The OPA3684 provides a new level of performance in low-power, wideband, current-feedback (CFB) amplifiers

OPA3684

Manufacturer Part NumberOPA3684
DescriptionThe OPA3684 provides a new level of performance in low-power, wideband, current-feedback (CFB) amplifiers
ManufacturerTexas Instruments
OPA3684 datasheet
 


Specifications of OPA3684

Number Of Channels3Bw @ Acl(mhz)210
Acl, Min Stable Gain(v/v)1Slew Rate(typ)(v/us)820
Settling Time (0.1%)(typ)(ns)11Vn At Flatband(typ)(nv/rthz)3.7
Vs(min)(v)5Vs(max)(v)12
Iq Per Channel(max)(ma)3.9Io(typ)(ma)120
2nd Harmonic(dbc)803rd Harmonic(dbc)80
@ Mhz5Thd (fc=1 Mhz)(typ)(db)-79
Diff Gain(%)0.04Diff Phase(deg)0.02
Vio(max)(mv)3.5Offset Voltage Drift (+/-)(max)(uv/degrees Celsius)12
Iib(max)(na)13000Operating Temperature Range(c)-40 to 85
Pin/package14SOIC, 16SSOP/QSOP  
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Low-Power, Triple Current-Feedback
OPERATIONAL AMPLIFIER With Disable
FEATURES
MINIMAL BANDWIDTH CHANGE VERSUS GAIN
170MHz BANDWIDTH: G = +2
> 120MHz BANDWIDTH TO GAIN > +10
LOW DISTORTION: < –82dBc at 5MHz
HIGH OUTPUT CURRENT: 120mA
SINGLE +5V TO +12V SUPPLY OPERATION
DUAL 2.5V TO 6.0V SUPPLY OPERATION
LOW SUPPLY CURRENT: 1.7mA/ch
LOW SHUTDOWN CURRENT: 100 A/ch
DESCRIPTION
The OPA3684 provides a new level of performance in low-power,
wideband, current-feedback (CFB) amplifiers. This CFB
plifier among the first to use an internally closed-loop input buffer
stage that enhances performance significantly over earlier low-
power CFB amplifiers. While retaining the benefits of very low
power operation, this new architecture provides many of the
benefits of a more ideal CFB amplifier. The closed-loop input stage
buffer gives a very low and linearized impedance path at the
inverting input to sense the feedback error current. This improved
inverting input impedance retains exceptional bandwidth to much
higher gains and improves harmonic distortion over earlier solu-
tions limited by inverting input linearity. Beyond simple high-gain
applications, the OPA3684 CFB
amplifier permits the gain
PLUS
setting element to be set with considerable freedom from amplifier
bandwidth interaction. This allows frequency response peaking
elements to be added, multiple input inverting summing circuits to
1 of 3 Channels
V+
Z
V–
(S)
I
ERR
R
F
R
G
Low-Power
Patent Pending
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
APPLICATIONS
RGB LINE DRIVERS
LOW-POWER BROADCAST VIDEO DRIVERS
EQUALIZING FILTERS
MULTICHANNEL SUMMING AMPLIFIERS
PROFESSIONAL CAMERAS
ADC INPUT DRIVERS
have greater bandwidth, and low-power line drivers to meet the
demanding requirements of studio cameras and broadcast video.
The output capability of the OPA3684 also sets a new mark in
am-
PLUS
performance for low-power current-feedback amplifiers. Delivering
a full 4Vp-p swing on 5V supplies, the OPA3684 also has the
output current to support > 3Vp-p into 50 . This minimal output
headroom requirement is complemented by a similar 1.2V input
stage headroom giving exceptional capability for single +5V opera-
tion.
The OPA3684’s low 1.7mA/ch supply current is precisely trimmed
at 25 C. This trim, along with low shift over temperature and supply
voltage, gives a very robust design over a wide range of operating
conditions. System power may be further reduced by using the
optional disable control pin. Leaving this disable pin open, or holding
it HIGH, gives normal operation. If pulled LOW, the OPA3684 supply
current drops to less than 100 A/ch while the I/O pins go to a high
impedance state.
6
3
0
–3
+
V
O
–6
–9
I
–12
ERR
–15
–18
–21
R
–24
10
Amplifier
www.ti.com
OPA3684
SBOS241C – MAY 2002 – REVISED JULY 2008
BW (MHz) vs GAIN
G = 2
G = 5
G = 10
G = 20
G = 50
= 800
G = 100
F
100
MHz
Copyright © 2002-2008, Texas Instruments Incorporated
G = 1
200

OPA3684 Summary of contents

  • Page 1

    ... PROFESSIONAL CAMERAS ADC INPUT DRIVERS have greater bandwidth, and low-power line drivers to meet the demanding requirements of studio cameras and broadcast video. The output capability of the OPA3684 also sets a new mark in am- PLUS performance for low-power current-feedback amplifiers. Delivering a full 4Vp-p swing on 5V supplies, the OPA3684 also has the output current to support > ...

