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OPA2683

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.

SBOS244H – MAY 2002 – REVISED JULY 2009

Very Low-Power, Dual, Current-Feedback

Operational Amplifier

FEATURES

● REDUCED BANDWIDTH CHANGE VERSUS GAIN

● 150MHz BANDWIDTH G = +2

● > 80MHz BANDWIDTH TO GAIN > +10

● LOW DISTORTION: < –65dBc at 5MHz

● HIGH OUTPUT CURRENT: 110mA

● SINGLE-SUPPLY OPERATION: +5V to +12V

● DUAL-SUPPLY OPERATION: ±2.5V to ±6V

● LOW SUPPLY CURRENT: 1.9mA Total

● POWER SHUTDOWN VERSION: MSOP-10

V+

V–

ERR

(S)

ERR

Low-Power Amplifier

U.S. Patent No. 6,724,260

DESCRIPTION

The OPA2683 provides a new level of performance for dual, very

low-power, wideband, current-feedback amplifiers. This CFB

PLUS

amplifier is among the first to use an internally closed-loop input

buffer stage that significantly enhances performance over earlier

low-power, current-feedback (CFB) amplifiers. This new archi-

tecture provides many of the advantages of a more ideal CFB

amplifier while retaining the benefits of very low-power operation.

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 gives excep-

tional bandwidth retention to much higher gains and improved

harmonic distortion over earlier solutions limited by inverting input

linearity. Beyond simple high gain applications, the OPA2683

CFB

PLUS

amplifier can allow the gain setting element to be set with

considerable freedom from amplifier bandwidth interaction. This

APPLICATIONS

● LOW-POWER BROADCAST VIDEO DRIVERS

● µPOWER ACTIVE FILTERS

● SHORT-LOOP ADSL CO DRIVERS

● MULTICHANNEL SUMMING AMPLIFIERS

● PROFESSIONAL CAMERAS

● DIFFERENTIAL ADC INPUT DRIVERS

flexibility allows frequency response peaking elements to be

added, multiple input inverting summing circuits to have greater

bandwidth, and low-power differential line drivers to meet the

demanding requirements of DSL.

The output capability for the OPA2683 also sets a new mark in

performance for very low-power, current-feedback amplifiers. De-

livering a full ±4V

swing on ±5V supplies, the OPA2683 also has

the output current to support this swing into a 100Ω load. This

minimal output headroom requirement is complemented by a

similar 1.2V input stage headroom, giving exceptional capability for

single +5V operation.

The OPA2683’s low 1.9mA total 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. Further system power reduction is possible using

the shutdown feature of the MSOP-10 package.

–3

–6

–9

–12

–15

–18

Frequency (Hz)

1 20010 100

NONINVERTING SMALL-SIGNAL

FREQUENCY RESPONSE

Normalized Gain (dB)

G = 100

G = 50

G = 10

G = 1

G = 2

= 953Ω

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.

All trademarks are the property of their respective owners.

www.ti.com

Summary of content (35 pages)

