Gain characteristics of CO2laser amplifiers at 10.6 microns

Single-pass gain at 10.6 microns has been studied parametrically in nonflowing CO2or buffered CO2amplifying media. The gain profile across the amplifier diameter and integrated gain both were determined. Parameters varied included buffer gas type, mixture ratio, gas pressure, amplifier bore, discharge current, and wall temperature. Tube bores of 12, 22, and 34 mm and buffer gases of H2, He, Ne, A, and N2were studied. Optimum gain is relatively independent of current density, but decreases with increasing wall temperature. The pressure-diameter relationshipP_{CO_{2}} cdot D sim 4torr-cm was found to hold for CO2, CO2:He, and CO2:N2amplifying media at optimum gain. The gain depends strongly on the CO2partial pressure and is relatively insensitive to the buffer gas pressure except for the case of H2. The maximum gain decreased slowly with increasing amplifier diameter. The highest gain, 1.7 dB/meter, was achieved with a helium buffer gas in amplifiers with a diameter of 22 mm or less. No gain saturation was detected for a 30-dB range of input signal power, from a milliwatt to a few watts. Spectrograms showed that the principal spontaneous emission from CO2:He amplifiers in the 2000-7000-Å range consisted of CO bands; no CO2bands or He line spectra were observed.     

Small-signal gain of a CO2laser amplifier utilizing a white optical reflector design

A small-signal gain of 39 dB in a nonresonant multi-path CO2laser amplifier with a discharge length of 65 cm is reported. The multipath system employed is a modified White optical reflector design. An unsaturated gain of 39 dB was observed for signals smaller than 10^-5watt. No noise component, due to the amplifier, was detected for signals as small as5 times 10^{-8}watt.     

Effects of gas flow on gain of 10.6 micron CO2laser amplifiers

Small-signal gain of flowing gas CO2laser amplifiers at 10.6 microns has been optimized for media including pure CO2CO2: N2, CO2: He, CO2: CO, CO2: O2, CO2: N2: He, CO2: CO : He, and CO2: CO : N2. Optimum gain of all flowing gas systems studied increases monotonically with increasing gas flow rate. In the low CO2flow rate region, 10 < RCO2: < 50 cm³/min, gas flow enhances the gain most for systems containing N2. Results provide strong evidence that the rapid increase in gain with flow rate in CO2: N2mixtures is due to removal by convection of the dissociated product CO. For 50 < RCO2< 200 cm³/min, a slow linear increase in gain of all gas mixtures with increasing flow rate occurs and is attributed to the cooling of gas temprature by convection. A stronger dependence of gainGon amplifier boreD, viz.,G propto I/D, was obtained for flowing gas media relative to that previously observed for nonflowing gas mixtures which is consistent with the proposed mechanism of gas cooling by convection. Highest gain values obtained were 7.8 and 6.2 dB/m with the flowing gas mixtures CO2: N2: He and CO2: CO : He, respectively, in a 12 mm bore water-cooled amplifier tube. Similarities between CO2: N2and CO2: CO systems suggest that pumping of the CO2laser by resonant transfer from CO* (upsilon = 1) can be significant.     

A 3 V 10 MHz pseudo-differential SC bandpass filter using gainenhancement replica amplifier

This paper describes the design strategy and implementation of a high frequency low voltage pseudo-differential SC filter which use opamps with gain enhancement replica amplifier. Experimental results of a biquad SC bandpass with a center frequency of 10 MHz and a Q of 10 are presented. The realized opamp has an open-loop unity-gain bandwidth of 850 MHz, a phase margin of about 62°, and a dc gain of 50 dB. The prototype filter dissipates 23 mW from a 3 V supply and occupies 0.3 mm ² in a 0.8 μm N-well single-poly, double-metal CMOS process     

Design of a low noise distributed amplifier with adjustable gain control in 0.15μm GaAs PHEMT

正A low noise distributed amplifier consisting of 9 gain cells is presented.The chip is fabricated with 0.15-μm GaAs pseudomorphic high electron mobility transistor(PHEMT) technology from Win Semiconductor of Taiwan.A special optional gate bias technique is introduced to allow an adjustable gain control range of 10 dB.A novel cascode structure is adopted to extend the output voltage and bandwidth.The measurement results show that the amplifier gives an average gain of 15 dB with a gain flatness of±1 dB in the 2-20 GHz band.The noise figure is between 2 and 4.1 dB during the band from 2 to 20 GHz.The amplifier also provides 13.8 dBm of output power at a 1 dB gain compression point and 10.5 dBm of input third order intercept point(IIP3),which demonstrates the excellent performance of linearity.The power consumption is 300 mW with a supply of 5 V,and the chip area is 2.36×1.01 mm~2.     

High‐Gain Wideband CMOS Low Noise Amplifier with Two‐Stage Cascode and Simplified Chebyshev Filter

An ultra‐wideband low‐noise amplifier is proposed with operation up to 8.2 GHz. The amplifier is fabricated with a 0.18‐μm CMOS process and adopts a two‐stage cascode architecture and a simplified Chebyshev filter for high gain, wide band, input‐impedance matching, and low noise. The gain of 19.2 dB and minimum noise figure of 3.3 dB are measured over 3.4 to 8.2 GHz while consuming 17.3 mW of power. The Proposed UWB LNA achieves a measured power‐gain bandwidth product of 399.4 GHz.     

