LINER LTC1566-1

Final Electrical Specifications
LT1567
1.4nV/√Hz 175MHz Op Amp
and Inverter / Filter Building Block
August 2001
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DESCRIPTIO
FEATURES
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Single-Ended to Differential Conversion
Low Noise: 1.4nV/√Hz
20µVRMS Total Wideband Noise Filter with 2MHz fC
Dynamic Range: 104dB SNR at ±5V
Supply Voltage 2.7V to 12V Total
Rail-to-Rail Outputs
DC Accurate: Op Amp VOS 1mV (Typ)
Trimmed Bandwidth for Accurate Filters
MSOP-8 Surface-Mount Package
No External Clock Required
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APPLICATIO S
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Low Noise, High Speed Filters to 5MHz
Cellular Base Stations
Communication Channel or Roofing Filters
Antialias or Reconstruction Filtering
Video Signal Processing
Single-Ended to Differential Conversion
In addition to low noise and high speed LT1567 features
single-ended to differential conversion for direct driving of
high speed A/D converters. The LT1567 operates from a
total power-supply voltage of 2.7V to 12V and can support
signal-to-noise ratios above 100dB.
The LT1567 is available in an 8-lead MSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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The LT®1567 is an analog building block optimized for
very low-noise high-frequency filter applications. It contains two wideband operational amplifiers, one of them
internally configured as a unity-gain inverter. With the
addition of two capacitors, the LT1567 becomes a flexible
second-order filter section with cutoff frequency (fC) up to
5MHz, ideal for antialiasing or for channel filtering in highspeed data communications systems.
TYPICAL APPLICATIO
2MHz 3-Pole Antialias Filter with
Single-Ended to Differential Conversion
Frequency Response
V+
0.1µF
536Ω
6
0
270pF
536Ω
VIN
1
8
2
7
147Ω
270pF
0.1µF
3
4
LT1567
6
5
+AIN
ADC
270pF
–AIN
147Ω
GAIN (dB)
536Ω
12
–6
–12
–18
–24
LTC1420
–30
0.1µF
V–
NOTE: THIS IS RESPONSE FROM
SINGLE-ENDED VIN TO DIFFERENTIAL
VOLTAGE ACROSS ADC INPUT,
SO THERE IS A BUILT-IN 6dB GAIN.
–36
100
96dB DIFFERENTIAL SNR AT 3V TOTAL SUPPLY.
1567 TA01
1M
FREQUENCY (Hz)
10M
1567 TA01a
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LT1567
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ABSOLUTE
AXI U RATI GS
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PACKAGE/ORDER I FOR ATIO
(Note 1)
Total Supply Voltage (V+ to V –) ............................ 12.6V
Input Voltage (Note 2) ............................................. ±VS
Input Current (Note 2) .......................................... ±5mA
Operating Temperature Range ..................... 0°C to 70°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
TOP VIEW
OAOUT
OAIN
BYPASS
V–
1
2
3
4
8
7
6
5
LT1567CMS8
V+
INVOUT
INVIN
GND
MS8 PART
MARKING
MS8 PACKAGE
8-LEAD PLASTIC MSOP
TJMAX = 40°C, θJA = 160°C/W
LTWH
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications that apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = ±2.5V, RL = 1K, VOUT = 0 both amplifiers unless otherwise noted.