PAGE 1
OPA OPA2683 2683 OPA2 683 www.ti.com SBOS244H – MAY 2002 – REVISED JULY 2009 Very Low-Power, Dual, Current-Feedback Operational Amplifier FEATURES APPLICATIONS ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● REDUCED BANDWIDTH CHANGE VERSUS GAIN 150MHz BANDWIDTH G = +2 > 80MHz BANDWIDTH TO GAIN > +10 LOW DISTORTION: < –65dBc at 5MHz HIGH OUTPUT CURRENT: 110mA SINGLE-SUPPLY OPERATION: +5V to +12V DUAL-SUPPLY OPERATION: ±2.5V to ±6V LOW SUPPLY CURRENT: 1.
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ELECTROSTATIC DISCHARGE SENSITIVITY ABSOLUTE MAXIMUM RATINGS(1) Power Supply ............................................................................... ±6.5VDC Internal Power Dissipation ...................................... See Thermal Analysis Differential Input Voltage .................................................................. ±1.2V Input Voltage Range ............................................................................ ±VS Storage Temperature Range: ID, IDCN ......................
PAGE 3
ELECTRICAL CHARACTERISTICS: VS = ±5V Boldface limits are tested at +25°C. RF = 953Ω, RL = 1kΩ, and G = +2 (see Figure 1 for AC performance only), unless otherwise noted. OPA2683ID, IDCN, IDGS TYP PARAMETER AC PERFORMANCE (see Figure 1) Small-Signal Bandwidth (VO = 0.5VPP) Bandwidth for 0.
PAGE 4
ELECTRICAL CHARACTERISTICS: VS = +5V Boldface limits are tested at +25°C. RF = 1.2kΩ, RL = 1kΩ, and G = +2 (see Figure 3 for AC performance only), unless otherwise noted. OPA2683ID, IDCN, IDGS TYP PARAMETER AC PERFORMANCE (see Figure 3) Small-Signal Bandwidth (VO = 0.2VPP) Bandwidth for 0.
PAGE 5
TYPICAL CHARACTERISTICS: VS = ±5V TA = +25°C, G = +2, RF = 953Ω, and RL = 1kΩ, unless otherwise noted. NONINVERTING SMALL-SIGNAL FREQUENCY RESPONSE INVERTING SMALL-SIGNAL FREQUENCY RESPONSE 6 6 G = 10 G = 1 3 VO = 0.
PAGE 6
TYPICAL CHARACTERISTICS: VS = ±5V (Cont.) TA = +25°C, G = +2, RF = 953Ω, and RL = 1kΩ, unless otherwise noted. HARMONIC DISTORTION vs LOAD RESISTANCE HARMONIC DISTORTION vs FREQUENCY –50 –50 VO = 2VPP f = 5MHz G = +2 –60 –65 VO = 2VPP RL = 1kΩ –55 Normalized Distortion (dB) Harmonic Distortion (dBc) –55 2nd-Harmonic –70 –75 –80 3rd-Harmonic –85 –60 –65 –70 –75 2nd-Harmonic –80 –85 –90 See Figure 1 –90 100 3rd-Harmonic See Figure 1 –95 0.
PAGE 7
TYPICAL CHARACTERISTICS: VS = ±5V (Cont.) TA = +25°C, G = +2, RF = 953Ω, and RL = 1kΩ, unless otherwise noted. 2-TONE, 3RD-ORDER INTERMODULATION DISTORTION INPUT VOLTAGE AND CURRENT NOISE DENSITY –45 3rd-Order Spurious Level (dBc) Inverting Current Noise 11.6pA/√Hz Noninverting Current Noise 5.2pA/√Hz 10 Voltage Noise 4.4nV/√Hz 1 fO = 20MHz –50 +5V –55 PI 50Ω –60 1kΩ –5V 953Ω –65 –70 953Ω fO = 5MHz –75 –80 fO = 1MHz –85 –90 100 1k 10k 100k 1M 0.
PAGE 8
TYPICAL CHARACTERISTICS: VS = ±5V (Cont.) TA = +25°C, G = +2, RF = 953Ω, and RL = 1kΩ, unless otherwise noted. OUTPUT CURRENT AND VOLTAGE LIMITATIONS COMPOSITE VIDEO DIFFERENTIAL GAIN/PHASE 2 0.10 dG L 3 0.15 =1 00Ω 1W Power Limit R 4 VO (V) = RL 50 Ω 1 0 –1 –2 0.05 –3 dP –4 1 2 3 4 Number of 150Ω Video Loads –150 0 IO (mA) TYPICAL DC DRIFT OVER TEMPERATURE SUPPLY AND OUTPUT CURRENT vs TEMPERATURE –100 –50 50 100 150 200 4 2.
PAGE 9
TYPICAL CHARACTERISTICS: VS = ±5V (Cont.) TA = +25°C, G = +2, RF = 953Ω, and RL = 1kΩ, unless otherwise noted. 8.0 3.2 6.4 6.4 6.4 2.4 4.8 4.8 4.8 1.6 3.2 0.8 1.6 0 0 Output Voltage Right Scale –0.8 –1.6 See Figure 1 –1.6 –2.4 –3.2 –4.8 Input Voltage Left Scale –3.2 –4.0 Input Voltage (1.6V/div) 8.0 3.2 3.2 Output Voltage Right Scale 1.6 0 –1.6 –1.6 –3.2 –3.2 –4.8 –6.4 –6.4 –8.0 –8.0 –8.
PAGE 10
