A 0.1–5 GHz Cryogenic SiGe MMIC LNA

In this letter, the design and measurement of the first SiGe integrated-circuit LNA specifically designed for operation at cryogenic temperatures is presented. At room temperature, the circuit provides greater than 25.8 dB of gain with an average noise temperature $(T_{e})$ of 76 K $(NF=1 {rm dB})$ and $S_{11}$ of $-$ 9 dB for frequencies in the 0.1–5 GHz band. At 15 K, the amplifier has greater than 29.6 dB of gain with an average $T_{e}$ of 4.3 K and $S_{11}$ of $-$14.6 dB for frequencies in the 0.1–5 GHz range. To the authors' knowledge, this is the lowest noise ever reported for a silicon integrated circuit operating in the low microwave range and the first matched wideband cryogenic integrated circuit LNA that covers frequencies as low as 0.1 GHz.      

FM microwave multiplexed broad-band distribution systems using Er3+ fiber amplifiers and preamplifiers

The use of an Er³⁺ fiber preamplifier for microwave multiplexed systems and the use of an inline Er³⁺ amplifier in microwave multiplexed systems for signal distribution are reported. The improvement in receiver sensitivity as a preamplifier, without optical filtering, was 9 dB. No power penalty due to amplified spontaneous emission was found when the amplifier was used in a 30-channel signal distribution system     

An 8-Bit Flash Analog-to-Digital Converter in Standard CMOS Technology Functional From 4.2 K to 300 K

This paper presents the first Flash analog-to-digital converter (ADC) in standard CMOS technology that functions from 300 $~$K (room temperature) down to 4.2$~$K. It has been designed to operate in cryogenic sensor systems as they are cooled from room temperature to their final cryogenic operating temperature. In order to preserve the circuit's performance over this wide temperature range, even in the presence of temperature-induced transistor anomalies, dedicated architecture and switching schemes are employed. SPICE models for adequate circuit simulation at 4.2 K have been extracted. A first prototype of the chosen architecture, an 8-bit ADC in a standard 0.7$ muhbox{m}$ CMOS technology, achieves a differential nonlinearity (DNL) of 0.5 LSB at room temperature and 1 LSB at 4.2 K at a sampling frequency of 12.5 kHz.      

Experimental Demonstration of Optical DQPSK Receiver Based on Frequency Discriminator Demodulator

This paper presents experimental data demonstrating a novel differential quadrature phase-shift keying receiver based on optical frequency discriminator demodulator with direct detection. The experimental results confirm theory, showing a factor of 2$times$ enhanced tolerance to chromatic dispersion compared with a conventional delay-interferometer-based demodulator with balanced detection. The frequency discriminator direct detection receiver also shows a significant improvement in tolerance to Gordon–Mollenauer nonlinear phase noise.      

A Short Range, Low Data Rate, 7.2 GHz-7.7 GHz FM-UWB Receiver Front-End

A 9 mW FM-UWB receiver front-end for low data rate ( $≪$$ hbox{50~kbps}$), short range ( $≪$$hbox{10~m}$) applications operating in the ultra-wideband (UWB) band centered at 7.45 GHz is described in this paper. A single-ended-to-differential preamplifier with 30 dB voltage gain, a 1 GHz bandwidth FM demodulator, and a combined (preamp/demodulator) receiver front-end were fabricated in 0.25 $muhbox{m}$ SiGe:C BiCMOS and characterized. Measured receiver sensitivity is $-hbox{85.8~dBm}$ while consuming 9 mW from a 1.8 V supply, and $-hbox{83~dBm}$ consuming 6 mW at 1.5 V. 15-20 m range line-of-sight in an indoor environment is realized, justifying FM-UWB as a robust radio technology for short range, low data rate applications. Multi-user and interference capabilities are also evaluated.      

