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| 型號： | AD8012ARM |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 7/17頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC OPAMP CF DUAL LP 125MA 8MSOP |
| 標(biāo)準(zhǔn)包裝： | 50 |
| 放大器類型： | 電流反饋 |
| 電路數(shù)： | 2 |
| 轉(zhuǎn)換速率： | 2250 V/µs |
| -3db帶寬： | 350MHz |
| 電流 - 輸入偏壓： | 3µA |
| 電壓 - 輸入偏移： | 1500µV |
| 電流 - 電源： | 1.7mA |
| 電流 - 輸出 / 通道： | 125mA |
| 電壓 - 電源，單路/雙路(±)： | 3 V ~ 12 V，±1.5 V ~ 6 V |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 8-TSSOP，8-MSOP（0.118"，3.00mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 8-MSOP |
| 包裝： | 管件 |
REV. B
–14–
AD8012
Choosing the Appropriate Turns Ratio for the Transformer
Increasing the peak-to-peak output signal of the amplifier in the
previous example and adding a variation in the turns ratio of the
transformer can yield further enhancements to the circuit. The
output signal swing of the AD8012 can be increased to about
±3.9 V before clipping occurs. This increases the peak-to-peak
output of the differential amplifier to 15.6 V. Because the signal
applied to the primary winding is now bigger, the transformer
turns ratio of 1:1 can be replaced with a (step-down) turns ratio
of about 1.3:1 (from amplifier to line). This steps the 7.8 V
peak-to-peak primary voltage down to 6 V. This is the same
secondary voltage of the earlier examples, so the resulting power
delivered to the line is the same.
The received signal, which is small relative to the transmitted
signal, will, however, be stepped up by a factor of 1.3. Amplifying
the received signal in this manner enhances its signal-to-noise
ratio and is useful when the received signal is small compared to
the to-be-transmitted signal.
The impedance reflected from the 135
line now becomes
228
(1.32
135
). With a correctly terminated line, the
amplifier must now drive a total load of 456
(114 + 114
+ 228
), considerably more than the original 270 load. This
reduces the drive current from the op amps by about 40%.
More significant, however, is the reduction in dynamic power
consumption—that is, the power the amplifier must consume in
order to deliver the load power. Increasing the output signal so
that it is as close as possible to the power rails minimizes the
power consumed in the amplifier.
There is, however, a price to pay in terms of increased signal
distortion. Increasing the output signal of each op amp from the
original
± 3 V to ± 3.9 V reduces the spurious-free dynamic
range (SFDR) from –65 dB to –50 dB (measured at 500 kHz),
even though the overall load impedance has increased from
270
to 456 .
LAYOUT CONSIDERATIONS
The specified high speed performance of the AD8012 requires
careful attention to board layout and component selection.
Table I shows recommended component values for the AD8012
and Figures 8–13 show recommended layouts for the 8-lead
SOIC and MSOP packages for a positive gain. Proper RF
design techniques and low parasitic component selections
are mandatory.
The PCB should have a ground plane covering all unused
portions of the component side of the board to provide a low
impedance ground path. The ground plane should be removed
from the area near the input pins to reduce stray capacitance.
Chip capacitors should be used for supply bypassing (see Figure 7).
One end should be connected to the ground plane and the other
within 1/8 inch of each power pin. An additional (4.7
F to 10 F)
tantalum electrolytic capacitor should be connected in parallel.
The feedback resistor should be located close to the inverting
input pin in order to keep the stray capacitance at this node to
a minimum. Capacitance greater than 1.5 pF at the inverting
input will significantly affect high speed performance when
operating at low noninverting gains.
Stripline design techniques should be used for long signal traces
(greater than about 1 inch). They should be designed with the
proper system characteristic impedance and be properly termi-
nated at each end.
0.1 F
INVERTING CONFIGURATION
VOUT
RF
10 F
NONINVERTING CONFIGURATION
VOUT
RG
RF
RT
0.1 F
10 F
RT
VIN
RG
VIN
*RO CHOSEN FOR CHARACTERISTIC IMPEDANCE.
+VS
+
–VS
RO*
*RO CHOSEN FOR CHARACTERISTIC IMPEDANCE.
Figure 7. Inverting and Noninverting Configurations
Table I. Typical Bandwidth vs. Gain Setting Resistors
Small Signal –3 dB BW (MHz),
Gain
RF
RG
RT
VS =
5 V, RL = 1 k
–1
750
750
53.6
110
+1
750
49.9
350
+2
750
750
49.9
150
+10
750
82.5
49.9
40
RT chosen for 50
characteristic input impedance.
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| AD8012ARM-EBZ | 功能描述:BOARD EVAL FOR AD8012ARM RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - 運(yùn)算放大器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- |
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| AD8012ARM-REEL7 | 制造商:Analog Devices 功能描述:ADSL Driver Dual 8-Pin MSOP T/R 制造商:Rochester Electronics LLC 功能描述:MINI-SO DUAL 300MHZ, 1MA AMPLIFIER - Tape and Reel |
| AD8012ARMZ | 功能描述:IC OPAMP CF DUAL LP 125MA 8MSOP RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 放大器類型:通用 電路數(shù):4 輸出類型:- 轉(zhuǎn)換速率:0.6 V/µs 增益帶寬積:1MHz -3db帶寬:- 電流 - 輸入偏壓:45nA 電壓 - 輸入偏移:2000µV 電流 - 電源:1.4mA 電流 - 輸出 / 通道:40mA 電壓 - 電源，單路/雙路(±):3 V ~ 32 V，±1.5 V ~ 16 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:14-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:14-TSSOP 包裝:帶卷 (TR) 其它名稱:LM324ADTBR2G-NDLM324ADTBR2GOSTR |
| AD8012ARMZ | 制造商:Analog Devices 功能描述:IC OP AMP 350MHZ 2250V/US 8MSOP |
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