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參數(shù)資料
| 型號(hào)： | OP279 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Rail-to-Rail High Output Current Operational Amplifier(滿幅度高輸出電流運(yùn)放) |
| 中文描述： | 軌到軌高輸出電流運(yùn)算放大器（滿幅度高輸出電流運(yùn)放） |
| 文件頁(yè)數(shù)： | 12/16頁(yè) |
| 文件大?。?/td> | 327K |
| 代理商： | OP279 |
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OP279
–12–
REV. D
High Pass Configurations
In Figure 36 is an HP MFB 2-pole filter using an OP279 sec-
tion. For this filter, the gain in the passband is user configur-
able, and the signal phase is inverting. T he circuit uses one
more tuning component than the SK types. For simplicity,
capacitors C1 and C3
are set to equal standard values, and
resistors R1-R2
are selected as per the relationships noted. Gain
of this filter, H, is set by capacitors C1 and C2, and this factor
limits both gain selectability and precision. Also, input capaci-
tance C1 makes the load seen by the driving stage highly reac-
tive, and limits overall practicality of this filter. T he dire effect
of C1 loading can be tempered somewhat by using a small series
input resistance of about 100
, but can still be an issue.
7
6
5
0.1
m
F
Z
b
GIVEN:
ALPHA, F AND H (PASSBAND GAIN)
ALPHA = 1/Q
PICK A STD C1 VALUE, THEN:
C3 = C1, C2 = C1/H
R1 = ALPHA / ((2*PI*F*C1)*(2+(1/H)))
R2 = (H*(2+(1/H))) / (ALPHA*(2*PI*F*C1))
1kHz BW EXAMPLE SHOWN
(NOTE: SEE TEXT ON C1 LOADING
CONSIDERATIONS)
IN
R1
7.5k
V
OUT
U1B
OP279
R2
33.6k
V
C3
0.01
m
F
C2
0.01
m
F
C1
0.01
m
F
R = R2
Figure 36. Two-Pole, High Pass Multiple Feedback Filters
In this example, the filter gain is set to unity, the corner fre-
quency is 1 kHz, and the response is a Butterworth type. For
applications where dc output offset is critical, bias current com-
pensation can be used for the amplifier. T his is provided by
network Z
b
, where R is equal to R2, and the capacitor provides
a noise bypass.
Low Pass Configurations
Figure 37 is a LP MFB 2-pole filter using an OP279 section.
For this filter, the gain in the pass band is user configurable
over a wide range, and the pass band signal phase is inverting.
Given the design parameters for
α
, F, and H, a simplified design
process is begun by picking a standard value for C2. T hen C1
and resistors R1-R3
are selected as per the relationships noted.
Optional dc bias current compensation is provided by Z
b
, where
R is equal to the value of R3 plus the parallel equivalent value of
R1
and R2.
7
5
6
(R1
R2)+R3
GIVEN:
ALPHA, F AND H (PASSBAND GAIN)
ALPHA = 1/Q
PICK A STD C2 VALUE, THEN:
C1 = C2 (4 (H +1))/ALPHA^2
R1 = ALPHA/(4 H PI F C2)
R2 = H R1
R3 = ALPHA/(4 (H + 1) PI F C2)
1kHz BW EXAMPLE SHOWN
(NOTE: SEE TEXT ON C1 LOADING
CONSIDERATIONS)
IN
OUT
U1B
OP279
R1
11.3k
V
R2
11.3k
V
R3
5.62k
V
C2
0.01
m
F
0.1
m
F
Z
b
C1
0.04
m
F
Figure 37. Two-Pole, Low Pass Multiple Feedback Filters
Low Pass Configurations
In the LP SK arrangement of Figure 35b, R and C elements are
interchanged, and the resistors are made equal. Here the C2/C1
ratio “M” is used to set the filter
α
, as noted. T his design is begun
with the choice of a standard capacitor value for C1 and a calcu-
lation of M, which forces a value of “M
×
C1” for C2. T hen, the
value “R” for R1 and R2 is calculated as per the expression.
For highest performance, the passive components used for tun-
ing active filters deserve attention. Resistors should be 1%, low
T C, metal film types of the RN55 or RN60 style, or similar.