2.488 Gb/s-318 km repeaterless transmission using erbium-dopedfiber amplifiers in a direct-detection system

The authors have achieved a 2.488 Gb/s, 318 km repeaterless transmission without any fiber dispersion penalty through a nondispersion-shifted fiber in a direct detection system. The system was loss limited with a T-R power budget of 57 dB. Three key components enabled the authors to achieve this result: (1) a Ti:LiNbO₃ external amplitude modulator enabling a dispersion-free transmission, (2) erbium-doped fiber amplifiers increasing the transmitting power to +16 dBm, and (3) an erbium-doped fiber preamplifier enabling a high-receiver sensitivity of -4.1 dBm for 10^-9 BER. To the author's knowledge, this result is the longest repeaterless transmission span length ever reported for direct detection at this bit rate. From the experimental results and a theoretical model, the authors identified the sources of the receiver sensitivity degradation from the quantum limit (-48.6 dBm) and estimated the practically achievable receiver sensitivity of ~-44 dBm (~-124 photons/bit) for 2.5 Gb/s optical preamplifier detection     

A precision noise measurement and analysis method used to estimate reliability of semiconductor devices

In this paper, some problems with previous ultra-low noise measurement methods have been discussed, then a double-channel preamplifier cross-spectrum measurement method has been adopted, different from the previous cross-correlation method [A. van der Ziel, Noise: Sources, Characterization, Measurement, p. 54. Prentice-Hall, Englewood Cliffs, NJ (1970), L. Stor, Experimental techniques in noise measurement with special emphasis on precision measurement, Proc. 10th Int. Conf. on Noise in Physical Systems, pp. 551–560. Budapest, Hungary (1989)] in that an average periodogram using a windowing procedure has been performed. The theoretical analysis shows that the expected value of the cross-spectrum is incoherent with background noise and zero-drift from the preamplifier and power supply system, the average periodogram can decrease the variance of the periodogram and the additional bias of the cross-spectrum periodogram.Experimental results demonstrate that if the equivalent input noise of measuremental set-up is two orders of magnitude lower than the noise of each preamplifier, then an ultra-low noise spectrum can be measured accurately, the low limit is about 0.1 nV/√Hz at 1 kHz, which is 20 dB lower than the noise of each preamplifier. The thermal noise of a small resistance and the shot noise of a diode under forward conditions have been measured, the experimental results are in good agreement with the theoretical value, this means that this method is feasible and accurate for an ultra-low noise spectrum measurement.Finally, the noise spectrum analysis procedure based on the curve fitting method has been presented, which ensures that we obtain an accuracy value of three noise components in the semiconductor, i.e. noise, white noise and g-r noise. This noise spectrum analysis method is a useful tool for investigation of noise mechanism, the diagnosis of defects in semiconductors and reliability estimation.     

A 40-Gb/s preamplifier using AlGaAs/InGaAs HBTs with regrown basecontacts

A preamplifier for 40-Gb/s optical transmission systems incorporating AlGaAs/InGaAs heterojunction bipolar transistors (HBTs) with p⁺ regrown extrinsic base layers is described. The HBTs have a heavily doped regrown p⁺-GaAs layer in the extrinsic base regions and a thin graded InGaAs strained layer for the intrinsic base. Their measured peak f_max is above 200 GHz. The developed preamplifier provides a bandwidth of 38.4 GHz and a transimpedance gain of 41.1 dB Ω. Moreover, the frequency response as an optical receiver has a bandwidth of 32 GHz. These characteristics make the preamplifier suitable for use in a 40-Gb/s optical receiver. These results show that AlGaAs/InGaAs HBTs with p⁺ regrown extrinsic base layers are very promising for use in 40-Gb/s optical transmission systems     

The Kink Effect at Cryogenic Temperatures in Deep Submicron AlGaN/GaN HEMTs

The kink effect has been studied in deep submicron AlGaN/GaN high-electron mobility transistors by measuring their DC, RF and pulsed performance at cryogenic temperatures. In these devices, the kink effect is mainly due to traps: it appears at $T ≪ hbox{260} hbox{K}$ and can be removed either by applying UV light or biasing the gate with short pulses. Its appearance is related to the fluorine-based treatment ($hbox{CF}_{4}/hbox{O}_{2}$ plasma) used for etching the passivant, treatment which creates traps below and around the gate. This link between the kink and the etching treatment has also been confirmed in optically defined gate devices with different fluorine plasma exposure times.      

