Dual, Wide Bandwidth OPERATIONAL TRANSCONDUCTANCE AMPLIFIER

OPA2662 OPA2662

OPA2662

FEATURES DESCRIPTION ● 370MHz BANDWIDTH The OPA2662 is a versatile driver device for ultra ● 58mA/ns SLEW RATE wide-bandwidth systems, including high-resolution ● ± video, RF and IF circuitry, communications and test HIGH OUTPUT CURRENT: 75mA equipment. The OPA2662 includes two power volt- ● 400Mbit/s DATA RATE age-controlled current sources, or operational ● VOLTAGE-CONTROLLED CURRENT transconductance amplifiers (OTAs), in a 16-pin DIP SOURCE or SOL-16 package and is specified for the extended ° ° ● ENABLE/DISABLE FUNCTION industrial temperature range (–40 C to +85 C). The output current is zero-for-zero differential input voltage. The OTAs provide a 250MHz large-signal bandwidth, a 58mA/ns slew rate, and each current source APPLICATIONS delivers up to ±75mA output current. ● HEAD DRIVE AMPLIFIER FOR ANALOG/ The transconductance of both OTAs can be adjusted

DIGITAL VIDEO TAPES AND DATA RE- between pin 5 and –VCC by an external resistor, CORDERS allowing bandwidth, quiescent current, harmonic dis- ● LED AND LASER DIODE DRIVER tortion and gain trade-offs to be optimized. The output current can be set with a degeneration resistor ● HIGH CURRENT VIDEO BUFFER OR LINE between the emitter and GND. The current mirror DRIVER ratio between the collector and emitter currents is ● RF OUTPUT STAGE DRIVER fixed to three. Switching stages compatible to logic ● HIGH DENSITY DISK DRIVES TTL levels make it possible to turn each OTA sepa- rately on within 30ns and off within 200ns at full power. +VCCOUT I (mA) (16) 80

70 IC 60

20 I B E C E +1 (2,7) (10,15) (11,14)

Ð1 Ð0.8 Ð0.6 Ð0.4 0.2 0.4 0.6 0.8 1 VIN (V) EN Ð10

Ð20 (3, 6) Ð30

Ð40

Ð50

(9) Ð60 ÐV CCOUT Ð70 OTA Transfer Ð80 1/2 OPA2662 Characteristics

International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 • Twx: 910-952-1111 Internet: http://www.burr-brown.com/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132

SBOS011 SPECIFICATIONS ELECTRICAL DC-SPECIFICATIONS ± Ω ° At VCC = 5V, RQ = 750 , TA = +25 C, and configured as noted under “CONDITIONS”. OPA2662AP, AU