A 1-GHz bipolar class-AB operational amplifier with multipathnested Miller compensation for 76-dB gain

A 1-GHz operational amplifier with a gain of 76 dB while driving a 50-Ω load is presented. The equivalent input noise voltage is as low as 1.2 nV/√Hz. This combination of extremely high bandwidth, high gain, and low noise is the result of a three-stage all-n-p-n topology combined with a multipath nested Miller compensation. Using 10-GHz f_T n-p-n transistors, the realizable bandwidth could be of the order of 2-3 GHz. However, bond-wire inductances restrict the useful bandwidth to 1 GHz. The amplifier occupies an active area of 0.26 mm² and has been realized in the bipolar part of a 1-μm BiCMOS process     

A plastic package GaAs MESFET 5.8-GHz receiver front-end withon-chip matching for ETC system

A plastic package GaAs MESFET receiver front-end monolithic microwave integrated circuit operating at 5.8 GHz is presented in this paper. It has a two-stage low-noise amplifier followed by a dual-gate mixer. Operating at 3 V and 8.3 mA, a conversion gain of 20.4 dB, noise figure of 4.1 dB, and high port-to-port isolations have been achieved. Total chip size of 1.0×0.9 mm² has been achieved through on-chip matching for both RF and local-oscillator ports and the use of simple two-element matching networks for all interstage matching. The 3-dB bandwidth of conversion gain is 1 GHz     

A monolithic three-stage 2-8-GHz feedback amplifier

A monolithic three-stage resistive-feedback amplifier has been developed for the 2-8-GHz band. This amplifier uses a novel approach which incorporates three stages with varying FET gate widths. The measured gain is 19 ± 1 dB and the VSWR is 2.3:1 in this band. The amplifier chip has a noise figure of ∼6 dB over the bandwidth. The chip size is less than 2.0 × 1.6 mm²and includes the bias circuitry. The amplifier also has AGC capability with more than 20 dB of gain control.     

Bandwidth enhancement for transimpedance amplifiers

A technique for bandwidth enhancement of a given amplifier is presented. Adding several interstage passive matching networks enables the control of transfer function and frequency response behavior. Parasitic capacitances of cascaded gain stages are isolated from each other and absorbed into passive networks. A simplified design procedure, using well-known low-pass filter component values, is introduced. To demonstrate the feasibility of the method, a CMOS transimpedance amplifier (TIA) is implemented in a 0.18-/spl mu/m BiCMOS technology. It achieves 3 dB bandwidth of 9.2 GHz in the presence of a 0.5-pF photodiode capacitance. This corresponds to a bandwidth enhancement ratio of 2.4 over the amplifier without the additional passive networks. The transresistance gain is 54 dB/spl Omega/, while drawing 55 mA from a 2.5-V supply. The input sensitivity of the TIA is -18 dBm for a bit error rate of 10/sup -12/.     

S-band single-stage EDFA with 25-dB gain using distributed ASE suppression

We propose a novel compact design for a single-stage S-band erbium-doped fiber amplifier, wherein distributed suppression of C-band amplified spontaneous emission is provided by optimized bend loss in a coaxial core fiber. Simulations show that /spl sim/25-dB unsaturated gain over 30-nm bandwidth (1495-1525) nm is achievable with the designed module, using a nominal pump power of 500 mW. The noise figure of the amplifier varies between 4.5 and 8 dB from 1495 to 1525 nm. By proper designing, we have also ensured that the gain ripple over the entire 30-nm bandwidth is 相似文献   

Integrated Amplifier Circuits for 60 GHz Broadband Telecommunication

Wide frequency bandwidth has been internationally allocated for unlicensed operation around the oxygen absorption frequency at 60 GHz. A power amplifier and a low noise amplifier are presented as building blocks for a T/R-unit at this frequency. The fabrication technology was a commercially available 0.15 m gallium arsenide (GaAs) process featuring pseudomorphic high electron mobility transistors (PHEMT). Using on-wafer tests, we measured a gain of 13.4 dB and a +17 dBm output compression point for the power amplifier at 60 GHz centre frequency when the MMIC was biased to 3 volts V_dd. At the same frequency, the low noise amplifier exhibited 24 dB of gain with a 3.5 dB noise figure. The AM/AM and AM/PM characteristics of the power amplifier chip were obtained from the large-signal S-parameter measurement data. Furthermore, the power amplifier was assembled in a split block package, which had a WR-15 waveguide interface in input and output. The measured results show a 12.5 dB small-signal gain and better than 8 dB return losses in input and output for the packaged power amplifier.     