  • Page 2

    ... Junction Temperature (T ) ........................................................... +175 C J ESD Rating: HBM ............................................................................ 1900V CDM ........................................................................... 1500V NOTE: (1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. OPA3684 RELATED PRODUCTS SINGLES DUALS TRIPLES QUADS OPA684 OPA2684 — OPA4684 ...

  • Page 3

    ... DIS 5 1 5V/per Channel 1 5V/per Channel 1.7 S Input Referred 60 –40 to +85 Junction-to-Ambient 100 100 CMIR limits. www.ti.com OPA3684ID, IDBQ MIN/MAX OVER TEMPERATURE – MIN/ (1) (2) (2) + +85 C UNITS MAX MHz typ 120 118 117 MHz min ...

  • Page 4

    ... V = 0V/Channel 80 DIS 5 2 +5V/per Channel 1. +5V/per Channel 1.44 S Input Referred 65 –40 to +85 100 100 CMIR limits. www.ti.com OPA3684ID, IDBQ MIN/MAX OVER TEMPERATURE – MIN/ (1) (2) (2) + +85 C UNITS MAX MHz typ MHz min MHz min MHz ...

  • Page 5

    ... See Figure 1 – Frequency (MHz) NONINVERTING PULSE RESPONSE 0 0.6 0.4 Large-Signal Right Scale 0.2 Small-Signal Left Scale 0 –0.2 –0.4 –0.6 See Figure 1 –0.8 Time (10ns/div) OPA3684 SBOS241C = – – – 100 –12 100 200 1 ...

  • Page 6

    ... 100 L –60 –70 –80 –90 5 2.5 3 HARMONIC DISTORTION vs INVERTING GAIN –50 –55 –60 –65 –70 –75 –80 –85 – www.ti.com 2nd-Harmonic 3rd-Harmonic Frequency (MHz) 2nd-Harmonic 3rd-Harmonic 3.5 4 4.5 5 5.5 6 Supply Voltage ( V) 2nd-Harmonic 3rd-Harmonic 10 20 Inverting Gain (V/V) OPA3684 SBOS241C ...

  • Page 7

    ... Power at Load (each tone, dBm) DISABLED FEEDTHROUGH = 0 See Figure Frequency (MHz) SMALL-SIGNAL BANDWIDTH vs C LOAD 12pF 100pF +5V 75pF OPA3684 50pF –5V 800 33pF 20pF 10 100 Frequency (MHz 100 5pF 300 7 ...

  • Page 8

    ... OUTPUT CURRENT AND VOLTAGE LIMITATIONS Limit Each –100 – 100 I (MA) O SUPPLY AND OUTPUT CURRENT vs AMBIENT TEMPERATURE Sourcing Output Current Supply Current Sinking Output Current 100 Ambient Temperature ( C) OPA3684 SBOS241C 0 –30 –60 –90 –120 –150 –180 Power Limit 150 1.9 1.8 1.7 1.6 1.5 125 ...

  • Page 9

    ... ALL HOSTILE CROSSTALK 1Vp-p Output 2-Channels, 100 Load 1 10 Frequency (MHz) INVERTING OVERDRIVE RECOVERY Output Voltage Right Scale Input Voltage See Figure 2 Left Scale Time (100ns/div) CLOSED-LOOP OUTPUT IMPEDANCE vs FREQUENCY 1/3 OPA3684 Z 800 O 800 1k 10k 100k 1M 10M Frequency (Hz) 100 8.0 6.4 4.8 3.2 1.6 0 – ...

  • Page 10

    ... – – – – –20 10 Frequency (MHz 0.2Vp 0.5Vp 1Vp 2Vp 100 Frequency (MHz) INVERTING PULSE RESPONSE Small-Signal Left Scale Large-Signal Right Scale See Figure 4 Time (10ns/div) OPA3684 100 200 200 1.6 1.2 0.8 0.4 0 –0.4 –0.8 –1.2 –1.6 SBOS241C ...

  • Page 11

    ... See Figure 3 –90 0.5 1 Output Voltage (Vp-p) SUPPLY AND OUTPUT CURRENT vs AMBIENT TEMPERATURE 100 Right-Scale 90 Supply Current 80 Sourcing Output Current 70 Left-Scale Sinking Output Current 60 50 –50 – Ambient Temperature ( C) OPA3684 SBOS241C = +5V S –50 –60 –70 –80 –90 1k –50 –60 –70 –80 – 1.5 0.16 0.14 1.4 0.12 0.10 1.3 Left-Scale 0 ...

  • Page 12

    ... Generally, the optimum feedback resistor value (for nomi- nally flat frequency response +2) will increase in value 50 Load as the total supply voltage across the OPA3684 is reduced. See Figure 3 for the AC-coupled, single +5V supply, gain of +2V/V circuit configuration used as a basis for the +5V only Electrical and Typical Characteristics for each channel ...

