Electronic systems Essay Example | Topics and Well Written Essays - 2750 words

Electronic systems - Essay Example These filters produce gain and usually consist only of resistors, capacitors and operational amplifiers. The most common classes of filters that can either be passive or active are the low pass, high pass, band pass, and band stop filters. Ideal low pass filters allow frequencies up to a given limit to pass and attenuate frequencies above that limit. Ideal high pass filters on the other hand, pass frequencies above a specified limit and attenuate those below. Ideal band pass filters allow only a particular band of frequencies to pass and attenuate the remaining frequencies. Ideal band stop filters are the reverse; this class of filters rejects frequencies within a specified band and passes those frequencies outside it. The figure below can be interpreted as first order active filters connected in series. By cascading a 20 dB-gain first order bi-linear filter and another first order bi-linear filter with unity-gain, we can construct a low pass filter whose frequency response is that in Figure 1. When universal filters are cascaded, they form a shaped filter. It is specified that the output signal MUST NOT BE INVERTED. Notice that the transfer function of a bi-linear filter includes a NEGATIVE sign. When two bi-linear filters are cascaded, this eliminates the negative sign thus there is NO NEED for an inverter. From the Transfer Function, where ω denotes the cut-off RADIAN frequency, we can get the cut-off frequency. Since the radian frequency ω =2πf then, . When ω is at the numerator, it denotes a zero and if it is a the denominator, it denotes a pole. A filter is designed based on a given transfer characteristic. An active low pass filter with a gain of 20dB below 10 Hz, 0 dB gain from 160Hz to 48 kHz and -20 dB attenuation above 500 kHz is the subject of this paper. This filter is composed of cascaded components. The transfer characteristic of each of these components is multiplied to obtain the transfer function of the low pass filter. The