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參數(shù)資料
| 型號： | OPA683IDR |
| 元件分類： | 運動控制電子 |
| 英文描述： | OP-AMP|SINGLE|BIPOLAR|SOP|8PIN|PLASTIC |
| 中文描述： | 運放|單|雙極|專科| 8引腳|塑料 |
| 文件頁數(shù)： | 14/24頁 |
| 文件大?。?/td> | 400K |
| 代理商： | OPA683IDR |
OPA683
SBOS221B
14
www.ti.com
VERY LOW POWER ACTIVE FILTER
The OPA683 provides an exceptionally capable gain block
for implementing Sallen-Key type filters. Typically, the band-
width interaction with gain setting for low power amplifiers,
constrain these filters to using unity-gain amplifiers. Since
the OPA683 CFB
plus
design holds very high bandwidth to
high gains, implementations that provide signal gain, as well
as the desired filter shape, are easily implemented. Figure 6
shows an example of a 5MHz 2nd-order low-pass filter where
the amplifier is providing a voltage gain of 4. This single-
supply implementation (applicable to single +12V operation
as well) consumes only 5.1mW quiescent power. The two
12.5k
resistors bias the input and output at the supply
midpoint while the three 0.1
μ
F capacitors block off the DC
current paths to ground for this mid-scale operating point.
The filter resistors and capacitors have been adjusted
to provide a Butterworth (Q = 0.707) response with a
Wo = 2
π
5MHz. This gives a flat passband response with
a
–
3dB cutoff at 5MHz. Figure 7 shows the small-signal
frequency response for the circuit of Figure 6.
HIGH GAIN HF AMPLIFIER
Where high gains at moderate frequencies are required in an
HF receiver channel, the OPA683 can provide a very low
power solution with moderate input noise figure. Figure 8
shows a technique that can improve the noise figure with no
added power. An input transformer provides a noiseless
voltage gain at the cost of higher source impedance for the
amplifier
’
s noninverting input current noise. The circuit of
Figure 8, using a 1:4 turns ratio (1:16 impedance ratio)
transformer, reduces the input noise figure from about 20dB
for just the amplifier to 10.6dB in combination. The bandwidth
for this circuit will be principally set by the transformer since
the OPA683 will give > 80MHz for the gain of 20V/V shown
in Figure 8. The overall circuit gives a gain to a matched 50
load of 32dB (40V/V) from the transformer input. This ex-
ample circuit provides this gain using only 10mW of quies-
cent power with application from 500kHz to 30MHz.
1.4k
OPA683
+5V
12.5k
12.5k
467
0.1
μ
F
V
I
0.1
μ
F
446
157
100pF
Supply
De-coupling
Not Shown
V
O
1k
150pF
0.1
μ
F
15
12
9
6
3
0
–
3
–
6
–
9
Frequency (Hz)
10
3
20E6
10
5
10
4
10
6
10
7
LOW POWER 5MHz LP ACTIVE FILTER
G
FIGURE 6. 5MHz, 2nd-Order Low Pass Filter.
FIGURE 7. Low Power Active Filter Frequency Response.
OPA683
+5V
–
5V
50
50
63
0.01
μ
F
800
P
I
P
O
P
O
= 32dB
P
I
1.2k
50
10.6dB
Noise Figure
1:4
FIGURE 8. Low Power, High Gain HF Amplifier.
LOW POWER, ADC DRIVER
Where a low power, single-supply interface to a single-ended
input +5V ADC is required, the circuit of Figure 9 can provide
a very flexible, high performance solution. Running in an AC-
coupled inverting mode allows the noninverting input to be
used for the common-mode voltage from the ADS820 con-
verter. This midpoint reference biases both the noninverting
converter input and the amplifier noninverting input. With an
AC-coupled gain path, this +2.5V DC bias has a gain of +1
to the output putting the output at the DC midpoint for the
converter. The output then drives through an isolating resis-
tor (60
) to the inverting input of the converter which is
further decoupled by a 22pF external capacitance to add to
its 5pF input capacitance. This coupling network provides a
high cutoff low-pass while also giving a low source imped-
ance at high frequencies for the converter. The gain for this
circuit is set by adjusting R
G
to the desired value. For a 2Vp-p
maximum output driving the light load of Figure 9, the
OPA683 will provide <
–
80dBc THD through 1MHz as shown
in the Typical Characteristics. One of the important advan-
tages for this CFB
plus
amplifier is that this distortion does not
degrade significantly at higher gains.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OPA683IDRG4 | 功能描述:高速運算放大器 Very Lo-Pwr Current Feedback RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)償電壓:0.5 mV 轉(zhuǎn)換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| OPA684 | 制造商:BB 制造商全稱:BB 功能描述:Quad, Low-Power, Current-Feedback OPERATIONAL AMPLIFIER |
| OPA684ID | 功能描述:高速運算放大器 Low-Power Current Feedback RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)償電壓:0.5 mV 轉(zhuǎn)換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| OPA684IDBVR | 功能描述:高速運算放大器 Low-Power Current Feedback RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)償電壓:0.5 mV 轉(zhuǎn)換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| OPA684IDBVRG4 | 功能描述:高速運算放大器 Low-Power Current Feedback RoHS:否 制造商:Texas Instruments 通道數(shù)量:1 電壓增益 dB:116 dB 輸入補(bǔ)償電壓:0.5 mV 轉(zhuǎn)換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
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