■ PSKEY_SIDE_TONE_ENABLE
■ PSKEY_SIDE_TONE_GAIN
■ PSKEY_SIDE_TONE_AFTER_ADC
■ PSKEY_SIDE_TONE_AFTER_DAC
9.2.18 Integrated Digital IIR Filter
CSR8635 QFN has a programmable digital filter integrated into the ADC channel of the codec. The filter is a 2-stage,
second order IIR and is for functions such as custom wind noise reduction. The filter also has optional DC blocking.
The filter has 10 configuration words:
■ 1 for gain value
■ 8 for coefficient values
fNCTEToFohhoqlolteeduoeraew:■TfgeitclaihixtnoeSieangnrem1p9oiatsop.rnfI1doslcdeIierost:Ricrneho:FofnonieiPgawoflurbfsefirtlciettpneihhedagreen,rBateeebsnnqditnradauaafrbaopderltyrsieisao.qdpalnTliobna1fhilognni2insrdbt-gtbiorhsdeitteihkqbs000112eeIaueI'11010svRbitDrw.....eleceCf10000ensiodl10000et.mbefz10000nfilrrrhpo10000mo.bolcE10000meiwuktm10000q[ia1ntu10000-her0ga10000eeen]t10000xtiasVoc10000012345678sunnMeipdgl9=====:::::::::ppnvb.ooe2iiat10--mGbbaabbardi[nst9000011112.taohti1212121h]nT,.i,socnetmhtwweoeCpgomhsooescet.sdthrorcieneenwtnievcfbeii-teggSihqtaFu[eun1ttrrthauia1ivdeItmt]eiiaoIoifbsnyonnRe,urtFfmrfhomSu,ieranceblwtlcmpeottNhtrsieoeoeNesrmnn.tAtNottbsahaNieg2kenNrendDN2sifNCi7c1N,a0bN2nlvoN0tacNb1rkNi3itian..bgleisseinnathbeled.
9 : a12
DC Block (1 = enable, 0 = disable)
Filter, H(z)
=
Gain
×
(1
(1
+ b01
+ a01
z−1
z−1
+ b02
+ a02
z−2
z−2
)
)
×
(1
(1
+ b11
+ a11
z−1
z−1
+ b12 z−2 )
+ a12 z−2 )
Equation 9.1: IIR Filter Transfer Function, H(z)
Filter with DC Blocking, HDC (z) = H(z) × ( 1 − z−1 )
Equation 9.2: IIR Filter Plus DC Blocking Transfer Function, HDC(z)
Production Information
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Confidential Information - This Material is Subject to CSR's Non-disclosure Agreement
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