70 dB Dynamic Range CMOS Wideband Digital Variable Gain Amplifier for AGC in DVB-T/H Receivers

This paper presents a novel variable gain amplifier (VGA) design which is applied in the automatic gain control loop of digital video broadcasting (DVB) receivers designed for standards DVB-T/H. The VGA is composed of three cascaded tunable gain stages to provide a 70 dB dynamic range with 2 dB gain steps. Each gain stage is based on a digital variable gain amplifier (DVGA) which is composed of a plurality of gain blocks (GBs) and a fully differential degeneration amplifier (FDDA). The GBs of the DVGA are digitally controlled current mirrors. A common-mode feedback circuitry is used to stabilize the FDDA by providing a stable common-mode voltage. Physical measurements on silicon show that the gain error is merely 0.55 dB given a 70 dB tuning range. This work was supported by National Science Council, Taiwan, under contract nos. NSC96-2628-E-110-019 and NSC96-2920-E-110-001.     

几种全光逻辑门浅析

全光逻辑门是实现高速光分组交换、全光地址识别、数据编码、奇偶校验、信号再生、光计算和未来高速大容量全光信号处理的关键器件,本文介绍了几种基于半导体光放大器非线性效应的全光逻辑门,分析了它们的系统结构和工作原理,并对各自的特点进行了比较,展望了光逻辑门在未来的发展方向.     

Ka波段低噪声放大器的研制

毫米波低噪声放大器是毫米波接收系统的关键部件,本文设计的毫米波低噪声放大器采用BJ320波导口输入输出和微带探针过渡结构实现波导结构到微带平面电路的过渡,使用MMIC芯片微组装工艺实现电路的制作,在工作频带内,测得该低噪声放大器的增益大于16 dB,噪声系数小于2.7 dB,达到了工程使用的要求。     

实用运算放大器网络中的虚地性质

本文提出用一个理想电压控制电流源(VCCS)并接于嵌在一个倒相放大器电路中的实际运算放大器(OP.amp)输入端,虚地性质(VGP)可以扩展到使用的运算放大器单位增益带宽那样高的频率.文中给出用真正运算放大器的VCCS的实用电路.用互补变换法可得出非倒相放大电路图.     

注入锁定型半导体激光放大器的响应特性研究

本文讨论了注入锁定(IL)型半导体激光放大器的功率响应、频率响应特性,分析了锁定相位、注入光功率等对这些特性的影响。     

DESIGN AND ANALYSIS OF INTEGRATED OPERATIONAL AMPLIFIER XD1531 WITH LOW NOISE AT LOW FREQUENCIES

Principles of design are described for the low frequency integrated operationalamplifler XD1531 with low noise. The procedures of design of both the circuit structure and the tran-sistor shape are considered. The first stage of the circuit is designed with the methods of low noise atlow frequencies. The measures which decrease noises, especially, the 1/f noise originating .from thesemiconductor surface state and defects, are used for the transistor structure design. With analysisand comparison to products here and abroad in characteristics, it is shown that XD1531 has a lowernoise index at low frequencies than others, and the effectiveness of design methods for bringing lownoises have been demonstrated.     

A simple technique for automated performance testing of piezoelectric micro-motors by transient motion analysis

An automated method of testing a 5 mm diameter flextensional ultrasonic motor has been assembled using off-the-shelf components, which derives performance measurements from the transient start up and stopping behaviour of the motor using a non-contact position encoder. The method gives full performance characteristics in less than a second and it is scaleable for use with other sizes and other types of motor. Furthermore, it provides a relatively simple technique for non-contact measurements of position, angle or velocity that can be rapidly cycled as part of a development programme.

The method has shown sufficient sensitivity, using basic components, to measure torque in the range 10–200 μN m and speed in the range from 0 to over 2000 rpm. The torque and speed ranges are only dependant on the sensitivity of encoder instrumentation, inertial load on the motor and data acquisition. This system is believed to be a significant improvement over previously reported work that has detailed friction brake or manual ‘one-off’ systems and the test format has greater applicability for micro-motors that are used for their positioning capabilities.     

Compact VDTA-based current-mode electronically tunable universal filters using grounded capacitors

This paper presents a compact current-mode three-input single-output (TISO) type universal filter. Only one voltage differencing transconductance amplifier (VDTA) and two grounded capacitors are employed in the proposed filter. The circuit can realize lowpass, bandpass, highpass, bandstop and allpass biquadratic filter outputs by connecting the appropriate inputs, and offers electronic control of the natural angular frequency (ω₀) and quality factor (Q) by means of adjusting the transconductance gain of the VDTA. In addition, by slight modification of the proposed scheme, another more useful TISO construction with orthogonal ω₀–Q tuning has been obtained. Both the discussed universal filters have been shown to have low incremental active and passive sensitivities. To demonstrate the performances of the filters and verify the theoretical analysis, computer simulations are accomplished with the PSPICE program.     

Highly linear wide‐swing continuous tuning of CMOS transconductors

A technique to improve the input and output range of CMOS transconductors with resistive current division for continuous tuning is presented. Using it, a tunable transconductor is proposed which features high linearity over a wide input range and simplicity. Measurement results of the transconductor, fabricated in a 0.5 µm CMOS process, show an IM3 of ?66 dB for a ±1.65 V supply and two input tones centered at 1 MHz of 1 V_pp each, and only 0.7 mW of power consumption. This represents an improvement of 13 dB versus the same transconductor using conventional current division. Copyright © 2013 John Wiley & Sons, Ltd.     

程控技术在仪表中的应用

本文介绍了可编程放大器（ＰＧＡ）在仪表中的几种用途。较祥细地讨论了ＰＧＡ的３种基本组成方法及特点。同时，也指出了提高增益精度的一些措施