一种高阶通用对数滤波器的设计方法

提出一种高阶通用对数滤波器的设计方法.通过分析与利用n阶通用电流模式滤波器的传递函数,建立一种新的系统状态空间表达,使用模块化的结构设计方法,先设计单元模块电路,然后再按一定规则组合成整体电路.设计的整体电路能实现低通、高通、带通和带阻等多种滤波功能,且电路结构简单、易于集成、无源灵敏度很低.Pspice仿真表明,设计方法是可行的.     

具有宽调谐范围的低电压对数域二阶低通滤波器

提出了一个由BiCMOS构成的对数域二阶低通滤波器,并采用跨导线性原理分析得到其传递函数。分析了晶体管的寄生电容对此滤波器频率特性的影响。PSpice仿真结果表明,该对数域低通二阶节的实际频率特性和理想特性基本一致。且具有宽频率调谐范围、低工作电压和低失真等特点,可用于对数域高阶滤波器的设计。     

一种基于平衡式对数域积分器的高阶滤波器

提出了一个新的工作在甲乙类状态的平衡式对数域积分器 ,用跨导线性原理分析得到其传递函数。基于该积分器电路 ,采用无源网络模拟法设计出一个 1 d B波纹的五阶切比雪夫对数域低通滤波器。PSpice仿真结果表明 ,这种新型对数域滤波器能在低电压条件下工作 ,并具有高频、宽调谐范围和低失真等特点。     

新颖的对数域电流模式二阶低通带通滤波器设计

文中利用指数跨导元件，运用状态空间综合方法，设计了新颖的对数域电流模式二阶低通，带通滤波器。所提出的滤波器电路结构简单，具有很好的高频性能，适合于低电压工作，其截止频率由参考偏置电流控制，调节范围很宽。电路由双极型晶体管和接地电容构成，适合于全集成实现。ＰＳＰＩＣＥ仿真表明，所提出的电路是可行的。     

低功耗跨导-电容滤波器及其调谐电路的设计

设计了一种以Nauta跨导为单元结构的5阶切比雪夫跨导-电容带通滤波器及其调谐电路.该电路应用于低中频结构的北斗卫星导航接收机射频前端.滤波器的中心频率为4.092MHz,带宽设计为±2.046 MHz.该滤波器采用锁相环结构的片上自动频率调谐电路,用TSMC0.13 μm RF CMOS工艺实现,芯片面积仅为0.24 mm2,可以在低电压下工作,电路总功耗仅为1.68 mW.     

基于E型频变负阻的五阶椭圆高通滤波器设计

用电流传送器实现的E型频变负阻、接地电感和浮地电感作为单元电路,提出了实现高阶椭圆高通滤波器的设计方法.用该方法设计的有源滤波电路具有无源梯形网络原型的低灵敏度特性,给出了五阶椭圆高通滤波器的设计例子和PSPICE仿真结果.     

基于对数域无损积分器的高阶滤波器设计

提出利用双极型晶体管构成的对数域无损积分器以及对数压缩和指数扩展电路实现高阶滤波器.基于无源网络模拟,该设计不仅方法简单,而且使用元件种类很少,易于集成给出一个6阶Butterworth带通滤波器设计实例.PSpice仿真结果表明,该对数域滤波器能在低电压条件下工作,并具有高频、宽调谐范围和低失真等特性.     

用对数域电流模式电路实现连续小波变换

本文提出了用对数域电路实现连续小波变换的一种方法.利用复解调技术将设计带通滤波器组转化为设计相对简单的低通滤波器组问题,给出了分解与重构的系统流程.设计并分析了对数域电流控制振荡电路,对数域积分器和高斯滤波器等主要的模拟电路.     

