times/150 /spl mu/m FET. Similar improvements in third-order intermodulation for shorter gatelength devices are observed.     

A fully integrated 5.3-GHz 2.4-V 0.3-W SiGe bipolar power amplifier with 50-/spl Omega/ output

A radio frequency power amplifier for 4.8-5.7 GHz has been realized in a 0.35-/spl mu/m SiGe bipolar technology. The balanced two-stage push-pull power amplifier uses two on-chip transformers as input-balun and for interstage matching. Further, it uses three coils for the integrated LC-output balun and the RF choke. Thus, the power amplifier does not require any external components. At 1.0-V, 1.5-V, and 2.4-V supply voltages, output powers of 17.7 dBm, 21.6 dBm, and 25 dBm are achieved at 5.3 GHz. The respective power-added efficiencies (PAE) are 15%, 22%, and 24%. The small-signal gain is 26 dB. The output 1-dB compression point at 2.4 V is 22 dBm with a PAE of 14%.     

Two-section distributed feedback lasers for incoherent frequency-shift-keying transmission systems

Fabrication and performance characteristics of two-section distributed feedback lasers operating at 1.55 mu m are presented. Using this type of laser, a 622 Mbit/s incoherent frequency-shift-keying system over a 40 km fibre has been demonstrated with a receiver sensitivity of -41 dBm at a BER of 10/sup -9/.<>     

A dual-band 5.15-5.35-GHz, 2.4-2.5-GHz 0.18-/spl mu/m CMOS transceiver for 802.11a/b/g wireless LAN

A single-chip dual-band 5.15-5.35-GHz and 2.4-2.5-GHz zero-IF transceiver for IEEE 802.11a/b/g WLAN systems is fabricated on a 0.18-/spl mu/m CMOS technology. It utilizes an innovative architecture including feedback paths that enable digital calibration to help eliminate analog circuit imperfections such as transmit and receive I/Q mismatch. The dual-band receive paths feature a 4.8-dB (3.5-dB) noise figure at 5.25 GHz (2.45 GHz). The corresponding sensitivity at 54 Mb/s operation is -76 dBm for 802.11a and -77 dBm for 802.11g, both referred at the input of the chip. The transmit chain achieves output 1-dB compression at 6 dBm (9 dBm) at 5 GHz (2.4 GHz) operation. Digital calibration helps achieve an error vector magnitude (EVM) of -33 dB (-31 dB) at 5 GHz (2.4 GHz) while transmitting -4 dBm at 54Mb/s. The die size is 19.3 mm/sup 2/ and the power consumption is 260 mW for the receiver and 320 mW (270 mW) for the transmitter at 5 GHz (2.4 GHz) operation.     

5.2 GHz SiGe HBT upconverter using active-inductor LC current mirror

A compact 5.2 GHz upconversion micromixer using the 0.35 /spl mu/m SiGe HBT technology is demonstrated. A bandpass and area-saving LC current mirror using the active inductor is incorporated to increase the conversion gain. The demonstrated upconverter has conversion gain of -3.5 dB, OP/sub 1dB/ of -10 dBm, and OIP/sub 3/ of 0 dBm.     

A V-band up-converting InP HEMT active mixer with low LO-power requirements

In this letter, we present a monolithically integrated up-converting active mixer that shifts a signal in the 16 GHz range up to the V-band using a 48 GHz local oscillator (LO) signal. The circuit was realized with the 0.2 /spl mu/m InP HEMT in-house process of the Swiss Federal Institute of Technology in Zurich using coplanar-waveguide technology. Measurements of the fabricated circuit show a peak conversion gain of 1 dB at 64.5 GHz for -1.7 dBm LO power, LO suppression better than 30 dB and input third-order intercept point of -1.6 dBm. This mixer will be employed in the signal up-conversion path of a 60 GHz transceiver for indoor wireless LANs.     

Ultra-broadband 20.5-31 GHz monolithically-integrated CMOS power amplifier

A fully monolithically-integrated power amplifier with a bandwidth (-3 dB) from 20.5 to 31 GHz was realised in a 0.13 /spl mu/m standard CMOS technology. A maximum power added efficiency of 13% with a corresponding output power of 13 dBm was achieved at 25.7 GHz with 1.5 V supply voltage.     

Monolithic integrated wavelength duplexer-receiver on InP

The monolithic integration of a detector stage comprising a photodiode and a field-effect transistor with a load resistor and a wavelength duplexer, realized in the GaInAsP/InP material system, is described. Design considerations, in particular for the wavelength duplexer, but for the complete chip as well, are reported, and details related to the realization of the device are given. Chips were mounted into housings and operated in a 1.3- mu m/1.55- mu m bidirectional transmission link. At 576 Mb/s and 10/sup -9/ bit error rate, the sensitivity of the module is -21 dBm, the intrinsic sensitivity of the receiver is -28 dBm, and the gain-bandwidth product for the lowest noise bias conditions is 3.8 GHz.<>     

Noise characteristics of Pr/sup 3+/-doped fluoride fibre amplifier

The noise characteristics of a Pr/sup 3+/-doped fluoride fibre amplifier (PDFFA) are reported for the first time. Using an amplifier with a 20 dB gain, a noise figure of 3.2 dB is obtained at a wavelength of 1.31 mu m at an amplified output signal power between -18 and -2 dBm. However, it is observed that the noise figure increases when the signal wavelength is above 1.32 mu m.<>     