Unequal Error Protection: An Information-Theoretic Perspective

An information-theoretic framework for unequal error protection is developed in terms of the exponential error bounds. The fundamental difference between the bit-wise and message-wise unequal error protection ( UEP) is demonstrated, for fixed-length block codes on discrete memoryless channels (DMCs) without feedback. Effect of feedback is investigated via variable-length block codes. It is shown that, feedback results in a significant improvement in both bit-wise and message-wise UEPs (except the single message case for missed detection). The distinction between false-alarm and missed-detection formalizations for message-wise UEP is also considered. All results presented are at rates close to capacity.      

A Novel 3–5 GHz Active Matched Filter for Impulse Radio Ultra-Wideband

In this letter, a novel active matched filter for UWB-IR lower band (3.1–4.85 GHz) is presented. The signal to noise ratio is improved at the output using a tapped delay line with a common source amplifier. An artificial transmission line is used for wideband impedance matching. The matched filter achieves a power gain of 9.8 dB at center frequency. Input matching is better than ${-}19$ dB and output matching is better than ${-}15$ dB. The averaged SNR improvement is 4.6 dB using peak detection. Input referred 1-dB compression point is 0.7 dBm at the center frequency. The matched filter is biased from a 1.5 V supply with a total power consumption of 38 mW.      

Optical preamplifier receiver for spectrum-sliced WDM

Spectrum-slicing provides a low-cost alternative to the use of multiple coherent lasers for wavelength division multiplexing (WDM) applications by utilizing spectral slices of a single broadband noise source for creating the multichannel system. In this paper we analyze the performance of both p-i-n and optical preamplifier receivers for spectrum-sliced WDM using actual noise distributions, and the results are compared with those using the Gaussian approximation. This extends prior results of Marcuse for the detection of deterministic signals in the presence of optical amplifier and receiver noise. Although the methodology is similar, the results are considerably different when the signal is itself noise-like. For the case of noise-like signals, it is shown that when an optical preamplifier receiver is used, there exists an optimum filter bandwidth which minimizes the detection sensitivity for a given error probability. Moreover the evaluated detection sensitivity, in photons/bit, represents an order of magnitude (>10 dB) improvement over conventional detection techniques that employ p-i-n receivers. The Gaussian approximation is shown to be overly conservative when dealing with small ratios of the receiver optical to electrical bandwidth, for both p-i-n and preamplifier receivers     

Velocity and Mobility Investigation in 1-nm-EOT HfSiON on Si (110) and (100)—Does the Dielectric Quality Matter?

One of the fundamental questions for gate-stack scaling is whether the low-field mobility measured in long-channel devices is a good proxy for short-channel performance at high field. In this paper, we thoroughly investigate low- and high-field transports (velocity and mobility) in 1-nm-EOT high- $kappa$ materials on Si (100) and (110) down to cryogenic temperature. It is shown that scattering in Si substrate dominates the transport at high field, thus enabling relaxation of the low-field-mobility requirement for future scaling below 1-nm EOT.      

Reduction of Crosstalk Between Dual Power Amplifiers Using Laser Treatment

A cost-effective isolation technique using laser treatment is proposed to suppress the undesired crosstalk between dual power amplifiers (PAs), which are essential to multiple-input multiple-output communications system. Laser treatment not only reduces the small-signal coupling between dual PAs but also enhances the linearity of the PA under dual-PA operation mode. The figure of merit for the small-signal coupling has an improvement of 4.55 dB at 2.45 GHz, and the output power at 3% (${-}$ 30 dB) error vector magnitude (EVM) has a linearity improvement of 6.1 dB under 0-dB interference.      

