HSP50214BVIZ Intersil, HSP50214BVIZ Datasheet - Page 22

• Manufacturer Part Number: HSP50214BVIZ
• Description: IC DOWNCONVERTER 14BIT 120-MQFP
• Manufacturer: Intersil

Specifications of HSP50214BVIZ

• Function: Downconverter
• Rf Type: AMPS, CDMA, GSM, TDMA
• Package / Case: 120-MQFP, 120-PQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AGC Gain Limit
(
the AGC THRESHOLD value (Control Word 8, Bits 16-28) is
shown in Table 5. Note that the MSB is always zero. The range
of the AGC THRESHOLD value is 0 to +3.9995. The AGC
Error Detector output has the identical range.
The loop gain is set in the AGC Error Scaling circuitry, using
the two programmable mantissas and exponents. The
mantissa, M, is a 4-bit value which weights the loop filter
input from 0.0 to 0.9375. The exponent, E, defines a shift
factor that provides additional weighting from 2
Together the mantissa and exponent define the loop gain as
given by,
where M
E
8 detail the binary values and th
the AGC scaling mantissa and exponent. The composite
(shifter and multiplier) AGC scaling Gain range is from
0.0000 to 2.329(0.9375)
gain error can range (depending on threshold) from 0 to
2.18344, which maps to a “gain change per sample” range of
0 to 3.275dB/sample.
The AGC Gain mantissa and exponent values are
programmed into Control Word 8, Bits 0-15. The PDC
provides for the storing of two values of AGC Scaling Gain
(both exponent and mantissa). This allows for quick
adjustment of the loop gain by simply asserting the external
control line AGCGNSEL. When AGCGNSEL = 0, then AGC
GAIN 0 is selected, and when AGCGNSEL = 1, AGC Loop
Gain 1 is selected. Possible applications include
acquisition/tracking, no burst present/burst present, strong
signal/weak signal, track/hold, or fast/slow AGC values.
The AGC loop filter consists of an accumulator with a built in
limiting function. The maximum and minimum AGC gain
limits are provided to keep the gain within a specified range
and are programed by 12-bit Control Words using Equation 17:
where m is an 8-bit mantissa value between 0 and 255, and e
is the 4-bit exponent ranging from 0 to 15. Control Word 9,
Bits 16-27 are used for programming the upper limit, while bits
0-11 are used to program the lower threshold. The ranges and
format for these limit values are shown in Tables 6A through
6C. The bit weightings for the AGC Loop Feedback elements
are detailed in Table 9A.
AGC Loop Gain
AGC Gain Limit
28
2
LG
2
TABLE 5. AGC THRESHOLD (CONTROL WORD 8) BIT
is a 4-bit binary value ranging from 0 to 15. Table 7 and
27
2
1
LG
2
26
0
is a 4-bit binary value ranging from 0 to 15, and
.
WEIGHTING
=
)dB = 6.02
2
25
=
-1
(
1
M
+
2
24
LG
(
-2
m
2
AGC
–
2
2
23
4
) eeee
-3
0
(
2
= 0.0000 to 2.18344. The scaled
2
–
–
22
2
(
22
9
15 E
-4
)2
e
)
–
e
+
2
resulting scaling effects of
21
-5
LG
20
)
log
2
20
-6
(
1.0
2
19
-7
+
0.mmmmmmmm
0
2
18
-8
to 2
(EQ. 17A)
2
17
-15
(EQ. 16)
-9
(EQ. 17)
.
2
HSP50214B
16
-10
)
GAIN(dB)
GAIN(dB)
96.332
90.309
84.288
78.268
72.247
66.227
60.206
54.185
48.165
42.144
36.124
30.103
24.082
18.062
12.041
6.021
0.000
6.000
5.750
5.500
5.250
5.000
4.750
4.500
4.250
4.000
3.750
3.500
3.250
3.000
2.750
2.500
2.250
2.000
1.750
1.500
1.250
1.000
0.750
0.500
0.250
0.020
TABLE 6A. AGC LIMIT EXPONENT vs GAIN
TABLE 6B. AGC LIMIT MANTISSA vs GAIN
EXPONENT
EXPONENT
15
15
14
13
12
10
11
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
MANTISSA
MANTISSA
255
255
240
226
212
199
185
173
161
149
138
127
105
116
95
85
75
66
57
48
39
31
23
15
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
7
1
May 1, 2007
FN4450.4