低压低功耗阶跃增益对数域电流模滤波器的状态空间设计方法

本文提出了一种基于状态空间方程理论的阶跃增益对数域CMOS电流模滤波器设计新方法,并构建了构成阶跃增益对数域高阶滤波器的基本状态方程及其对应的基本电路单元.可简化电路设计,易于实现电路优化;MOS管工作在亚域值区,低电压低功耗;电路中间变量可观测,可实现阶跃增益及可调带宽.采用该方法,实现了一款基于0.35μm工艺的二阶CMOS对数域电路,工作电压1.4V,功耗15μW,电路面积150×160μm2.     

跨导线性MDDCCⅡ电路

提出了一个跨导线性MDDCCII电路,该电路全部由双极型晶体管构成。详细分析了其工作原理,并对该电路进行了硬件实验。该电路在0～1.5MHz以很小的跟踪误差满足MDDCCII理想端口特性,其中电压跟踪误差为0.01,同相电流跟踪误差为0.01,反相电流跟踪误差为0.02。作为应用,根据该MDDCCII电路构成了多功能二阶低通和高通滤波器电路,并对滤波器进行了硬件实验。     

A novel first-order log-domain allpass filter

This paper proposes a first-order allpass log-domain filter, which is systematically derived using the state-space synthesis procedure. To the best knowledge of the authors, the filter is the first log-domain first-order allpass filter in the literature. The proposed filter has a simple structure and can be electronically tuned. PSPICE simulations are given to confirm the theoretical analysis.     

Novel first-order differential class-AB log-domain allpass filters

The first-order differential class-AB log-domain filters are proposed. They are systematically derived using the state–space synthesis procedure. It is also demonstrated that the present second filter cannot be realized without using differential class-AB type. To the best knowledge of the authors, the filters are the first log-domain first-order allpass filters in the literature. PSPICE simulations are performed using both, bipolar junction transistors (BJT) and ideal devices to confirm the theoretical analysis. Tolerable differences are observed due to BJT non-idealities such as finite-beta, non-zero ohmic junction resistances and early voltages.     

A new 5th-order differential type class-AB log-domain elliptic lowpass filter for video frequency applications

This paper proposes a new current-mode 5th-order differential type class-AB log-domain elliptic lowpass filter for video frequency applications. The design is based on the state-space synthesis method. The proposed filter has 5.75 MHz cut-off frequency with maximum 0.177 dB passband ripple and attenuation greater than 40 dB at 7.88 MHz. Only BJTs and grounded capacitors were used, and operated with single power supply of 2.5 V. Since the parameters of proposed filter are tunable, it is easy to control of cut-off frequency. This adjustment is accomplished by changing external currents. SPICE simulations are given to confirm the theoretical analysis. For this purpose, the filter is simulated by using both idealized BJT models and AT&T CBIC-U2 type transistors.     

Log-domain synthesis of nth order universal filter

In this paper a synthesis approach for an nth-order universal log-domain filter comprising lowpass (LP), highpass (HP) and bandpass(BP) filtering functions is proposed. The approach is simple and the method of extending the approach to two uncommon filtering functions, lowpass notch (LPN) and high pass notch (HPN), is also given. The second, fourth and sixth-order universal log-domain filters are designed using log-exponential relationship between voltage and current of bipolar junction transistors (BJT) for the verification of approach. The performance of proposed universal filter and that of extended LPN and HPN was verified through simulation results.     

Log-domain wave filters

A systematic method for designing log-domain wave filters is presented. Wave filters simulate topologically and functionally passive doubly terminated LC ladder prototype filters of low sensitivity. The design in the log-domain is based on a transposition of the signal flow graph (SFG) that corresponds to the wave equivalent of elementary two-port blocks in the linear domain, to the corresponding log-domain SFG. This is achieved by using an appropriate set of complementary operators, in order to preserve the linear operation of the whole circuit. Simulation results of a fifth-order low-pass and a fourth-order bandpass log-domain wave filter are given, using HSPICE. The proposed circuits are suitable for low-voltage operation and in high-frequency applications.     

