AD6652BC/PCB Analog Devices Inc, AD6652BC/PCB Datasheet - Page 39

• Manufacturer Part Number: AD6652BC/PCB
• Description: BOARD EVAL W/AD6652 & SOFTWARE
• Manufacturer: Analog Devices Inc

Specifications of AD6652BC/PCB

• Module/board Type: Evaluation Board
• For Use With/related Products: AD6652
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

RCF OUTPUT SCALE FACTOR AND CONTROL
REGISTER
Register 0xA4 is a compound register used to configure several
aspects of the RCF register. Use Bits 3–0 to set the scale of the
fixed-point output mode. This scale value can also be used to
set the floating-point outputs in conjunction with Bit 6 of this
register.
Bits 4 and 5 determine the output mo . Mode 00 sets the chip
up in fixed-point mode. The number f bits is determined by
the seria
Mo e 01 selects floating-point mode 8 +
8-bit mantissa is followed by a 4-bit exponent. In mode 1x
don’t care), the mode is 12 + 4, or 12-bit mantissa and 4-bi
exponent.
Table 17.
Format
Floating Point 12 + 4
Floating Point 8 + 4
Fixed Point
Normally, the AD6652 determines the exponent value that
optimizes numerical accuracy. However, if Bit 6 is set, the value
stored in Bits 3–0 is used to scale the output. This ensures
consistent scaling and accuracy during conditions that might
warrant predictable output ranges. If Bits 3–0 are represented by
RCF scale, the scaling factor in dB is given by
d
Scaling
l port configuration.
Output Mode Formats
Factor
=
(
RCF
Scale
Value
1x
01
00
−
) 3
de
o
×
20
4. In this mode, an
log
10
(
) 2
dB
t
(x is
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For an RCF scale of 0, the scaling factor is equal to −18.06 dB,
and for a maximum RCF scale of 15, the scaling factor is equal
to +72.25 dB.
If Bit 7 is set, the same exponent is used for both the real and
imagina
prevents numeric overflow at the expense of small signal
accuracy. However, this is seldo
numbers would represent 0 regardless of the exponent used.
Bit 8 is the RCF bank select bit used to program the register.
When this bit is 0, the lowest block of 128 is selected (taps 0 to
127). When high, the highest block is selected (taps 128 to 255).
It should be
Tap 127 is adjacent to Tap 128 and there are no paging issues.
Bit 9 selects where the input to each RCF originates. If Bit 9 is
clear, then the RCF input comes from the CIC5 normally
associated with the RCF. However, if the bit is set, then the in
comes from CIC5 Channel 1. The only exception is Channel 1,
which uses the output of CIC5 Channel 0 as its alternate. Using
this feature, each RCF can either operate on its own channe
data or be paired with the RCF of Channel 1. The RCF of
Chann
used with polyphase distributed filtering.
If Bit 10 is clear, the AD6
However, if Bit 10 is set, then the RCF is bypassed to Channel
BIST ee the User-Configurable Built-In Self-Test (BIST)
section for more details.
. S
el 1 can also be paired with Channel 0. This control bit is
ry (I and Q) outputs. The exponent used is the one that
noted that while the chip is computing filters,
652 channel operates in normal mode.
m a problem, because small
AD6652
l
put