TYPICAL CHARACTERISTICS: VS = ±5V (Cont.) TA = +25°C, G = +2, RF = 953Ω, and RL = 1kΩ, unless otherwise noted. DISABLED FEEDTHRU –40 G = +2 VDIS = 0V Feedthru (dB) –50 Each Channel –60 –70 –80 –90 See Figure 1 –100 0.1 1 10 100 Frequency (MHz) 10 OPA2683 www.ti.
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TYPICAL CHARACTERISTICS: VS = +5V TA = +25°C, VS = 5V, G = +2, RF = 1.2kΩ, and RL = 1kΩ, unless otherwise noted.
PAGE 12
TYPICAL CHARACTERISTICS: VS = +5V (Cont.) TA = +25°C, VS = 5V, G = +2, RF = 1.2kΩ, and RL = 1kΩ, unless otherwise noted. HARMONIC DISTORTION vs FREQUENCY HARMONIC DISTORTION vs LOAD RESISTANCE –50 –50 f = 5MHz VO = 2VPP VO = 2VPP RL = 1kΩ Harmonic Distortion (dBc) Harmonic Distortion (dBc) –55 2nd-Harmonic –60 –65 3rd-Harmonic –70 –75 –80 –60 2nd-Harmonic –70 3rd-Harmonic –80 –85 See Figure 3 See Figure 3 –90 –90 100 0.
PAGE 13
APPLICATIONS INFORMATION LOW-POWER, CURRENT-FEEDBACK OPERATION The dual channel OPA2683 gives a new level of performance in low-power, current-feedback op amps. Using a new input stage buffer architecture, the OPA2683 CFBPLUS amplifier holds nearly constant AC performance over a wide gain range. This closed-loop internal buffer gives a very low and linearized impedance at the inverting node, isolating the amplifier’s AC performance from gain element variations.
PAGE 14
into this midpoint voltage bias. The input voltage can swing to within 1.25V of either supply pin, giving a 2.5VPP input signal range centered between the supply pins. The input impedance of Figure 3 is set to give a 50Ω input match. If the source does not require a 50Ω match, remove this and drive directly into the blocking capacitor. The source will then see the 5kΩ load of the biasing network.
PAGE 15
This approach provides for a source termination impedance that is independent of the signal gain. For instance, simple differential filters may be included in the signal path right up to the noninverting inputs without interacting with the gain setting. The differential signal gain for the circuit of Figure 5 is: (1) AD = 1 + 2 • RF /RG Since the OPA2683 is a CFBPLUS amplifier, its bandwidth is principally controlled with the feedback resistor value; see Figure 5 for the recommended value of 953Ω.
PAGE 16
of Figure 9 designs the filter for a differential gain of 5 using the OPA2683. The resistor values have been adjusted slightly to account for the amplifier bandwidth effects. SINGLE TO DIFFERENTIAL CONVERSION 24 While this circuit is bipolar, using ±5V supplies, it can easily be adapted to single-supply operation. This is typically done by providing a supply midpoint reference at the noninverting inputs, then adding DC blocking caps at each input and in series with the amplifier gain resistor, RG.
PAGE 17
SINGLE-SUPPLY, HIGH GAIN DIFFERENTIAL ADC DRIVER +5V Where a very low-power differential I/O interface to a moderate performance ADC is required, the circuit of Figure 11 may be considered. The circuit builds on the inverting differential I/O configuration of Figure 6 by adding the input transformer and the output low-pass filter.
PAGE 18
DESIGN-IN TOOLS OPERATING SUGGESTIONS DEMONSTRATION FIXTURES SETTING RESISTOR VALUES TO OPTIMIZE BANDWIDTH Two printed circuit boards (PCBs) are available to assist in the initial evaluation of circuit performance using the OPA2683 in its two package options. Both of these are offered free of charge as unpopulated PCBs, delivered with a user’s guide. The summary information for these fixtures is shown in Table I.
PAGE 19
The buffer gain is typically very close to 1.00 and is normally neglected from signal gain considerations. It will, however, set the CMRR for a single op amp differential amplifier configuration. For the buffer gain α < 1.0, the CMRR = –20 • log(1 – α). The closed-loop input stage buffer used in the OPA2683 gives a buffer gain more closely approaching 1.00 and this shows up in a slightly higher CMRR than previous current-feedback op amps.