PARAMETER
CONDITIONS
MIN
Total Supply Voltage
TYP
2.7
MAX
UNITS
12
V
15
16
19
mA
mA
mA
Supply Current
VS = ±1.5V
VS = ±2.5V
VS = ±5V
●
●
●
OA Output Positive Voltage Swing
VS = ±1.5V, RL = 1k
VS = ±2.5V, RL = 1k
VS = ±2.5V, RL=100
VS = ±5V, RL = 1k
●
●
●
●
1.30
2.20
2.00
4.70
1.45
2.40
2.25
4.85
V
V
V
V
OA Output Negative Voltage Swing
VS = ±1.5V, RL = 1k
VS = ±2.5V, RL = 1k
VS = ±2.5V, RL=100
VS = ±5V, RL = 1k
●
●
●
●
–1.30
–2.20
–2.00
–4.70
–1.45
–2.44
–2.20
–4.90
V
V
V
V
INV Output Positive Voltage Swing
VS = ±1.5V, RL = 1k
VS = ±2.5V, RL = 1k
VS = ±5V, RL = 1k
●
●
●
1.30
2.20
4.60
1.40
2.40
4.90
V
V
V
INV Output Negative Voltage Swing
VS = ±1.5V, RL = 1k
VS = ±2.5V, RL = 1k
VS = ±5V, RL = 1k
●
●
●
–1.30
–2.20
–4.50
–1.40
–2.40
–4.80
V
V
V
Common Mode (GND) Input Voltage Range
(See Pin Functions)
VS = ±1.5V
VS = ±5V
●
●
–0.25
–2.5
DC Common Mode Rejection Ratio (CMRR)
VS = ±1.5V, VCM = –0.25V to 0.25V
VS = ±5V, VCM = –2.5V to 2.5V
●
●
90
75
90
dB
dB
VS = ±1.5V to ±5V, VCM = 0V
●
80
100
dB
DC Power-Supply Rejection Ratio (PSRR)
8.5
9
11
0.25
2.5
V
V
OA Input Offset Voltage Magnitude
●
1
3
mV
INV Output Offset Voltage Magnitude
●
6
9
mV
2
LT1567
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications that apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = ±2.5V, RL = 1K, VOUT = 0 both amplifiers unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
OA Input Bias Current
●
3
10
µA
GND Input Bias Current
●
6
15
µA
OA DC Open-Loop Gain
VS = ±1.5V, RL = 1k, VO = –1V to 1V
VS = ±2.5V, RL = 1k, VO= –2V to 2V
VS = ±2.5V, RL = 100, VO = –1.5V to 1.5V
VS = ±5V, RL = 1k, VO = –4V to 4V
●
●
●
●
7.5
10
1.2
15
INV DC Gain Magnitude
VS = ±1.5V, RL = 1k, VIN = –1V to 1V
VS = ±2.5V, RL = 1k, VIN = –2V to 2V
VS = ±2.5V, RL = 100, VIN = –1.5V to 1.5V
VS = ±5V, RL = 1k, VIN = –4V to 4V
●
●
●
●
0.97
0.97
0.97
0.97
INV DC Input Resistance
VS = ±2.5V, RL = 1k, VIN = –2V to 2V
●
450
600
OA Gain-Bandwidth Product
Measured at 2MHz, VS = ±1.5V
Measured at 2MHz, VS = ±2.5V
Measured at 2MHz, VS = ±5V
●
●
●
100
110
120
160
175
190
INV AC Gain Magnitude
Measured at 2MHz
●
0.96
1.0
OA Slew Rate Magnitude
23
35
4.0
40
V/mV
V/mV
V/mV
V/mV
1.04
1.04
1.04
1.04
750
V/V
V/V
V/V
V/V
Ω
MHz
MHz
MHz
1.05
V/V
49
V/µsec
f = 100kHz
1.4
nV/√Hz
OA Input Current Noise Density
f = 100kHz
1.0
pA/√Hz
Wideband Output Noise for a Second-Order Filter (Figure 1)
fC = 2MHz, BW = 4MHz
fC = 5MHz, BW = 10MHz
20
30
µVRMS
µVRMS
Total Harmonic Distortion (THD)
for a Second-Order Filter (Figure 1)
f = 1MHz, fC = 2MHz, VOUT = 1VRMS
f = 2.5MHz, fC = 5MHz, VOUT = 1VRMS
–88
–70
dB
dB
35
mA
0.1
Ω
OA Input Voltage Noise Density
Output Short-Circuit Current (Either Output)
Output Impedance
f = 100kHz, OA Connected as
Unity-Gain Inverter
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The inputs of each op amp are protected by back-to-back diodes.
If either differential input voltage exceeds 1.4V, the input current should be
limited to less than 5mA.
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LT1567
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PI FU CTIO S
OAOUT (Pin 1): Output of the Uncommitted Op Amp (OA).
As with most wideband op amps, it is important to avoid
connecting heavy capacitive loads (above about 10pF)
directly to this output. Such loads, exhibiting low impedance (circa 100Ω) at the op amp’s unity-gain crossover
frequency (circa 100MHz), will impair AC stability.
