參數(shù)資料
型號(hào)： OPA699IDR
元件分類： 運(yùn)動(dòng)控制電子
英文描述： Wideband, High Gain VOLTAGE LIMITING AMPLIFIER
中文描述： 寬帶，高增益電壓限幅放大器
文件頁(yè)數(shù)： 16/25頁(yè)
文件大小： 461K
代理商： OPA699IDR
OPA699
SBOS261B
16
www.ti.com
WIDEBAND INVERTING OPERATION
Operating the OPA699 as an inverting amplifier has several
benefits and is particularly useful when a matched 50
source and input impedance are required. Figure 3 shows
the inverting gain of
–
4V/V circuit used as the basis of the
inverting mode typical characteristics.
LOW-GAIN COMPENSATION FOR IMPROVED SFDR
Where a low gain is desired, and inverting operation is
acceptable, a new external compensation technique can be
used to retain the full slew rate and noise benefits of the
OPA699, while giving increased loop gain and the associ-
ated distortion improvements offered by a non-unity-gain
stable op amp. This technique shapes the loop gain for good
stability, while giving an easily controlled 2nd-order low-pass
frequency response. To set the compensation capacitors (C
S
and C
F
), consider the half-circuit of Figure 5, where the 50
source is used.
Considering only the noise gain for the circuit of Figure 5, the
low-frequency noise gain (N
G1
) is set by the resistor ratio,
while the high-frequency noise gain (N
G2
) is set by the
capacitor ratio. The capacitor values set both the transition
frequencies and the high-frequency noise gain. If the high-
frequency noise gain, determined by N
G2
= 1 + C
S
/C
F
, is set
to a value greater than the recommended minimum stable
gain for the op amp, and the noise gain pole (set by 1/R
F
C
F
)
is placed correctly, a very well controlled 2nd-order low-pass
frequency response results.
In the inverting case, only the feedback resistor appears as
part of the total output load in parallel with the actual load. For
a 500
load used in the typical characteristics, this gives a
total load of 329
in this inverting configuration. The gain
resistor is set to get the desired gain (in this case, 187
for
a gain of
–
4) while an additional input resistor (R
M
) can be
used to set the total input impedance equal to the source, if
desired. In this case, R
M
= 68.1
in parallel with the 187
gain setting resistor gives a matched input impedance of
50
. This matching is only needed when the input needs to
be matched to a source impedance, as in the characteriza-
tion testing done using the circuit of Figure 3.
For bias current-cancellation matching, the noninverting input
requires a 169
resistor to ground. The calculation for this
resistor includes a DC-coupled 50
source impedance along
with R
G
and R
M
. Although this resistor will provide cancella-
tion for the bias current, it must be well-decoupled (0.1
μ
F in
Figure 3) to filter the noise contribution of the resistor and the
input current noise.
As the required R
G
resistor approaches 50
at higher gains,
the bandwidth for the circuit in Figure 3 will far exceed the
bandwidth at that same gain magnitude for the noninverting
circuit of Figure 1. This occurs due to the lower noise gain for
the circuit of Figure 3 when the 50
source impedance is
included in the analysis. For instance, at a signal gain of
–
15
(R
G
= 50
, R
M
= open, R
F
= 750
) the noise gain for the
circuit of Figure 3 will be 1 + 750
/(50
+ 50
) = 8.5 due to
the addition of the 50
source in the noise gain equation.
This approach gives considerably higher bandwidth than the
noninverting gain of +15. Using the 1GHz gain bandwidth
product for the OPA699, an inverting gain of
–
15 from a 50
source to a 50
R
G
will give 140MHz bandwidth, whereas
the noninverting gain of +8 will give 55MHz, as shown in the
measured results of Figure 4.
OPA699
–
5V
V
I
–
2V
+5V
+2V
R
68.1
R
F
750
R
G
187
500
0.1
μ
F
R
T
169
V
H
V
L
V
O
50
Source
1M
10M
100M
1G
Frequency (Hz)
G
24
21
18
15
12
9
G = +15
G =
–
15
R
F
402
C
13pF
OPA699
+5V
–
5V
V
O
V
I
C
2.8pF
200
R
G
402
V
H
V
L
FIGURE 3. Inverting G =
–
4 Specifications and Test Circuit.
FIGURE 4. G = +15 and
–
15 Frequency Response.
FIGURE 5. Broadband, Low-Inverting Gain External
Compensation.
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參數(shù)描述
OPA699IDRG4 功能描述:高速運(yùn)算放大器 Wideband High Gain Vltg Limiting 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
OPA699M 制造商:TI 制造商全稱:Texas Instruments 功能描述:GAIN 4 STABLE WIDEBAND VOLTAGE LIMITING AMPLIFIER
OPA699MJD 制造商:Texas Instruments 功能描述:OP Amp Single Volt Fdbk ±6V/12V 8-Pin SBCDIP Tube
OPA703 制造商:TI 制造商全稱:Texas Instruments 功能描述:CMOS, Rail-to-Rail, I/O OPERATIONAL AMPLIFIERS
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