AFE7222_15 Datasheet, PDF (28/106 Pages) Texas Instruments – Analog Front End Wideband Mixed-Signal Transceiver

AFE7222
AFE7225
SLOS711B – NOVEMBER 2011 – REVISED MARCH 2012
www.ti.com
Register Name – CONFIG18 – Address 0x117 Default = 0x00 (Synced)
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
TX_NCO_FREQ_WORD(31:24)
TX_NCO_FREQ_WORD(31:24) – See CONFIG21 below.
Register Name – CONFIG19 – Address 0x118 Default = 0x00 (Synced)
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
TX_NCO_FREQ_WORD(23:16)
TX_NCO_FREQ_WORD(23:16) – See CONFIG21 below.
Register Name – CONFIG20 – Address 0x119 Default = 0x00 (Synced)
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
TX_NCO_FREQ_WORD(15:8)
TX_NCO_FREQ_WORD(15:8) – See CONFIG21 below.
Register Name – CONFIG21 – Address 0x11A Default = 0x00 (Synced)
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
TX_NCO_FREQ_WORD(7:0)
TX_NCO_FREQ_WORD(7:0) – This is used to determine the frequency, F_mix of the NCO. The twos
complement formatted value can be positive or negative, and the LSB is equal to Fs/2³²
Register Name – CONFIG22 – Address 0x11B Default = 0x00 (Synced)
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
TX_NCO_PHASE_OFF(15:8)
TX_NCO_FREQ_WORD(15:8) – See CONFIG23 below.
Register Name – CONFIG23 – Address 0x11C Default = 0x00 (Synced)
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
TX_NCO_PHASE_OFF(7:0)
TX_NCO_PHASE_OFF(7:0) – This is the 2s complement Phase offset added to the NCO accumulator
just before the generation of the SIN and COS values.
Register Name – CONFIG24 – Address 0x11D, Default = 0x00
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
TX_MIXER_EN
TX_MIXER_GAIN(1:0)
TX_MIXER_GAIN(1:0) – The fine mixer realizes the functions {Acos(ω_mixt) – B sin(ω_mixt)} and {Asin(ω_mixt)
+ Bcos(ω_mixt)} This can cause the fine mixer output to be up to 3 dB higher than the individual inputs.The
mixer gain can restore the signal level to the desired level by providing a programmable attenuation.
VALUE
0
1
2
3
GAIN
–2.5 dB (default) – use when complex mixing
–6 dB
0 dB – use when one input is zero
0 dB
TX_MIXER_EN – This enables the fine mixer, which also causes the NCO to be enabled.
28
REGISTER DESCRIPTIONS
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