Capacitors should be 1% or 2% film types preferably, such as
polypropylene or polystyrene, or NPO (COG) ceramic for
smaller values. Somewhat lesser performance is available with
the use polyester capacitors.
Parasitic E ffects in Sallen-K ey Implementations
In designing these circuits, moderately low (10 k
or less) val-
ues for R1-R2 can be used to minimize the effects of Johnson
noise when critical, with of course practical tradeoffs of capaci-
tor size and expense. DC errors will result for larger values of
resistance, unless bias current compensation is used. T o add
bias compensation in the HP filter of Figure 35a, a feedback
compensation resistor with a value equal to R2 is used, shown
optionally as Z
f
. T his will minimize bias induced offset, reduc-
ing it to the product of the OP279’s I
OS
and R2. Similar com-
pensation is applied to the LP filter, using a Z
f
resistance of
R1 + R2. Using dc compensation and relatively low filter val-
ues, filter output dc errors using the OP279 will be dominated
by V
OS
, which is limited to 4 mV or less. A caveat here is
that the additional resistors increase noise substantially—for
example, an unbypassed 10 k
resistor generates
≈
12 nV/
√
Hz
of noise. However, the resistance can be ac-bypassed to elimi-
nate noise with a simple shunt capacitor, such as 0.1
μ
F.
Sallen-K ey Implementations in Single-Supply Applications
T he hookups shown illustrate a classical dual supply op amp
application, which for the OP279 would use supplies up to
±
5 V. However, these filters can also use the op amp in a
single-supply mode, with little if any alteration to the filter itself.
T o operate single-supply, the OP279 is powered from +5 V at
Pin 8 with Pin 4 grounded. T he input dc bias for the op amp
must be supplied from a dc source equal to 1/2 supply, or 2.5 V
in this case.
For the HP section, dc bias is applied to the common end of R2.
R2 is simply returned to an ac ground that is a well-bypassed
2:1 divider across the 5 V source. T his can be as simple as a
pair of 100 k
resistors with a 10
μ
F bypass cap. T he output
from the stage is then ac coupled, using an appropriate coupling
cap from U1A to the next stage. For the LP section dc bias is
applied to the input end of R1, in common with the input sig-
nal. T his dc can be taken from an unbypassed dual 100 k
divider across the supply, with the input signal ac coupled to the
divider and R1.
Multiple Feedback Filters
MFB filters, like their SK relatives, can be used as building
blocks as well. T hey feature LP and HP operation as well, but
can also be used in a bandpass BP mode. T hey have the prop-
erty of inverting operation in the pass band, since they are based
on an inverting amplifier structure. Another useful asset is their
ability to be easily configured for gain.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OP2790006SR | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| OP279GP | 制造商:Analog Devices 功能描述:OP AMP DUAL HIGH O/P RRI/O 279 制造商:Analog Devices Inc. 功能描述:Rail-to-Rail High Output Current Operational Amplifiers |
| OP279GRU | 制造商:AD 制造商全稱:Analog Devices 功能描述:Rail-to-Rail High Output Current Operational Amplifiers |
| OP279GRU-REEL | 制造商:Analog Devices 功能描述:OP Amp Dual GP R-R I/O 制造商:Rochester Electronics LLC 功能描述:RAIL-RAIL HI OUTPUT OPAMP - Tape and Reel |
| OP279GRUZ-REEL | 功能描述:IC OPAMP GP R-R 5MHZ DUAL 8TSSOP RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 產(chǎn)品培訓(xùn)模塊:Differential Circuit Design Techniques for Communication Applications 標(biāo)準(zhǔn)包裝:1 系列:- 放大器類型:RF/IF 差分 電路數(shù):1 輸出類型:差分 轉(zhuǎn)換速率:9800 V/µs 增益帶寬積:- -3db帶寬:2.9GHz 電流 - 輸入偏壓:3µA 電壓 - 輸入偏移:- 電流 - 電源:40mA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):3 V ~ 3.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-VQFN 裸露焊盤，CSP 供應(yīng)商設(shè)備封裝:16-LFCSP-VQ 包裝:剪切帶 (CT) 產(chǎn)品目錄頁(yè)面:551 (CN2011-ZH PDF) 其它名稱:ADL5561ACPZ-R7CT |
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