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參數資料
| 型號： | AD9948 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 10-Bit CCD Signal Processor with Precision Timing⑩ Core |
| 中文描述： | 10位CCD信號處理器核心精確定時⑩ |
| 文件頁數： | 23/28頁 |
| 文件大小： | 539K |
| 代理商： | AD9948 |
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REV. 0
AD9948
–23–
The PxGA gain for each of the four channels is variable from 0 dB
to 18 dB in 512 steps, specified using the PxGA GAIN01 and
PxGA GAIN23 registers. The PxGA gain curve is shown in
Figure 19. The PxGA GAIN01 registers contains nine bits each
for PxGA Gain0 and Gain1, and the PxGA GAIN23 registers
contains nine bits each for PxGA Gain2 and Gain3.
PxGA GAIN REGISTER CODE
18
0
P
64
128
192
256
320
384
448
511
15
12
9
6
3
0
Figure 19. PxGA Gain Curve
Variable Gain Amplifier
The VGA stage provides a gain range of 6 dB to 42 dB, program-
mable with 10-bit resolution through the serial digital interface.
The minimum gain of 6 dB is needed to match a 1 V input signal
with the ADC full-scale range of 2 V. When compared to 1 V
full-scale systems, the equivalent gain range is 0 dB to 36 dB.
The VGA gain curve follows a linear-in-dB characteristic. The
exact VGA gain can be calculated for any gain register value by
using the equation
(
)
(0 0351
=
Gain dB
Code
dB
)
×
+
6
where the code range is 0 to 1023.
There is a restriction on the maximum amount of gain that can
be applied to the signal. The PxGA can add as much as 18 dB,
and the VGA is capable of providing up to 42 dB. However, the
maximum total gain from the PxGA and VGA is restricted to
42 dB. If the registers are programmed to specify a total gain
higher than 42 dB, the total gain will be clipped at 42 dB.
VGA GAIN REGISTER CODE
42
0
V
127
255
383
511
639
767
895
1023
36
30
24
18
12
6
Figure 20. VGA Gain Curve (PxGA Not Included)
A/D Converter
The AD9948 uses a high performance ADC architecture, opti-
mized for high speed and low power. Differential nonlinearity
(DNL) performance is typically better than 0.5 LSB. The ADC
uses a 2 V input range. See TPC 1 and TPC 2 for typical linearity
and noise performance plots for the AD9948.
Optical Black Clamp
The optical black clamp loop is used to remove residual offsets
in the signal chain and to track low frequency variations in the
CCD’s black level. During the optical black (shielded) pixel
interval on each line, the ADC output is compared with a fixed
black level reference, selected by the user in the clamp level register.
The value can be programmed between 0 LSB and 63.75 LSB
in 256 steps. The resulting error signal is filtered to reduce noise,
and the correction value is applied to the ADC input through a
D/A converter. Normally, the optical black clamp loop is turned
on once per horizontal line, but this loop can be updated more
slowly to suit a particular application. If external digital clamping
is used during the postprocessing, the AD9948 optical black
clamping may be disabled using Bit D2 in the OPRMODE register.
When the loop is disabled, the clamp level register may still be
used to provide programmable offset adjustment.
The CLPOB pulse should be placed during the CCD’s optical
black pixels. It is recommended that the CLPOB pulse duration
be at least 20 pixels wide to minimize clamp noise. Shorter
pulsewidths may be used, but clamp noise may increase and the
ability to track low frequency variations in the black level will be
reduced. See the Horizontal Clamping and Blanking and the
Applications Information sections for timing examples.
Digital Data Outputs
The AD9948 digital output data is latched using the DOUT
phase register value, as shown in Figure 15. Output data timing is
shown in Figure 7. It is also possible to leave the output latches
transparent, so that the data outputs are valid immediately from
the A/D converter. Programming the AFE control register Bit D4
to a 1 will set the output latches transparent. The data outputs
can also be disabled (three-stated) by setting the AFE control
register Bit D3 to a 1.
The data output coding is normally straight binary, but the
coding my be changed to gray coding by setting the AFE
control register Bit D5 to a 1.
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| AD9948KCP | 10-Bit CCD Signal Processor with Precision Timing⑩ Core |
| AD9948KCPRL | 10-Bit CCD Signal Processor with Precision Timing⑩ Core |
| AD9949KCP | 12-Bit CCD Signal Processor with Precision Timing Core |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| AD9948AKCPZ | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Analog Devices 功能描述: |
| AD9948AKCPZRL | 制造商:Analog Devices 功能描述: |
| AD9948KCP | 制造商:Rochester Electronics LLC 功能描述:10 BIT 25 MSPS, 3V ANALOG FRONT END - Bulk 制造商:Analog Devices 功能描述: |
| AD9948KCPRL | 制造商:Rochester Electronics LLC 功能描述:10 BIT 25 MSPS, 3V ANALOG FRONT END - Bulk 制造商:Analog Devices 功能描述: |
| AD9948KCPZ | 功能描述:IC CCD SIGNAL PROCESSOR 40-LFCSP RoHS:是 類別:集成電路 (IC) >> 接口 - 傳感器和探測器接口 系列:- 其它有關文件:Automotive Product Guide 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:74 系列:- 類型:觸控式傳感器 輸入類型:數字 輸出類型:數字 接口:JTAG，串行 電流 - 電源:100µA 安裝類型:表面貼裝 封裝/外殼:20-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:20-TSSOP 包裝:管件 |
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