数字可编程的电流模式通用双二阶滤波器

本文提出了一种新的基于MOCCII的等电容和等电阻电流模式通用双二阶滤波器综合方法.通过对双二阶通用滤波传输函数进行分析将其分解成能用无损积分器实现的表达式,完成电路综合.该滤波电路包含4个有源器件、8个接地无源元件,通过控制数字可编程开关在输出端得到电流模式二阶低通、高通、带通、带阻和全通五种滤波功能.电路有很低无源灵敏度.文中对滤波器进行了PSPICE模拟验证.     

基于第三代电流传输器的电流模式有源滤波器

提出了由电压模式有源RC滤波器导出基于第三代电流传输器的电流模式滤波器的方法.所得的电流模式二阶滤波器结构简单,能实现二阶低通,高通,带通滤波,不仅所有无源和有源灵敏度都很低,而且当无源参数确定后,有源参数对极点频率不产生影响,保持恒定.HSPICE仿真表明,所提出的电路是可行的.     

Two digitally programmable gain amplifiers based on current conveyors

Two digitally programmable gain amplifiers based on current conveyors (CCIIs) are presented. The first digitally programmable gain amplifier consists of a CCII, an operational transconductance amplifier (OTA), and current mirrors. The second one is composed of current conveyor analogue switches (CCASs). Both proposed digitally programmable gain amplifiers do not need switches but they maintain the linear gain at any digital signal levels similar to the digitally programmable gain amplifier using switches; hence the proposed amplifiers are easier to realize, use narrower chip area, and consume lower power. The first proposed amplifier is verified by constructing the circuit using the CCII in an AD844 IC, the OTA in a CA3080 IC, and some bipolar current mirrors. The second proposed amplifier is verified by simulating the circuit using the parameters extracted from the layout (including parasitic capacitance) in the 0.25 μm MOS technology, the level 49 MOS model obtained through MOSIS is used. The results show that the operations of two proposed amplifiers are in accordance with the theories.     

New electronically tunable current-mode universal biquad filter using translinear current conveyors

In this study, a new electronically tunable current-mode universal filter with two inputs and two outputs employing one translinear current conveyor, one translinear current conveyor with controlled current gain and two grounded capacitors is presented. The proposed circuit offers the following attractive features: realisation of low-pass, band-pass, high-pass, band-stop and all-pass current responses from the same configuration; employment of the minimum active and passive components; no requirement of component matching conditions; independent current-control of the parameters natural frequency (ω_o) and quality factor (Q); low active and passive sensitivities; and high impedance output. The characteristics of the proposed circuit are simulated using PSPICE to confirm the theory.     

Novel versatile insensitive universal current-mode biquad employing two second-generation current conveyors

A new universal current-mode biquad with two inputs and three outputs or three inputs and two outputs using only two second-generation current conveyors and four grounded/virtual-grounded passive elements is proposed. The proposed circuit has the following advantages: simultaneous realization of five generic current-mode filter signals from the same configuration; no requirements of any cancellation constraints; employment of two grounded capacitors ideal for integrated circuit implementation; employment of two grounded/virtually grounded resistors suitable for voltage control; orthogonal adjustment of ω₀/Q and ω₀ through two separate grounded/virtually-grounded resistors; high output impedance good for cascadability for the current-mode circuits; and low active and passive sensitivities.     

KHN-equivalent biquad using current conveyors

A new current-conveyor-based (CC) biquad, equivalent to the well known KHN circuit, is introduced. The proposed circuit employs exactly the same number (five) of CCs and resistors (six/seven) along with two grounded capacitors as in the two CC biquads recently reported by Soliman (see ibid., vol. 30, p. 2019-20, 1994). However, in contrast to Soliman's circuits, the proposed biquad offers several other advantages     

Quadrature oscillator and universal filter based on translinear current conveyors

This paper presents quadrature oscillator and universal filter based on translinear current conveyors. The proposed circuit can realize as a quadrature oscillator or a universal filter without changing the circuit topology. When it works as a quadrature oscillator, four quadrature current outputs and two quadrature voltage outputs can be obtained. The condition and frequency of oscillation of oscillator can be controlled orthogonally and electronically. When it works as a universal filter, low-pass, band-pass, high-stop, band-stop, and all-pass filtering functions can be obtained simultaneously. The natural frequency and quality factor of filters can be controlled orthogonally and electronically. The proposed topology is simulated using PSPICE simulators and experimental results are also used to confirm workability of new circuit.     

A digitally programmable switched-capacitor universal active filter/oscillator

A universal second-order switched-capacitor filter section has been fabricated on an NMOS chip. The device can perform all five basic filter types as well as a sine wave oscillator without external components, while requiring only an external clock. The filter type is determined by selecting one or more of three input pins. The filter response is determined by ten external programming pins which may be either digitally controlled or hard wired.     

A systematic realization of current mode universal biquad filters

A family of current mode universal biquads has been proposed. The biquad filters employ multiple output floating nullor (MOFN) configured as multiple output current conveyors (MOCC). The five-MOFN-based biquad has the property of independently tunable gain, bandwidth, and cut-off frequency without having any passive component matching constraint. Although the four/three MOFN-based universal biquads offer limited tunability of different parameters they do not have any parameter matching constraint on them and in addition, they offer the advantage of reduction in the number of MOFNs and resistances. The workability of all the proposed circuits has been verified using PSPICE simulations based CMOS MOFNs implemented in 0.35?µ CMOS technology.     

基于现场可编程门阵列的数控延时器的设计

给出一种基于现场可编程门阵列(FPGA)的数控延时器的设计方法.首先详细介绍使用计数器的串联实现可控延时的方法,接着讨论不同延时范围下该数控延时器的改进方案,最后分析延时误差及延时精确度.延时器的外部接口仿照AD9501设计.     

Insensitive current-mode universal filter using dual output current conveyors

A new current-mode universal filter with single input and three outputs employing only three dual output current conveyors and five grounded passive elements is presented. The proposed filter realizes three filter functions simultaneously, all at high impedance outputs. No component matching is required and all the passive and active sensitivities are low. Furthermore, the filter can also realize the notch and all-pass responses. Orthogonal control of the natural angular frequency and the quality factor is achieved.