Robust highly linear high-frequency CMOS OTA with IM3 below - 70 dB at 26 MHz

An enhanced configuration for a linearized MOS operational transconductance amplifier (OTA) is proposed. The proposed fully differential OTA circuit is based on resistive source degeneration and an improved adaptive biasing technique. It is robust to process variation, which has not been fully shown in previously reported linearization techniques. Detailed harmonic distortion analysis demonstrating the robustness of the proposed OTA is introduced. The transconductance gain is tunable from 160 to 340 /spl mu/S with a third-order intermodulation (IM3) below -70 dB at 26 MHz. As an application, a 26-MHz second-order low-pass filter fabricated in TSMC 0.35-/spl mu/m CMOS technology with a power supply of 3.3 V is presented. The measured IM3 with an input voltage of 1.4 Vpp is below - 65 dB for the entire filter pass-band, and the input referred noise density is 156nV//spl radic/Hz. The cutoff frequency of the filter is tunable in the range of 13-26 MHz. Theoretical and experimental results are in good agreement.     

An OTA gain enhancement technique for low power biomedical applications

The performance requirement of an operational trans-conductance amplifier (OTA) for the high gain and low power neural recording frontend has been addressed in this paper. A novel split differential pair technique is proposed to improve the gain of the OTA without any additional bias current requirements. The design demonstrates a significant performance enhancement when compared to existing techniques, such as gain-boosting and recycling. A qualitative and quantitative treatment is presented to explore the impact of the split ratio on the performance parameters of gain, bandwidth, and linearity. A prototype implemented in TSMC 65 nm CMOS technology achieved 68 dB open loop-gain (13 dB higher than the conventional circuit) and a 17 kHz 3-dB bandwidth. A linearity of ? 62 dB has been achieved with 7 mV pk–pk signal at the input. The circuit operates from a 1 V supply and draws 0.6 uA static current. The prototype occupies 3300 um² silicon area.     

Ge-laminated polarizer for 790-850-nm applications with extinctionratios larger than 50 dB and insertion losses below 0.4 dB

A laminated structure composed of alternating layers of Ge and SiO ₂ (Ge-LAMIPOL) is usable as a miniaturized polarizer at 790-850 nm in fiber optic gyroscopes, for instance. However, peeling of the sputter deposited layers, due to the weak binding strength between Ge and SiO₂, is a serious problem during the slicing process in preparation for assembly in the fiber. In order to improve the adhesive strength, the 1-nm-thick Si layers are inserted between Ge and SiO₂ layers. The Si layer functions as the adhesive layer via the Si-O bonding formation in place of the weaker Ge-O bond. The new Ge-LAMIPOL, including 125 layers of (1-nm Si)/(4.5-nm Ge)/(1-nm Si)/ (800-nm SiO₂) is successfully prepared without any fracture. The extinction ratio and the insertion loss were 51 and 0.33 dB at 850 nm, respectively, corresponding to 59.6 and 0.36 dB as the designed values     

A low-transconductance OTA with improved linearity suitable for low-frequency Gm-C filters

A fully differential operational transconductance amplifier is presented in this paper with enhanced linearity and low transconductance, suitable for low-frequency Gm-C filters. This paper also proposes a new common-mode feedback scheme that presents low sensitivity to large differential voltage swings at the OTA outputs. The proposed OTA was employed in the design of a fully-integrated Gm-C low-pass filter with a cutoff frequency of 30 kHz. The Gm-C filter was fabricated in a 0.35 μm CMOS technology and presented a THD at the output less than 1% for input signals with differential amplitudes up to 3.2 V.     

A low-power 65-nm CMOS mixer linearized with IM2 injection for V2X applications

Analog Integrated Circuits and Signal Processing - In this paper, high linearity, low power down-conversion mixer is presented with a 65-nm CMOS process for vehicle-to-everything (V2X)...     

