ADS5294 datasheet(55/67 Pages) TI1

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Input Signal Frequency (MHz)

K=2

K=3

K=4

K=5

K=6

K=7

K=8

K=9

K=10

y(n) =

[x(n) x(n 1)+y(n 1)]

2 +1

ADS5294

www.ti.com

SLAS776B – NOVEMBER 2011 – REVISED JULY 2012

DIGITAL HIGH PASS IIR FILTER

DC offset is often observed at ADC input signals. For example, in ultrasound applications, the DC offset from

VGA (variable Gain amplifier) varies at different gains. Such a variable offset can introduce artifacts in ultrasound

images especially in Doppler modes. Analog filter between ADC and VGA can be used with added noise and

power. Digital filter achieves the same performance as analog filters and has more flexibility in fine tuning

multiple characteristics.

ADS5294 includes optional 1st order digital high-pass IIR filter. Its block diagram is shown in Figure 60 as well as

its transfer function

(6)

Figure 60. HP Filter Block Diagram

Figure 61 shows its characteristics at k=2 to 10.

Figure 61. HP Filter Amplitude Response at K = 2 to 10

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