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| 型号： | HSP50214BVCZ |
| 厂商： | Intersil |
| 文件页数： | 21/62页 |
| 文件大小： | 0K |
| 描述： | IC DOWNCONVERTER 14BIT 120-MQFP |
| 标准包装： | 24 |
| 功能： | 降频器 |
| RF 型： | AMPS，CDMA，GSM，TDMA |
| 封装/外壳： | 120-BQFP |
| 包装： | 托盘 |
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HSP50214B
output section. Without gain control, a signal at -72dBFS =
20log 10 (2 -12 ) at the input would have only 4-bits of
resolution at the output (12-bits less than the full scale
16-bits). The potential increase in the bit resolution due to
6
5
processing gain of the filters can be lost without the use of
the AGC.
4
G (dB)
3
Figure 23 shows the Block Diagram for the AGC Section.
The FIR filter data output is routed to the Resampling and
Halfband filters after passing through the AGC multipliers
and Shift Registers. The outputs of the Interpolating
Halfband filters are routed to the Cartesian to Polar
2
1
G (LINEAR)
coordinate converter. The magnitude output of the
coordinate converter is routed through the AGC error
detector, the AGC error scaler and into the AGC loop filter.
0
0
16 32 48 64 80 96 112 128 144 160 176 192 208 224 240
AGC CONTROL MANTISSA VALUES (TIMES 256)
This filtered error term is used to drive the AGC multiplier
and shifters, completing the AGC control loop.
The AGC Multiplier/Shifter portion of the AGC is identified in
FIGURE 21. AGC MULTIPLIER LINEAR AND dB TRANSFER
FUNCTION
Figure 23. The gain control from the AGC loop filter is
sampled when new data enters the Multiplier/Shifter. The
limit detector detects overflow in the shifter or the multiplier
and saturates the output of I and Q data paths
independently. The shifter has a gain from 0 to 90.31dB in
6.021dB steps, where 90.31dB = 20log 10 (2 N ), when N = 15.
The mantissa provides an additional 6dB of gain in
0.0338dB steps where 6.0204dB = 20log 10 [1+(X)2 -15 ],
where X = 2 15 -1. Thus, the AGC multiplier/shifter transfer
function is expressed as:
100
90
80
70
60
50
N = 15
N = 14
N = 13
N = 12
N = 11
N = 10
N=9
N=8
N=7
AGC Mult/Shift Gain = 2 [ 1 + ( X ) 2
N
– 15
] ,
(EQ. 14)
40
N=6
N=5
where N, the shifter exponent, has a range of 0<N<15 and X,
the mantissa, has a range of 0<X<(2 15 -1).
Equation 14 can be expressed in dB,
30
20
10
N=4
N=3
N=2
N=1
(AGC Mult/Shift Gain)dB = 20log 10 ( 2 [ 1 + ( X ) 2
N
-15
] )
(EQ. 14A)
0
0
64
N=0
128
192
The full AGC range of the Multiplier/Shifter is from 0 to
96.331dB (20log 10 [1+(2 15 -1)2 -15 ] + 20log 10 [2 15 ] = 96.331).
Figure 21 illustrates the transfer function of the AGC
multiplier versus mantissa control for N = 0. Figure 22
illustrates the complete AGC Multiplier/Shifter Transfer
function for all values of exponent and mantissa control.
AGC CONTROL WORD (MANTISSA x 256)
FIGURE 22. AGC GAIN CONTROL TRANSFER FUNCTION
The Cartesian to Polar Coordinate converter accepts I and Q
data and generates magnitude and phase data. The
magnitude output is determined by the Equation 15:
The resolution of the mantissa was increased to 16-bits in
the A Version, to provide a theoretical AM modulation level
2 2
r = 1.64676 I + Q .
(EQ. 15)
of -96dBc (depending on loop gain, settling mode and SNR).
This effectively eliminates AM spurious caused by the AGC
resolution.
For fixed gains, either set the upper and lower AGC limits to
where the magnitude limits are determined by the maximum
I and Q signal levels into the Cartesian to Polar converter.
Taking fractional 2’s complement representation, magnitude
ranges from 0 to 2.329, where the maximum output is
r = 1.64676 ( 1.0 ) + ( 1.0 )
the same value, or set the limits to minimum and maximum
gains and set the AGC loop gain to zero.
2
2
= 1.64676 × 1.414 = 2.329 .
The AGC loop feedback path consists of an error detector, error
scaling, and an AGC loop filter. The error detector subtracts the
magnitude output of the coordinate converter from the
programmable AGC THRESHOLD value. The bit weighting of
21
FN4450.4
May 1, 2007
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相关代理商/技术参数 |
参数描述 |
|---|---|
| HSP50214BVI | 功能描述:上下转换器 120L MQFP INDTEMP 14-BIT PROGRAMMABLE DOWNCONVERTER 65MSPS RoHS:否 制造商:Texas Instruments 产品:Down Converters 射频:52 MHz to 78 MHz 中频:300 MHz LO频率: 功率增益: P1dB: 工作电源电压:1.8 V, 3.3 V 工作电源电流:120 mA 最大功率耗散:1 W 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PQFP-128 |
| HSP50214BVIZ | 功能描述:上下转换器 120L MQFP INDTEMP 14-BIT PROG DWNCNVRT RoHS:否 制造商:Texas Instruments 产品:Down Converters 射频:52 MHz to 78 MHz 中频:300 MHz LO频率: 功率增益: P1dB: 工作电源电压:1.8 V, 3.3 V 工作电源电流:120 mA 最大功率耗散:1 W 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PQFP-128 |
| HSP50214VC | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| HSP50214VI | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| HSP50215 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:DSP Modulator Evaluation Board |
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