Highest efficiency, linear X-band performance using InP DHBTs - 48%PAE at 30 dB C/IM3

InP single heterojunction bipolar transistors have previously demonstrated 5-10 dB lower third-order intermodulation products (IM3) compared to GaAs heterojunction bipolar transistors (HBTs) under low voltage (2 V) operation. This paper reports excellent single-tone and two-tone X-band operation, including high two-tone power-added efficiency (PAE), on linear InP double heterojunction bipolar transistors (DHBTs) operated at V_ce=4 V. The InP DHBT demonstrated a 30 dB carrier to third-order intermodulation product (C/IM3) output power ratio simultaneously with 48% two-tone PAE. This is the highest known efficiency of an X-band device under linear (30 dB C/IM3) operation. This is especially significant for microwave power amplifiers for satellite communication transmitters, where lower intermodulation distortion is normally accomplished by backing off in RF drive and output power, thus sacrificing PAE performance     

Design of high-Q 3-D integrated inductors for high frequency applications

Design of 3-Dimensional micromachined inductors on high-(10 KΩ·cm) and low-resistivity(10 Ω·cm) Si substrate fabricated using stress metal technology we have developed [1, 2] is presented. Using high frequency electromagnetic simulation of 3-Dimensional inductors performed by Ansoft HFSS®, we have investigated the effects of number of turns, effective radius, metal line width, and different substrates on the quality factor, Q and self-resonant frequency, f _sr of these inductors. We also have compared the simulated results with the measurement results of 3-D inductors fabricated using this technology.     

一个基于65 nm CMOS工艺具有17.3 dB增益的47-67 GHz宽带低噪声放大器

报道了一个基于65 nm CMOS工艺具有17.3 dB增益的47-67 GHz宽带低噪声放大器（LNA）。文中首先阐述了毫米波电路的特征,并讨论了其设计方法。LNA的宽带输入匹配通过源极电感退化获得,这种结构在低GHz频段为窄带匹配,但由于栅漏电容Cgd的存在,在毫米波频段其进化为宽带匹配。为了使噪声系数（NF）最小化,LNA在第一级使用了共源（CS）结构而不是cascode结构,同时文中也探讨了噪声匹配的原理。LNA的后两级使用cascode结构以提高功率增益。对共栅（CG）晶体管中栅极电感的增益提升效应进行了分析。级间T形匹配网络用来提升电路带宽。所有片上电感和传输线都在3维电磁仿真工具中建模和仿真以确保成功的设计。测试结果显示LNA在60 GHz处取得最高的 17.3 dB增益,同时3-dB带宽为20 GHz（47-67 GHz）,涵盖所需要的59-64 GHz频段,并在62 GHz取得最低的4.9 dB噪声系数。整个LNA从1.2 V电源处吸收19 mA电流,芯片包括焊盘占用面积为900×550 μm2。     

应用于DRM/DAB系统的高转换增益及线性度优化的新结构混频器

This paper focuses on a new design of a down-conversion mixer for a low-IF wideband receiver.Based on the folded structure and differential multiple gated transistor(DMGTR) technique,a novel quadrature mixer with a high conversion gain,a moderate linearity,and a moderate NF is proposed.The mixer is designed and implemented in a 0.18-m CMOS process,and can operate in a frequency range from 150 kHz to 1.5 GHz.The circuit performance is confirmed by both simulation and measurement results.The measurement results exhibit a peak conversion gain of 13.35 dB,a high third order input referred intercept point of 14.85 dBm,and a moderate single side band noise figure of 10.67 dB.Moreover,the whole quadrature mixer core occupies a compact die area of 0.122 mm2.It consumes a current of 3.96 mA(excluding the output buffers) under a single supply voltage of 1.8 V.     

