Datasheet

1 2
0 1 2
15 1 2
1 2
N 2 N z N z
H(z)
2 2 D z D z
- -
- -
+ ´ +
=
- ´ -
1
0 1
15 1
1
N N z
H(z)
2 D z
-
-
+
=
-
LargestPositiveNumber:
=0.111 1111 1111 111
=0.999969482421875=1.0 – 1LSB
1
LargestNegativeNumber:
=1.0000 0000 0000 000
=0x8000= –1.0(bydefinition)
1 1 1
1 1 1
S.xxxx xxxx xxxx xxx.. x x x
SignBit
2 Bit
–1
2 Bit
–4
2 Bit
–15
Fraction
Point
TLV320AIC3110
www.ti.com SLAS647B –DECEMBER 2009–REVISED MAY 2012
The coefficients of these filters are each 16 bits wide, in 2s-complement format, and occupy two
consecutive 8-bit registers in the register space. Specifically, the filter coefficients are in 1.15 (one dot 15)
format with a range from –1.0 (0x8000) to 0.999969482421875 (0x7FFF), as shown in Figure 5-12.
Figure 5-12. 1.15 2s-Complement Coefficient Format
5.4.4.3.1 First-Order IIR Section
The transfer function for the first-order IIR filter is given by
(1)
The frequency response for the first-order IIR section with default coefficients is flat at a gain of 0 dB.
Table 5-18. ADC First-Order IIR Filter Coefficients
Filter
Filter ADC Coefficient Default (Reset) Values
Coefficient
N0 Page 4 / register 8 and 0x7FFF (decimal 1.0 – LSB value)
page 4 / register 9
N1 Page 4 / register 10 and 0x0000
First-order IIR
page 4 / register 11
D1 Page 4 / register 12 and 0x0000
page 4 / register 13
5.4.4.3.2 Biquad Section
The transfer function of each of the biquad filters is given by
(2)
The default values for each biquad section yield an all-pass (flat) frequency response at a gain of 0 dB.
Copyright © 2009–2012, Texas Instruments Incorporated APPLICATION INFORMATION 33
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