By setting the cutoff frequency of the programmable digital low-pass filter

Posted on Mar 28, 2007

As can be seen from the circuit loop, the circuit is mainly two times a Butterworth filter, in order to make a 0.707, magnification feedback amplifier d was d 3- (1/Q) 1. 5860

By setting the cutoff frequency of the programmable digital low-pass filter
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input amplifier a differential input type, but also to one input is grounded, with only one input terminal, and wherein attenuation filter gain should amount (I.58 6-fold) are equal, in order to ensure that the passband gain of OdB. Feedback resistor Rs is 63k92 (Rs I00 kO 1. 568 63kQ), take the closest series resistance is 62 kC20 on the frequency setting resistor set -: mouth i.Ca using readily available 0,1 F capacitor, according to the lowest frequency (ie, the cutoff frequency of each file) calculation chu. When, 10Hz, the ugly. 1 only stone 0 * 1 l0-ox 10 159. 2kQ}, 20Hz time, Ro 159,2kC) xl/2 79.6k O, 40 Hz, the clamor. 39, 8kQ, increments every two times, said o reduces 1/2 0 if the lowest frequency, whichever is 30Hz, and ugly as the work level, alum was 53. 33kQo by setting L ~ 1 of 5 data, you can make the change in the cut-off frequency fc] O ~ isOHz range. Due to a series of on-resistance analog switch, in order to minimize errors, R. With a high resistance, minimum resistance to 20kQ, assuming that r. - 500, cut-off frequency lower than the calculated value of 0.25%, the election is practically permissible. The circuit of each file by frequency IOHz, if each file up-iOOH ztCL.g Wang capacity should be changed to 0. OILiFo

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