A microwave Doherty amplifier employing envelope tracking technique for high efficiency and linearity

In this letter, we demonstrate a microwave Doherty amplifier employing an input signal envelope tracking technique. In the amplifier, the gate bias of the peaking amplifier is controlled according to the magnitude of the envelope. A 2.14-GHz Doherty amplifier is implemented using 4-W PEP LDMOSFETs, and an adaptive controlled gate bias circuit is constructed and the control shape is optimized experimentally. The performance of the microwave Doherty amplifier is compared with that of a class AB amplifier using one-tone, two-tone, and forward-link wideband code-division multiple access (WCDMA) signals. For a forward-link WCDMA signal, the measured power added efficiency (PAE) of the microwave Doherty amplifier is 39.4% at -30 dBc adjacent channel leakage ratio (ACLR), while that of the comparable class AB amplifier is 24.2% at the same ACLR level.     

激光制备高介CaTiO3-CaTiSiO5高频介质陶瓷

采用激光烧结技术成功制备致密、高介电常数的CaTiO3-CaTiSiO5高频介质陶瓷。使用X射线衍射仪、扫描电子显微镜分析样品的晶相组成和显微组织,利用精密阻抗分析仪测试陶瓷样品的介电性能。结果表明,激光烧结CaTiO3-CaTiSiO5介质陶瓷致密、介电常数（εr=376）高达固相烧结样品的5倍,这应归因于激光烧结C...     

A 6-7 GHz, 40 dB receiver RF front-end with 4.5 dB minimum noise figure in 0.13μm CMOS for IR-UWB applications

A wideband receiver RP front-end for IR-UWB applications is implemented in 0.13μm CMOS technology. Thanks to the direct sub-sampling architecture,there is no mixing process.Both LNA and VGA work at RF frequencies.To optimize noise as well as linearity,a differential common-source LNA with capacitive cross- coupling is used,which only consumes current of 1.8 mA from a 1.2 V power supply.Following LNA,a two-stage current-steering VGA is adopted for gain tuning.To extend the overall bandwidth,a three-stage staggered peaking technique is used.Measurement results show that the proposed receiver front-end achieves a gain tuning range from 5 to 40 dB within 6-7 GHz,a minimum noise figure of 4.5 dB and a largest IIP₃ of-11 dBm.The core receiver （without test buffer） consumes 14 mW from a 1.2 V power supply and occupies 0.58 mm² area.     

A CMOS line driver with 80-dB linearity for ISDN applications

A high-performance CMOS line driver for ISDN U-interface transceiver applications has been designed and fabricated. Careful study of requirements and trade-offs affecting linearity, power efficiency, and quiescent current presented in this work has resulted in a circuit structure featuring a highly linear input/output characteristic and well-controlled quiescent current. The prototype line driver is capable of delivering a 5-V_pp signal of up tp 80 kHz to a 60-Ω load while exhibiting linearity on the order of 77 ± 5 dB and operating from a single 5-V power supply. Linearity better than 70 dB is maintained for load resistances as low as 20 Ω     

A fully matched high linearity 2-W PHEMT MMIC power amplifier for 3.5 GHz applications

A 2-W monolithic microwave integrated circuit power amplifier, operating between 3.3 and 3.8GHz by implementing AlGaAs/InGaAs/GaAs pseudomorphic high electronic mobility transistor for the applications of wideband code division multiple access, wireless local loop, and multichannel multipoint distribution service, is demonstrated. This two-stage amplifier is designed to fully match 50/spl Omega/ input and output impedances. With a dual-bias configuration, the amplifier possesses the characteristics of 30.4dB small-signal gain and 34dBm 1-dB gain compression power with 37.1% power added efficiency. Moreover, with a single carrier output power level of 24dBm, high linearity with a 43.5-dBm third-order intercept point operating at 3.5GHz is also achieved.     

Constant voltage scaling of FETs for high frequency and high power applications

A constant voltage scaling scheme is examined for the enhancement of frequency and power performance of FETs. For low electric fields, this scheme is self-consistent within Shockley's formulation and improves the overall frequency and power performance figure of merit by a factor of κ⁶ with a κ times reduction in the device area. For high electric fields, the improvement is reduced to κ³ times due to the velocity saturation effect. Reduced breakdown voltage further limit the improvement.     