GND (Pin 5): DC Ground Input. Sets the noninverting
inputs for the two internal amplifiers; designed for use as
a DC reference, not a signal input.The GND input includes
a small series resistor, both to balance DC offsets in the
presence of input bias currents and also to suppress the
“Q” factor of possible parasitic high-frequency resonant
circuits introduced by wiring inductance. The on-chip
ground reference at the noninverting inputs of the two
amplifiers is decoupled for very high frequencies with a
small internal capacitor to the chip substrate, nominally
7pF. An external capacitor, typically 0.1µF, to a nearby
ground plane should be added at the BYPASS pin for a
clean wideband ground reference.
OAIN (Pin 2): Inverting or “–” Input of the Uncommitted
Op Amp (OA) in the LT1567. The noninverting or “+” input
of this amplifier is shared with that of the INV amplifier and
accessed via the GND and BYPASS pins. The OA amplifier
is optimized for minimal wideband noise.
BYPASS (Pin 3): AC Ground Bypass. Designed for a
decoupling capacitor, typically 0.1µF, to a printed circuit
ground plane using the shortest possible wiring. Use GND
for DC connection of the amplifier noninverting inputs as
described in the GND (Pin 5) description.
INVIN (Pin 6): Unity-Gain Inverter Input. The “inverter”
(INV) amplifier in the LT1567 is connected to internal
resistors (nominally 600Ω each) to form a closed-loop
amplifier with a wideband voltage gain of nominally –1.
The amplifier in this position is similar to the uncommitted
op amp (OA) but is optimized for high frequency linearity.
Power Supply Pins (Pins 4, 8): The V – and V+ pins should
be bypassed with 0.1µF capacitors to an adequate analog
ground plane using the shortest possible wiring. Electrically clean supplies and a low impedance ground are
important for the high dynamic range and bandwidth
available from the LT1567. Low noise linear power supplies are recommended. Switching supplies are not recommended because of the inevitable risk of their switching noise coupling into the signal path, reducing dynamic
range.
INVOUT (Pin 7): Output of the INV or “Inverter” Amplifier,
with a Nominal Gain of –1 from the INVIN Pin. As with
most wideband op amps, it is important to avoid connecting heavy capacitive loads (above about 10pF) directly to
this output. Such loads, exhibiting low impedance (circa
100 ohms) at the op amp’s unity-gain crossover frequency
(circa 100MHz), will impair AC stability.
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BLOCK DIAGRA
Block Diagram with Top View of Pins
OAIN
2
BYPASS
3
–
1
+
OAOUT
8
V+
7
INVOUT
6
INVIN
5
GND
+
–
600Ω
7pF
V–
4
4
600Ω
150Ω
LT1567
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APPLICATIO S I FOR ATIO
Functional Description
Dealing with High Source Impedances
The LT1567 contains two low-noise wideband operational
amplifiers, one of them connected internally as a unitygain inverter. These two amplifiers can form a secondorder multiple-feedback filter configuration (Figure 1) for
megahertz signal frequencies, with exceptionally low total
noise. The amplifier in the dedicated inverter (INV) is
optimized for better high frequency linearity while the
uncommitted operational amplifier (OA) is optimized for
lower input noise voltage, according to the different
sensitivities to these effects in the filter section. This
combination produces a low-noise filter with better distortion performance than would be possible with identical
amplifiers.
The voltage VIN in Figure 1 , on the left side of R1, is the
signal voltage that the filter sees. If a voltage source with
significant internal impedance drives the VIN node in
Figure 1, then the filter input VIN may differ from the
source’s open-circuit output, and the difference can be
complex, because the filter presents a complex impedance to VIN. A rule of thumb is that a source impedance is
negligibly “low” if it is much smaller than R1 at frequencies
of interest. Otherwise, the source impedance (resistive or
reactive) effectively adds to R1 and may change the signal
frequency response compared to that with a low source
impedance. If the source is resistive and predictable, then
it may be possible to design for it by reducing R1.
Unpredictable or nonresistive source impedances that are
not well below R1 should be buffered.
Signal Ground
Both operational amplifiers within the LT1567 are designed for inverting operation (constant common mode
input) and they share a single ground reference node on
the chip. Two pins permit access to this node: GND and
BYPASS. For a clean on-chip ground reference over a wide
bandwidth, the normal procedure is to connect GND to a
DC ground potential and BYPASS to a decoupling capacitor that returns to a ground plane.
