GC1115 Datasheet, PDF (63/80 Pages) Texas Instruments – Crest Factor Reduction Processor

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GC1115
SLWS144 – FEBRUARY 2005
OUT_GAIN0
0xF3 (243) Type: Read/Write Value at RESET: 0x0000
The OUT_GAIN0 register contains the OUT_A output gain. Under normal circumstances, the microprocessor or
DSP should initialize OUT_GAIN0 to 0x2000, which corresponds to a normalized gain of 1.0. OUT_GAIN0 can
provide up to two bits of boost: an OUT_GAIN0 value of 0x3FFF corresponds to a normalized gain of 3.999939.
OUT_GAIN0 is a signed value, so negative OUT_GAIN0 values are permitted. Users should be aware that a
negative OUT_GAIN0 value would cause a 180-degree phase inversion of the OUT_A output signal.
The default OUT_GAIN0 value is 0, so the GC1115 will output zeros at RESET. In order to generate non-zero
GC1115 output values, OUT_GAIN0 and OUT_GAIN1 must be set to non-zero values (preferably 0x2000,
which equates to 1.0). OUT_GAIN0 and OUT_GAIN1 must be written by the microprocessor or DSP, or
the OUT_A and OUT_B will always output zeros.
BITS
[14:0]
15
Output Port A gain (2 MSBs are
GAIN bits):
Output gain sign bit:
DESCRIPTION
0x7FFF = gain of
3.999939
0x4000 = gain of 2.0
0x2000 = gain of 1.0 0x1FFF = gain of 0.999893
0x0000 = gain of 0.0 (zeros are output)
0 = positive gain
1 = negative gain
OUT_GAIN1
0xF4 (244)
Type: Read/Write
Value at RESET: 0x0000
The OUT_GAIN1 register contains the OUT_B output gain. Under normal circumstances, the microprocessor or
DSP should initialize OUT_GAIN1 to 0x2000, which corresponds to a normalized gain of 1.0. OUT_GAIN1 can
provide up to two bits of boost; an OUT_GAIN1 value of 0x3FFF corresponds to a normalized gain of 3.999939.
OUT_GAIN1 is a signed value, so negative OUT_GAIN1 values are permitted. Users should be aware that a
negative OUT_GAIN1 value would cause a 180-degree phase inversion of the OUT_B output signal.
The default OUT_GAIN1 value is 0, so the GC1115 will output zeros at RESET. In order to generate non-zero
GC1115 output values, OUT_GAIN0 and OUT_GAIN1 must be set to non-zero values (preferably 0x2000,
which equates to 1.0). OUT_GAIN0 and OUT_GAIN1 must be written by the microprocessor or DSP, or
the OUT_A and OUT_B will always output zeros.
BITS
[14:0]
15
Output Port B gain (2 MSBs are
GAIN bits):
Output gain sign bit:
DESCRIPTION
0x7FFF = gain of
3.999939
0x4000 = gain of 2.0
0x2000 = gain of 1.0
0x1FFF = gain of 0.999893
0x0000 = gain of 0.0 (zeros are output)
0 = positive gain
1 = negative gain
OUT_OFFSET_I0 0xF5 (245) Type: Read/Write Value at RESET: 0x0000
The OUT_OFFSET_I0 register contains the OUT_A offset value for the I0 channel. In one-channel operation, I0
is the I-channel offset. OUT_OFFSET register values are signed, 16-bit values that are aligned with the 16 MSBs
of the 18-bit signed I-channel sample. OUT_OFFSET_I0 is also the Channel 0 offset applied to the real output
samples in real-output modes (i.e. when the interpolate block is generating 2x real or 4x real samples).
BITS
[15:0]
DESCRIPTION
Channel 0, I leg DC offset (also the Channel 0 real offset in real output mode)
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