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參數(shù)資料
| 型號(hào)： | CLC5903 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Dual Digital Tuner / AGC |
| 中文描述： | 雙數(shù)字調(diào)諧器/自動(dòng)增益控制 |
| 文件頁數(shù)： | 15/29頁 |
| 文件大小： | 698K |
| 代理商： | CLC5903 |
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C
mum headroom through the CIC filter. For optimal noise per-
formance the SCALE value is set to increase this level until
the CIC filter is just below the point of distortion. A value is
normally calculated and loaded for SCALE such that
GAIN
SHIFTUP
GAIN
CIC
1
. The actual gain of the CIC
filter will only be unity for power-of-two decimation values. In
other cases the gain will be somewhat less than unity.
Channel Gain
The gain of each channel can be boosted up to 42 dB by
shifting the output of the CIC filter up by 0 to 7 bits prior to
rounding it to 21 bits. For channel A, the gain of this stage is:
2
GAIN_A
=
, where GAIN_A ranges from 0 to 7. Over-
flow due to the GAIN circuit is saturated (clipped) at plus or
minus full scale. Each channel can be given its own GAIN
setting.
First Programmable FIR Filter (F1)
The CIC/GAIN outputs are followed by two stages of filtering.
The first stage is a 21 tap decimate-by-2 symmetric FIR filter
with programmable coefficients. Typically, this filter compen-
sates for a slight droop induced by the CIC filter while remov-
ing undesired alias images above Nyquist. In addition, it
often provides stopband assistance to F2 when deep stop
bands are required. The filter coefficients are 16-bit 2’s com-
plement numbers. Unity gain will be achieved through the fil-
ter if the sum of the 21 coefficients is equal to 2
16
. If the sum
is not 2
16
, then F1 will introduce a gain equal to (sum of coef-
ficients)/2
16
. The 21 coefficients are identified as coefficients
where
coefficients are symmetric, so only the first 11 are loaded
into the chip.
Two example sets of coefficients are provided here. The first
set of coefficients, referred to as the standard set (STD),
compensates for the droop of the CIC filter providing a pass-
band which is flat (0.01 dB ripple) over 95% of the final out-
put bandwidth with 70dB of out-of-band rejection (see Figure
21). The filter has a gain of 0.999 and is symmetric with the
following 11 unique taps (1|21, 2|20, ..., 10|12, 11):
29, -85, -308, -56, 1068, 1405, -2056, -6009,
1303, 21121, 32703
is the center tap. The
The second set of coefficients (GSM set) are intended for
applications that need deeper stop bands or need oversam-
pled outputs. These requirements are common in cellular
systems where out of band rejection requirements can
exceed 100dB (see Figure 22). They are useful for wideband
radio architectures where the channelization is done after the
ADC. These filter coefficients introduce a gain of 0.984 and
are:
-49, -340, -1008, -1617, -1269, 425, 3027, 6030,
9115, 11620, 12606
Second Programmable FIR Filter (F2)
The second stage decimate by two or four filter also uses
externally downloaded filter coefficients. F2 determines the
final channel filter response. The filter coefficients are 16-bit
2’s complement numbers. Unity gain will be achieved through
the filter if the sum of the 63 coefficients is equal to 2
16
. If the
sum is not 2
16
, then the F2 will introduce a gain equal to
(sum of coefficients)/2
16
.
The 63 coefficients are identified as
where
is the center tap. The coefficients are sym-
metric, so only the first 32 are loaded into the chip.
An example filter (STD F2 coefficients, see Figure 23) with
80dB out-of-band rejection, gain of 1.00, and 0.03 dB peak to
peak passband ripple is created by this set of 32 unique
coefficients:
-14, -20, 19, 73, 43, -70, -82, 84, 171, -49, -269,
-34, 374, 192, -449,
-430, 460,751, -357, -1144, 81, 1581, 443, -2026,
-1337, 2437, 2886,
-2770, -6127, 2987, 20544, 29647
A second set of F2 coefficients (GSM set, see Figure 24)
suitable for meeting the stringent wideband GSM require-
ments with a gain of 0.999 are:
-536, -986, 42, 962, 869, 225, 141, 93, -280,
-708, -774, -579, -384,
-79, 536, 1056, 1152, 1067, 789, 32, -935, -1668,
-2104, -2137, -1444,
71, 2130, 4450, 6884, 9053, 10413, 10832
The filter coefficients of both filters can be used to tailor the
spectral response to the user’s needs. For example, the first
can be loaded with the standard set to provide a flat
≤
GAIN
h
1
n
( )
n
,
0
…
20
,
,
=
h
1
10
(
)
Figure 21. F1 STD frequency response
0
0.1
0.2
0.3
0.4
0.5
100
90
80
70
60
50
40
30
20
10
0
Frequency Response of F1 Using STD Set
M
Frequency Normalized To Filter Input Sample Rate
Figure 22. F1 GSM frequency response
0
0.1
0.2
0.3
0.4
0.5
120
100
80
60
40
20
0
Frequency Response of F1 Using GSM Set
M
Frequency Normalized To Filter Input Sample Rate
h
2
n
( )
n
,
0
…
62
,
,
=
h
2
31
(
)
Detailed Description
(Continued)
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| CLC5903SM | Dual Digital Tuner / AGC |
| CLC5903VLA | Dual Digital Tuner / AGC |
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| CLC5955MTDX | 11-bit, 55MSPS Broadband Monolithic A/D Converter |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| CLC5903CISM/NOPB | 功能描述:上下轉(zhuǎn)換器 RoHS:否 制造商:Texas Instruments 產(chǎn)品:Down Converters 射頻:52 MHz to 78 MHz 中頻:300 MHz LO頻率: 功率增益: P1dB: 工作電源電壓:1.8 V, 3.3 V 工作電源電流:120 mA 最大功率耗散:1 W 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFP-128 |
| CLC5903SM | 功能描述:上下轉(zhuǎn)換器 RoHS:否 制造商:Texas Instruments 產(chǎn)品:Down Converters 射頻:52 MHz to 78 MHz 中頻:300 MHz LO頻率: 功率增益: P1dB: 工作電源電壓:1.8 V, 3.3 V 工作電源電流:120 mA 最大功率耗散:1 W 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFP-128 |
| CLC5903SM/NOPB | 功能描述:上下轉(zhuǎn)換器 RoHS:否 制造商:Texas Instruments 產(chǎn)品:Down Converters 射頻:52 MHz to 78 MHz 中頻:300 MHz LO頻率: 功率增益: P1dB: 工作電源電壓:1.8 V, 3.3 V 工作電源電流:120 mA 最大功率耗散:1 W 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFP-128 |
| CLC5903VLA | 功能描述:上下轉(zhuǎn)換器 RoHS:否 制造商:Texas Instruments 產(chǎn)品:Down Converters 射頻:52 MHz to 78 MHz 中頻:300 MHz LO頻率: 功率增益: P1dB: 工作電源電壓:1.8 V, 3.3 V 工作電源電流:120 mA 最大功率耗散:1 W 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFP-128 |
| CLC5903VLA/NOPB | 功能描述:上下轉(zhuǎn)換器 RoHS:否 制造商:Texas Instruments 產(chǎn)品:Down Converters 射頻:52 MHz to 78 MHz 中頻:300 MHz LO頻率: 功率增益: P1dB: 工作電源電壓:1.8 V, 3.3 V 工作電源電流:120 mA 最大功率耗散:1 W 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFP-128 |
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