PAGE 20
OUTPUT CURRENT AND VOLTAGE DRIVING CAPACITIVE LOADS The OPA2683 provides output voltage and current capabilities that can support the needs of driving doubly-terminated 50Ω lines. If the 1kΩ load of Figure 1 is changed to a 100Ω load, the total load is the parallel combination of the 100Ω load, and the 1.9kΩ total feedback network impedance. This 95Ω load will require no more than 42mA output current to support the ±4.0V minimum output voltage swing specified for 1kΩ loads.
PAGE 21
DISTORTION PERFORMANCE The OPA2683 provides very low distortion in a low-power part. The CFBPLUS architecture also gives two significant areas of distortion improvement. First, in operating regions where the 2nd-harmonic distortion due to output stage nonlinearities is very low (frequencies < 1MHz, low output swings into light loads) the linearization at the inverting node provided by the CFBPLUS design gives 2nd-harmonic distortions that extend into the –90dBc region.
PAGE 22
The total output spot noise voltage can be computed as the square root of the sum of all squared output noise voltage contributors. Equation 4 shows the general form for the output noise voltage using the terms presented in Figure 14. (4) 2 2 EO =  ENI2 + (IBNR S ) + 4kTRS  NG2 + (IBIRF ) + 4kTRFNG Dividing this expression by the noise gain (NG = (1 + RF /RG)) will give the equivalent input referred spot noise voltage at the noninverting input, as shown in Equation 5.
PAGE 23
The OPA2683 provides very high power gain on low quiescent current levels. When disabled, internal high impedance nodes discharge slowly which, with the exceptional power gain provided, give a self powering characteristic that leads to a slow turn off characteristic. Typical full turn off times to rated 100µA disabled supply current are 60ms. Turn on times are very fast—less than 40ns. b) Minimize the distance (< 0.25") from the power-supply pins to high-frequency 0.1µF decoupling capacitors.
PAGE 24
d) 24 Connections to other wideband devices on the board may be made with short direct traces or through onboard transmission lines. For short connections, consider the trace and the input to the next device as a lumped capacitive load. Relatively wide traces (50mils to 100mils) should be used, preferably with ground and power planes opened up around them. Estimate the total capacitive load and set RS from the plot of recommended Rs vs CLOAD.
PAGE 25
Revision History DATE REVISION PAGE 7/09 H 2 7/08 G 2 SECTION DESCRIPTION Package/Ordering Information Changed package markings for D (SO-8) and DGS (MSOP-10) packages. Absolute Maximum Ratings Changed minimum storage temperature from −40°C to −65°C. NOTE: Page numbers for previous revisions may differ from page numbers in the current version. OPA2683 SBOS244H www.ti.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 31-Oct-2013 (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line.
PAGE 28
PACKAGE MATERIALS INFORMATION www.ti.com 12-Aug-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ OPA2683IDCNR SOT-23 8 3000 180.0 OPA2683IDCNT SOT-23 DCN 8 250 OPA2683IDGST VSSOP DGS 10 250 DCN Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) 8.4 3.2 3.1 1.39 4.0 180.0 8.4 3.2 3.1 1.39 180.0 12.4 5.3 3.4 1.4 Pack Materials-Page 1 W Pin1 (mm) Quadrant 8.0 Q3 4.0 8.0 Q3 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 12-Aug-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) OPA2683IDCNR SOT-23 DCN 8 3000 210.0 185.0 35.0 OPA2683IDCNT SOT-23 DCN 8 250 210.0 185.0 35.0 OPA2683IDGST VSSOP DGS 10 250 210.0 185.0 35.
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