Highly integrated 60 GHz transmitter and receiver MMICs in a GaAs pHEMT technology

Highly integrated transmitter and receiver MMICs have been designed in a commercial 0.15 /spl mu/m, 88 GHz f/sub T//183 GHz f/sub MAX/ GaAs pHEMT MMIC process and characterized on both chip and system level. These chips show the highest level of integration yet presented in the 60 GHz band and are true multipurpose front-end designs. The system operates with an LO signal in the range 7-8 GHz. This LO signal is multiplied in an integrated multiply-by-eight (X8) LO chain, resulting in an IF center frequency of 2.5 GHz. Although the chips are inherently multipurpose designs, they are especially suitable for high-speed wireless data transmission due to their very broadband IF characteristics. The single-chip transmitter MMIC consists of a balanced resistive mixer with an integrated ultra-wideband IF balun, a three-stage power amplifier, and the X8 LO chain. The X8 is a multifunction design by itself consisting of a quadrupler, a feedback amplifier, a doubler, and a buffer amplifier. The transmitter chip delivers 3.7/spl plusmn/1.5 dBm over the RF frequency range of 54-61 GHz with a peak output power of 5.2 dBm at 57 GHz. The single-chip receiver MMIC contains a three-stage low-noise amplifier, an image reject mixer with an integrated ultra-wideband IF hybrid and the same X8 as used in the transmitter chip. The receiver chip has 7.1/spl plusmn/1.5 dB gain between 55 and 63 GHz, more than 20 dB of image rejection ratio between 59.5 and 64.5 GHz, 10.5 dB of noise figure, and -11 dBm of input-referred third-order intercept point (IIP3).     

192 GHz push-push VCO in 0.13 /spl mu/m CMOS

A 192 GHz cross-coupled push-push voltage controlled oscillator (VCO) is fabricated using the UMC 0.13 /spl mu/m CMOS logic process. The VCO can be tuned from 191.4 to 192.7 GHz. The VCO provides output power of /spl sim/-20 dBm and phase noise of /spl sim/-100 dBc/Hz at 10 MHz offset, while consuming 11 mA from a 1.5 V supply.     

Maximum single frequency input power in a long optical fibre determined by stimulated Brillouin scattering

The experimental results of stimulated Brilloum scattering in about a 4 km fibre are reported. The pumping wavelength is 0.71 ?m. The Brilloum shift frequency was measured to be about 25 GHz. The transmitted power was found to be constant, when the input power exceeds about 14.8 dBm. The saturated transmitted power was 0.5 dBm, which corresponded with the output when 14.8 dBm input power was coupled and only linear fibre loss (about 4.0 dB/km) was assumed.     

Narrow-linewidth strained-layer 1.5 mu m multiquantum well distributed feedback lasers

The performance characteristics of narrow-linewidth strained-layer 1.5 mu m multi-quantum-well distributed feedback (MQW-DFB) lasers are presented. Measured linewidth as low as 3.5 MHz has been observed for one of the 250 mu m long devices at 14.4 mW output. Under 1.7 Gbit/s 1.0, 1.0, . . . pattern signal modulation, the lasers have 20 dB down full width chirp in the range of 5-6 AA for the off state at 0.8 I/sub th/. The chirp widths are about half of those of bulk-active DFB lasers. A 1.7 Gbit/s amplitude-shift-keying transmission experiment using one of the low-chirp lasers has been demonstrated. The transmission over 60 km of standard fibre only result in a 0.8 dB dispersion power penalty and has a receiver sensitivity of -36.2 dBm at BER=10/sup -9/.<>     

50 GHz InGaAs edge-coupled PIN photodetector

An edge-coupled PIN photodetector with an InGaAs absorber layer has been designed and fabricated. Values of bandwidth at 1530 nm, with and without bias, have been measured as 50 GHz and 20 GHz, respectively. The external quantum efficiency is as high as 40% using a standard 12 mu m radius lens-ended single-mode fibre.<>     

10 Gbit/s optical front end using Si-bipolar preamplifier IC, flipchip APD, and slant-end fibre

An optical front end for a 10 Gbit/s optical receiver has been fabricated that features a 10 GHz Si preamplifier IC, a flipchip APD with an 80 GHz gain-bandwidth product, and slant-end fibre optical coupling. Hybrid construction consisting of a flipchip APD mounted directly on the preamplifier chip minimises interconnect parasitics, and slant-end fibre optical coupling simplifies flat-package assembly of chip and fibre. An optical sensitivity of -23 dBm was achieved.<>     

15-GHz fully integrated nMOS switches in a 0.13-/spl mu/m CMOS process

Two fully integrated nMOS switches have been demonstrated at 15 GHz in a 0.13-/spl mu/m CMOS foundry process. One incorporates on-chip LC impedance transformation networks (ITNs) while the second one does not. The switches with and without ITNs achieve the same 1.8-dB insertion loss at 15 GHz, but 21.5 and 15 dBm input P/sub 1dB/, respectively. The degradation of insertion loss due to use of ITNs is compensated by reducing the mismatch loss caused by the bond pad parasitics. The switch without ITNs is suitable for 3.1-10.6 GHz ultra-wide-band (UWB) applications. The switch with ITNs has /spl sim/5 dB worse isolation than the switch without. The difference is due to the larger transistor size of the switch with ITNs, which introduces lower parasitic impedance path between Tx/Rx ports and antenna port.