Differential Output Feature
The multiple-feedback filter section of Figure 1 inherently
includes two outputs of opposite signal polarity: a DCinverting output from the OA (Pin 1) and a DC noninverting
output from the INV block (Pin 7). These two outputs
maintain equal gain and 180º phase shift over a wide
frequency range. This feature permits choosing the signal
polarity in single-ended applications, and also performs
single-ended-to-differential conversion. The latter property is useful in an antialias filter to drive standard monolithic A/D converters having differential inputs, as illustrated on page 1.
Construction and Instrumentation Cautions
Electrically clean construction is important in applications
seeking the full dynamic range and bandwidth of the
LT1567. Using the shortest possible wiring or printedcircuit paths will minimize parasitic capacitance and inductance. High quality supply bypass capacitors of 0.1µF
near the chip, connected to a ground plane, provide good
decoupling from a clean, low inductance power source.
But several inches of wire (i.e., a few microhenrys of
inductance) from the power supplies, unless decoupled
by substantial capacitance (≥10µF) near the chip, can
cause a high Q LC resonance in the hundreds of kHz in the
chip’s supplies or ground reference. This may impair filter
performance at those frequencies. In stringent filter applications we have often found that a compact, carefully laid
out printed circuit board with good ground plane makes a
difference in both stopband rejection and distortion.
Finally, equipment to measure filter performance can itself
introduce distortion or noise floors. Checking for these
limits with a wire replacing the filter is a prudent routine
procedure.
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LT1567
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APPLICATIO S I FOR ATIO
R2
VIN
R1
C1
R3
VOUT
(INVERTING)
–
VOUT2
(NONINVERTING)
(OPTIONAL)
–1
C2
VS/2
+
LT1567
1567 F01
RESPONSE
0.1dB CHEBYSHEV, 1MHz
0.1dB CHEBYSHEV, 2MHz
0.1dB CHEBYSHEV, 5MHz
BUTTERWORTH, 2MHZ
C1
120pF
120pF
120pF
180pF
C2
180pF
180pF
180pF
180pF
R1, R2
1050Ω
523Ω
205Ω
604Ω
R3
1180Ω
590Ω
232Ω
309Ω
Figure 1. Basic 2nd-Order Lowpass Section Using One LT1567
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TYPICAL APPLICATIO
2nd Order Bandpass Filter
fCENTER = 1MHz, –3dB BW = 0.707MHZ
C2
470pF
R3
475Ω
C1
470pF
R1
475Ω
–
VIN
–1
VS/2
R2
475Ω
VOUT
+
LT1567
1567 TA02
fCENTER
IF R2 = R3 = R AND C1 = C2 = C, fCENTER = √(R/R1) + 1, –3dB BW =
√(R/R1) + 1
2πRC
GAIN AT fCENTER = R/R1, MAXIMUM fCENTER IS
6
5MHz
GAIN
LT1567
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PACKAGE DESCRIPTIO
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660)
0.118 ± 0.004*
(3.00 ± 0.102)
8
7 6
5
0.118 ± 0.004**
(3.00 ± 0.102)
0.193 ± 0.006
(4.90 ± 0.15)
1
2 3
4
0.043
(1.10)
MAX
0.007
(0.18)
0.034
(0.86)
REF
0° – 6° TYP
0.021 ± 0.006
(0.53 ± 0.015)
SEATING
PLANE
0.009 – 0.015
(0.22 – 0.38)
0.0256
(0.65)
BSC
0.005 ± 0.002
(0.13 ± 0.05)
MSOP (MS8) 1100
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
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LT1567
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TYPICAL APPLICATIO
Single Supply Single-Ended to Differential
First Order Lowpass Filter with Gain
VOUT+
R2
VOUT–
C1
150pF
R1
VIN
1
8
2
7
0.1µF
3
LT1567
4
V+
0.1µF
6
5
GAIN = R2/R1
f– 3dB = 1/(2π R2 C1)
f– 3dB MAX = 5MHz
2.49k
2.49k
1567 TA03
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10kHz to 150kHz Digitally Controlled Filter and 4-Bit PGA
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8
Linear Technology Corporation
COMMENTS
1567i LT/TP 0801 1.5K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2001