An oversampling converter for strain gauge transducers

An oversampling converter that directly digitizes low-level strain gauge transducer outputs is presented. An instrumentation amplifier and two independent chopper-stabilized delta-sigma modulators amplify and convert the transducer's output and excitation. Digital division of the two independent conversions produces a 20-b ratiometric measurement. Drift due to external thermocouple junctions and RF rectification is eliminated by AC excitation of the transducer. Interference (50/60 Hz) is eliminated by a digital FIR filter that has a -3 dB bandwidth of 15 Hz. Offset and gain errors are corrected by digital calibration. The input-referred noise of this converter is 150 nV_rms and the linearity is 110 dB. The converter gain and offset drifts are less than 2.5 p.p.m./°C and 15 nV/°C, respectively. This 2-μm CMOS chip consumes 30 mW of power and has an area of 25.5 mm²     

A DC-coupled wide dynamic range AGC amplifier IC for 560-Mbit/s optical transmission

A wide-band high-gain AGC amplifier stabilizing the output dc level against a broad gain variation is proposed and monolithically integrated using high-speed 1-μm Si-bipolar IC technology. The fabricated IC exhibits a maximum gain of 39 dB, gain dynamic range of 44 dB, bandwidth of 800 MHz, and output dc-level fluctuation of 8 mV, and realizes wide dynamic range and direct dc-coupling of the multistage AGC amplifier. Also, in order to examine the feasibility of the fabricated IC, a 1.5-μm-wavelength optical transmission experiment was carried out using DFB-LD and InGaAs-APD. Measured minimum received optical power for an error rate of 10^-9is -40 dBm at 560 Mbit/s and -38 dBm at 1.12 Gbit/s. Optical dynamic range of 30 dB is also achieved by using the fabricated IC and APD.     

InGaAs/InGaAsP MQW optical amplifier integrated withgrating-assisted vertical-coupler noise filter

A photonic integrated circuit with an InGaAs/InGaAsP multiple-quantum-well (MQW) traveling-wave optical amplifier and a grating-assisted vertical-coupler filter as a noise filter have been demonstrated. A fiber-to-amplifier/filter gain of ~0.5 dB and a 3-dB filter bandwidth (FWHM) of ~70 Å at 1.56 μm filter center wavelength have been achieved. This photonic circuit is potentially suitable as a building-block for preamplifier lightwave receivers or high-gain, high-power optical amplifiers which are essential for optical communication systems and lightwave networks     

Gain characteristics of an Er3+-doped multicomponentglass single-mode optical fiber

Experimental results on gain characteristics of an Er³⁺-doped multicomponent glass single-mode optical-fiber amplifier are reported. This amplifier shows a gain spectrum with twin gain peaks of 1.535 and 1.543 μm, providing a broadened gain bandwidth. The apparent 6-dB gain bandwidth is 12 nm. Furthermore, the signal gain of 17 dB and 15-mW pump power is realized at a signal wavelength of 1.536 μm, and a signal gain coefficient of 1.4 dB/mW is achieved     

Amplification at 10.6 µ in the negative glow of a hollow-cathode discharge in a CO2-He mixture

An amplifier for 10.6-μ radiation of a CO2laser has been constructed using the negative glow of a hollow-cathode discharge. The single-pass gain of 10 percent per meter reported here from such a discharge in a CO2-He mixture is less than that realizable in the positive column of a glow discharge used for CO2lasers under comparable conditions. The addition of N2, CO, or O2was not found to increase the gain.     

A high dynamic range ultralow-current-mode amplifier with pico-ampere sensitivity for biosensor applications

A novel ultralow-current-mode amplifier (ULCA) serving for on-chip biosensor signal pre-amplification in the integrated biosensing system (IBS) has been presented and verified in SMIC 0.18 μm CMOS technology by elaborately considering gain, bandwidth, noise, offset, and mismatch. The proposed ULCA solved the noise, bandwidth, and current headroom dilemma in the reported works, and can completely satisfy the specifications of IBS. It provides a current gain of 20 dB, 3 dB bandwidth of 7.03 kHz and input dynamic range of 20 bit, with only 1 nA of DC quiescent current, while the input offset current and noise current are less than 16.0 pA and 4.67 pArms, respectively.     

Broadband cryogenic parametric amplifier operating at 11.6 GHz

A machine-cooled cryogenic parametric amplifier that operates at 20 K is described. The 2-stage amplifier has a 0.5 dB bandwidth of 600 MHz at 20 dB gain and an effective input noise temperature in the range 47?51 K over the frequency band of 11.3 to 11.9 GHz     

An inductance enhancement technique and its application to a shunt-peaked 2.5 Gb/s transimpedance amplifier design

This brief presents a bandwidth enhancement technique that is applicable to gigahertz-range broadband circuits. Using the inductance enhancement technique proposed in this brief, a 2.5-Gb/s transimpedance amplifier (TIA) has been implemented based on a 0.35-/spl mu/m CMOS technology. With the input noise reduction, the TIA with the proposed active inductor loads improves the overall system performances including more that 90% increase in bandwidth. Measurements show the bandwidth of 1.73 GHz, transimpedance gain of 68 dB/spl Omega/, and the averaged input referred noise current of 3.3 pA//spl radic/Hz, respectively, while dissipating 50 mW of dc power.