公开(公告)号：EP0142586A1

公开(公告)日：1985-05-29

申请号：EP83307036.0

申请日：1983-11-17

申请人： BUDAPESTI RADIOTECHNIKAI GYAR

发明人： Kovacs, Sandor ,  Fozo, Arpad

IPC分类号： H03H11/12 ,  H03B5/20

CPC分类号： H03H11/1252 ,  H03B5/20 ,  H03B2200/0064 ,  H03B2200/0066

摘要： An active filter arrangement particularly for the reception and transmission of signal sequences, which comprises three feed back operational amplifiers (1,2,3) connected in a closed loop chain. The feedback impedance of one of the amplifiers (1) comprises an ohmical and a capacitive member connected in parallel, while another (2) is fed back by a capacitive impedance. At least one of the capacitive branches includes an RC member. The quality factor can be changed by the adjustment of the ohmical branch while the frequency can be changed by adjusting the coupling between the operational amplifiers within wide ranges. One of the operational amplifiers comprises a feedback circuit (7) controlled by a pulse width modulator (8) by means of which an oscillator mode of operation can be set and the frequency of oscillation will be that of the filter. The oscillator amplitude can be controlled by means of the pulse width modulator (8).
The adjustment of the frequency and/or the quality factor can be carried out by means of an attenuator comprising a series chain of resistors (Ro to Rn) coupled to an operational amplifier (17) which arrangement is capable of realizing virtual ground potential with discretely changable location in the chain.
The active filter has a preferable field of application in a circuit arrangement for generating and receiving signal sequences in radio transmitter-receiver systems.

摘要翻译： 一种有源滤波器装置，特别用于信号序列的接收和发送，其包括连接在闭环链路中的三个反馈运算放大器（1,2,3）。 放大器（1）中的一个的反馈阻抗包括并联连接的欧姆和电容部件，而另一个（2）由电容性阻抗反馈。 电容分支中的至少一个包括RC构件。 可以通过调整欧姆支路来改变质量因子，同时可以通过调节宽范围内的运算放大器之间的耦合来改变频率。 运算放大器之一包括由脉冲宽度调制器（8）控制的反馈电路（7），通过该电路可以设置振荡器操作模式，并且振荡频率将是滤波器的频率。 振荡器振幅可以通过脉冲宽度调制器（8）来控制。 可以通过包括耦合到运算放大器（17）的一系列电阻器（R0至Rn）的衰减器来执行频率和/或品质因子的调整，该布置能够离散地实现虚拟地电势 在链条中可更换的位置。 有源滤波器在用于在无线电发射机 - 接收机系统中生成和接收信号序列的电路装置中具有优选的应用领域。