Tuning of long-period fibre gratings written by CO/sub 2/ laser with resonant transmission below -45 dB

Long-period fibre gratings (LPGs) that were made to have resonant transmission below -45 dB are tuned via their simultaneous bending and straining. It was found that the position of the LPG resonance can be tuned over more than 6 nm, maintaining the level of the resonant transmission below -45 dB. Fine tuning of the resonance transmission without a change in its spectral position is also demonstrated. The reported LPGs should satisfy the strictest requirements on the control of LPG filtering characteristics, especially in terms of the phase response     

Characterization of liquid crystal polymer for high frequency system-in-a-package applications

Liquid crystal polymer (LCP) is a promising substrate for electronics packaging. In this paper, the high frequency characteristics of LCP were investigated using a microstrip ring resonator to verify the possibility of applying the material in RF packaging. The relative dielectric constant and the loss tangent have been measured. The radiation loss of the ring is considered to accurately determine the loss tangent. A GaAs MMIC switch circuit was fabricated using LCP as substrate to demonstrate the application of this material for system-in-a-package. From the high frequency measurements, it is shown that LCP has low dielectric constant and low loss tangent in the frequency range from 1 GHz to 35 GHz. It is also found that LCP can be used in system-in-a-package applications.     

Ultra-wideband optical amplification with 3 dB bandwidth of 65 nmusing a gain-equalised two-stage erbium-doped fibre amplifier and Ramanamplification

A 3 dB gain-reduction bandwidth up to 65 nm (1549-1614 nm) is achieved using a two-stage erbium-doped fibre amplifier, together with an intermediate equaliser and Raman amplification in the transmission fibre     

A high sensitive 66 dB linear dynamic range receiver for 3-D laser radar

This study presents a CMOS receiver chip realized in 0.18 μm standard CMOS technology and intended for high precision 3-D laser radar. The chip includes an adjustable gain transimpedance pre-amplifier, a post-amplifier and two timing comparators. An additional feedback is employed in the regulated cascode transimpedance amplifier to decrease the input impedance, and a variable gain transimpedance amplifier controlled by digital switches and analog multiplexer is utilized to realize four gain modes, extending the input dynamic range. The measurement shows that the highest transimpedance of the channel is 50 kΩ, the uncompensated walk error is 1.44 ns in a wide linear dynamic range of 66 dB (1:2000), and the input referred noise current is 2.3 pA/√Hz (rms), resulting in a very low detectable input current of 1 μ A with SNR=5.     

A novel SOI-MESFET with parallel oxide-metal layers for high voltage and radio frequency applications

In this paper a novel silicon on insulator metal-semiconductor field effect transistor is proposed for high voltage and radio frequency applications. This structure includes additional parallel oxide-metal layers in channel region which we called POML-SOI-MESFET. Our 2-D simulations demonstrate that the presence of parallel layers increases the breakdown voltage. Higher critical electric field of additional oxide region than Si and the effect of inserted metal layer in dispersing the potential lines at the gate edge and also at drift region, boost the breakdown voltage of the device from 13.5 V in conventional structure (C-SOI-MESFET) to 29 V in POML structure which shows 114% improvement. Maximum output power density experiences 133% enhancement by applying POML structure. Also, parallel layers improve the maximum oscillation and cut-off frequencies by 11% and 3.3%, respectively with modifying the gate-drain capacitance. Thermal analysis shows that beside these improvements, the POML maintains the thermal conductivity of the device. In order to attain the best results, POML dimensions are optimized carefully. Simultaneous improvement in breakdown voltage, cut-off frequency, maximum oscillation frequency, and maximum output power density makes our proposed structure an efficient device for applications with higher voltages and frequencies.