  • Page 13

    ... Test Circuit. LOW-POWER, VIDEO LINE DRIVER APPLICATIONS 0 For low-power, video line driving, the OPA3684 provides the output current and linearity to support 3 channels of either 50 Load single video lines video lines in parallel on each output. Figure 5 shows a typical 5V supply video line driver application where only one channel is shown and only a single line is being driven ...

  • Page 14

    ... V Red OUT LOW-POWER, FLEXIBLE GAIN, DIFFERENTIAL 75 Line RECEIVER The 3 channels available in the OPA3684 can be applied to a very flexible differential to single-ended receiver. Since the bandwidth does not depend on the gain setting, the gain setting element of Figure Green OUT range with minimal impact on resulting bandwidth ...

  • Page 15

    ... Wideband current-feedback op amps make ideal elements for implementing high-speed active filters where the amplifier is used as a fixed gain block inside a passive RC circuit network. The triple channel OPA3684 can be used as a very effective video Digital-to-Analog Converter (DAC) recon- struction filter and line driver. Figure 9 shows an example of this where the delay-equalized filter compensates for the DAC’ ...

  • Page 16

    ... CMRR for a single op amp differential amplifier configuration. For the buffer gain CMRR = –20 • log(1 – ). The closed-loop input stage buffer used in the OPA3684 gives a buffer gain more closely approaching 1.00 and this shows slightly higher CMRR than previous current-feedback op amps. ...

  • Page 17

    ... SBOS241C inverting node voltage. While it is always important to keep the inverting node capacitance low for any current-feedback op amp critically important for the OPA3684. External layout capacitance in excess of 2pF will start to peak the frequency response. This peaking can be easily reduced by increasing the feedback resistor value—but it is preferable, ...

  • Page 18

    ... ADC—including additional external capacitance which may be recommended to im- prove ADC linearity. A high-speed, high open-loop gain amplifier like the OPA3684 can be very susceptible to de- creased stability and closed-loop response peaking when a capacitive load is placed directly on the output pin. When the amplifier’ ...

  • Page 19

    ... Equation Evaluating these two equations for the OPA3684 circuit and component values presented in Figure 1 will give a total output spot noise voltage of 16.3nV/ Hz and a total equiva- lent input spot noise voltage of 8.1nV/ Hz. This total input referred spot noise voltage is higher than the 3 ...

  • Page 20

    ... Figure 13. When disabled, the output and input nodes high impedance state. If the OPA3684 is operating in a gain of +1 (with a 800 feedback resistor still required for stability), this will show a very high impedance (1.7pF || the output and exceptional signal isolation ...

  • Page 21

    ... With a characteristic board trace impedance defined based on board material and trace dimensions, a matching series resistor into the trace from the output of the OPA3684 is used, as well as a terminating shunt resistor at the input of the destination device. Remember also that the terminating impedance will be the parallel combination of the shunt resistor and the input impedance of the destination device ...

  • Page 22

    ... INPUT AND ESD PROTECTION The OPA3684 is built using a very high-speed complemen- tary bipolar process. The internal junction breakdown volt- ages are relatively low for these very small geometry devices. These breakdowns are reflected in the Absolute Maximum Ratings table where an absolute maximum 13V across the supply pins is reported ...

  • Page 23

    ... B 16 Design-In Tools 23 Applications Information NOTE: Page numbers for previous revisions may differ from page numbers in the current version. OPA3684 SBOS241C Revision History DESCRIPTION Changed Storage Temperature Range from +125C +125C. Added minimum supply voltage. Demonstration fixture numbers changed. ...

  • Page 24

    ... OPA3684IDBQT ACTIVE SSOP/QSOP OPA3684IDBQTG4 ACTIVE SSOP/QSOP OPA3684IDG4 ACTIVE SOIC OPA3684IDR ACTIVE SOIC OPA3684IDRG4 ACTIVE SOIC (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. ...

  • Page 25

    TI and TI suppliers consider certain information to be proprietary, and thus CAS ...

  • Page 26

    ... TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Type Drawing OPA3684IDBQT SSOP/ DBQ QSOP OPA3684IDR SOIC PACKAGE MATERIALS INFORMATION Pins SPQ Reel Reel Diameter Width (mm) W1 (mm) 16 250 180.0 12 2500 330.0 16.4 Pack Materials-Page ...

  • Page 27

    ... Device Package Type OPA3684IDBQT SSOP/QSOP OPA3684IDR SOIC PACKAGE MATERIALS INFORMATION Package Drawing Pins SPQ Length (mm) DBQ 16 250 D 14 2500 Pack Materials-Page 2 17-Dec-2011 Width (mm) Height (mm) 210.0 185.0 35.0 346.0 346.0 33.0 ...

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    ... Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’ ...