Modulation and detection characteristics of optical continuous phase FSK transmission system

The modulation and differential detection characteristics of optical CPFSK transmission systems are investigated both theoretically and experimentally. The error rate expressions of differentially detected CPFSK are derived by considering phase noise of LD's. It is clear that the linewidth requirement is less than0.68 mpercent of the bit rate, wheremis modulation index. The performances of CPFSK are then experimentally presented at 400 Mbit/s using external optical feedback DFB LD's as the optical source. A beat spectral linewidth of less than 200 kHz for the transmitter and local oscillator LD's is achieved. The frequency response nonuniformity of frequency modulation efficiency is compensated by electrical circuits within 3 dB and 60°. To reduce IF thermal noise, a resonance-type preamplifier is used, with a 4.8 pA/sqrt{Hz}average input noise current density, and a receiver sensitivity 1.3 dB better than the conventional preamplifier. Differential detection of the 400-Mbit/s CPFSK modulation is performed. The generation of CPFSK is confirmed by good correlation between the output spectrum and theory. The average received optical power at a 10^-9bit error rate is -49.9 dBm which improves direct detection by 10.3 dB. No additional power penalties due to 290-km transmission exist.     

Rayleigh scattering influence on performance of 10 Gb/s opticalreceiver with Er-doped optical fiber preamplifier

The achievement of -30.8 dBm (630 photon/bit) receiver sensitivity at 10 Gb/s, with an Er³⁺-doped optical fiber preamplifier, is discussed. This is an 8.3-dB sensitivity improvement over the avalanche-photodiode/FET receiver. Power penalties caused by a noise increase due to Rayleigh backscattering by the transmission optical fiber have been evaluated. Approximately -30-dB Rayleigh scattering from a 20-km optical fiber resulted in a 3.5-dB power penalty for a 25-dB-gain optical amplifier     

A CMOS Hearing Aid Device

In this paper a CMOS Hearing Aid Device is described. The system is composed of a low-distortion low-noise preamplifier, an automatic gain control (AGC), a fully programmable switched-capacitor filter (equalizer), and a control system. The device has been fabricated in a 1.2 m CMOS analog process. The dynamic range of the device is 55 dB while the harmonic distortion components are below –50 dB. Experimental results show the feasibility of the proposed architecture.     

用于APD激光探测的电荷灵敏前置放大器设计

雪崩光电二极管（APD）作为探测元件实现光电转换广泛应用于激光脉冲探测技术中。前置放大器是影响APD激光脉冲探测系统好坏的关键因素,前置放大器的信噪比决定了整个探测系统的信噪比优劣。提出了电荷灵敏前置放大器应用于APD激光脉冲探测系统以提高探测距离和探测精度的方法。讨论了激光脉冲探测技术和APD特性,在此基础上设计了以结型场效应管和集成运放为主要器件的低噪声电荷灵敏前置放大器电路并对设计电路进行了实验分析。实验结果表明：将电荷灵敏前置放大器应用于APD激光脉冲探测系统可以有效提高系统的信噪比,改善激光探测性能。     

A JFET-CMOS radiation-tolerant charge-sensitive preamplifier

A monolithic charge-sensitive preamplifier based on n-channel junction field-effect transistors (JFETs) and p-channel MOS has been realized for applications with microelectrode detectors in elementary particle physics. Radiation resistance tests carried out with the preamplifier exposed to γ-rays emitted by a ⁶⁰Co source have shown no significant increase of the equivalent noise source up to 150-krd absorbed dose     

Automatic $P$-Phase Picking Based on Local-Maxima Distribution

In this paper, we propose a method for the automatic identification of $P$ -phase arrival based on the distribution of local maxima (LM) in earthquake seismograms. The method efficiently combines energy and frequency characteristics of the LM distribution (LMD). The $P$ detection is mainly based on the energy of a seismic event in the case the earthquake has higher amplitude than seismic background noise. Otherwise, it is based on the frequency of LM. Thus, the method provides robust detection of $P$-phase arrival in any quality type of seismic data. Moreover, it uses two sequential sliding signal windows yielding very high accuracy on the $P$-phase estimation. A hierarchical $P$-phase detection algorithm dramatically reduces the computational cost, making possible a real-time implementation. Experimental results from a large database of more than 80 low, medium, and high signal-to-noise ratio seismic events and comparison with existing methods in the literature indicate the reliable performance of the proposed scheme.