Analysis and Compensation of Log-Domain Biquadratic Filter Response Deviations due to Transistor Nonidealities

A translinear log-domain integrator, the powerhouse of log-domain filtering techniques, is analyzed to determine its deviations due to major time-invariant bipolar transistor imperfections, such as parasitic emitter and base resistances, finite beta, Early effect, and area mismatches. The results are used to predict the transfer function deviations of biquad filters, for both lowpass and bandpass filter responses. It will be shown that the errors can be understood and categorized into integrator scalar and negative feedback errors, and how they can be electronically compensated. SPICE simulations, both large and small-signal analysis, are performed to verify the results.     

A micropower class-AB CMOS log-domain filter for DECT applications

This paper presents a micropower second-order low-pass filter using the log-domain principle and integrated in a 0.35-μm CMOS process. It has been designed as an antialiasing filter for a DECT transceiver with a 45-kHz nominal cutoff frequency. The circuit uses transistors biased in weak inversion without requiring separate wells. It operates at 1.5-V supply voltage and its current consumption is 8 μA in idle mode. The log-domain filter is implemented with an on-chip conditioner which allows class-AB operation. It can process input currents at 5 kHz that are 25 times larger than the 200-nA bias current. Measurements up to 500 times the bias current have been done, since at 1 kHz the input current is only limited by the supply voltage     

Log-domain high-order low-pass and band-pass filters

Continuous time current-mode high-order low-pass and band-pass filters based on the log-domain concept are presented in this paper. The passive RLC ladder networks are used as the prototype to achieve the proposed filter by simulating the RLC network synthesis method. The achieved filters have inherited the good sensitivity performance from the RLC passive prototype. Fifth-order RLC ladder low-pass filter and sixth-order RLC ladder band-pass filter are used as prototypes and the signal flow graph (SFG) technique is used for the synthesis. The SFG can identify group of integrators and several signal paths. Log-domain lossy and lossless integrators based on BJT technology are deployed to achieve the integrators for realization of proposed filters. The simulations were carried out and the results exhibited several features which are in agreement with the RLC prototype. The frequency response of filters along 100 kHz to 10 MHz can be electronically tuned through 5–500 µA of bias currents. The THD lower than 1% of LP and BP filters were measured at 10 MHz input. The multi-tone tested was included in the paper for verifying the performance of proposed LP and BP filters. The intermodulation distortions around −50 dB and −60 dB were also investigated for the proposed LP and BP filters.     

A Bernoulli Cell-Based Investigation of the Non-Linear Dynamics in Log-Domain Structures

This paper presents a low-level treatment of the non-linear dynamics encountered in log-domain structures, by means of a non-linear circuit element termed a Bernoulli Cell. This cell comprises an npn BJT and an emitter-connected grounded capacitor, and its dynamic behavior is determined by a differential equation of the Bernoulli form. The identification of the Bernoulli Cell leads to the creation of a system of linear differential equations which describe the dynamics of the derived log-domain state-variables. Furthermore, it is shown that the Bernoulli Cell has a memristive type dynamic behavior. The approach aids the analysis of log-domain circuits, and allows the internal non-linear currents to be conveniently expressed in closed analytical form. A worked example for a specific topology with confirming simulation results in both frequency and time-domain is presented. The celebrated Hodgkin-Huxley nerve axon membrane dynamics are also successfully simulated as a characteristic example of memristive behavior.     

Nonlinear dynamics of first- and second-order log-domain circuits

Log-domain filters use the large-signal exponential current-voltage relationship of the bipolar junction transistor to convert signals to logarithmic form, where they are processed, and to map them back to the linear domain after processing. Due to their internally nonlinear nature, application of standard linear circuit design techniques to such networks can give rise to unexpected externally nonlinear behavior. Methods of nonlinear dynamics are used here to explain the undesired nonlinearities recently observed in a differential first-order log-domain integrator and to investigate the input/output behavior of the corresponding low-pass filter. The nonlinear behavior of a floating-capacitor differential second-order log-domain bandpass filter is also investigated and explained.