PARAMETER CONDITIONS MIN TYP MAX UNITS OTA INPUT OFFSET VOLTAGE Ω Ω ± Initial RE = 50k , RC = 40 12 30 mV vs Temperature 35 µV/°C ± ± Ω Ω vs Supply (tracking) VCC = 4.5V to 5.5V, RE = 50k , RC = 1k 27 dB Ω Ω vs Supply (non-tracking) VCC = +4.5V to +5.5V, RE = 50k , RC = 1k 15 dB Ω Ω vs Supply (non-tracking) VCC = –4.5V to –5.5V, RE = 50k , RC = 1k 40 dB Matching 2 ±7mV OTA B-INPUT BIAS CURRENT Ω Ω µ Initial RE = 100 , RC = 40 1 –1/+5 A vs Temperature –5 nA/°C ± ± Ω Ω vs Supply (tracking) VCC = 4.5V to 5.5V, RE = 50k , RC = 1k 60 nA/V Ω Ω vs Supply (non-tracking) VCC = +4.5V to +5.5V, RE = 50k , RC = 1k 160 nA/V Ω Ω vs Supply (non-tracking) VCC = –4.5V to –5.5V, RE = 50k , RC = 1k 40 nA/V Matching 0.2 ±1 µA Ω Ω OTA C-OUTPUT BIAS CURRENT RE = 100 , RC = 1k Initial 0.5 –0.5/+1.5 mA vs Temperature 1.5 µA/°C ± ± µ vs Supply (tracking) VCC = 4.5V to 5.5V 72 A/V µ vs Supply (non-tracking) VCC = +4.5V to +5.5V 236 A/V µ vs Supply (non-tracking) VCC = –4.5V to –5.5V 92 A/V Matching 0.06 ±0.5 mA B-INPUT IMPEDANCE ± Ω Impedance IQ = 17mA 4.5 || 1.5 M || pF OTA INPUT NOISE Input Noise Voltage Density f = 20kHz to 100MHz 4.4 nV/√Hz Output Noise Current Density 0.09 nA/√Hz √ Signal-to-Noise Ratio S/N = 20 log • (0.7/VN • 5MHz) 97 dB OTA C-RATED OUTPUT ± Ω Ω± Output Voltage Compliance IC = 5mA, RE = 100 , RC = 1k 3.4 V Ω Ω± Output Current RC = 40 , RE = 100 75 mA ± VIN = 3V ± Ω Output Impedance, rC IQ = 17mA 4.5 || 6.5 k || pF OTA E-RATED OUTPUT Ω, Ω± Voltage Output RE = 100 RC = 40 3.0 V Ω, Ω DC Current Output RE = 100 RC = 40 ± ± VIN = 4V 25 mA ± Voltage Gain VIN = 2.5V Ω RE = 100 0.86 V/V Ω RE = 50k 0.98 V/V ± Ω Output Impedance, rE IQ = 17mA 16 || 2.2 || pF POWER SUPPLY Ω, Ω± ± Rated Voltage RE = 50k RC = 1k 4.5 5.5 VDC Ω Ω± ± Derated Performance RE = 50k , RC = 40 3 6 VDC Ω Ω Ω Positive Quiescent Current RQ = 750 , RE = 50k , RC = 1k , +15 +17 +18 mA for both OTAs(4) Both Channels Enabled Ω Ω Ω Positive Quiescent Current RQ = 750 , RE = 50k , RC = 1k ,+4mA for both OTAs(4) Both Channels Disabled Quiescent Current Range Programmable Ω Ω± ± RQ = 3k to 30 3 65 mA TEMPERATURE RANGE Specification Ambient Temperature –40 +85 °C θ Thermal Resistance, JA AP 90 °C/W AU 100 °C/W

NOTES: (1) Characterization sample. (2) “Typical Values” are Mean values. The average of the two amplifiers is used for amplifier specific parameters. (3) “Min” and “Max” Values are mean ±3 Standard Deviations. Worst case of the two amplifiers (Mean ±3 Standard Deviations) is used for amplifier specific parameters. (4) – + I Q typically 2mA less than I Q due to OTA C-Output Bias Current and TTL Select Circuit Current.

The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support devices and/or systems.

OPA2662 2 SPECIFICATIONS (CONT) ELECTRICAL AC-SPECIFICATION ± Ω ± Ω ± Ω Ω, ° Typical at VCC = 5VDC, RQ = 750 , IC = 37.5mA (VIN = 2.5Vpp, RE = 100 ), IC = 75mA (VIN = 2.5Vpp, RE = 50 ), RSOURCE = 50 and TA = +25 C, unless otherwise noted.

OPA2662AP, AU PARAMETER CONDITIONS MIN TYP MAX UNITS FREQUENCY DOMAIN LARGE SIGNAL BANDWIDTH ± Ω Ω IC = 37.5mA RE = 100 , RC = 50 150 MHz ± Ω Ω IC = 75mA RE = 100 , RC = 25 200 MHz ± Ω Ω IC = 37.5mA (Optimized) RE = 100 , RC = 50 , CE = 5.6pF 370 MHz ± Ω Ω IC = 75mA (Optimized) RE = 100 , RC = 25 , CE = 5.6pF 250 MHz Ω Ω GROUP DELAY TIME RE = 100 , RC = 50 Measured Input to Output B to E 1.2 ns (Demo Board Used) B to C 2.5 ns HARMONIC DISTORTION ± Second Harmonic f = 10MHz, IC = 37.5mA –31 dBc Third Harmonic –37 dBc ± Second Harmonic f = 10MHz, IC = 75mA –33 dBc Third Harmonic –32 dBc ± Second Harmonic f = 30MHz, IC = 37.5mA –29 dBc Third Harmonic –32 dBc ± Second Harmonic f = 30MHz, IC = 75mA –30 dBc Third Harmonic –25 dBc ± Second Harmonic f = 50MHz, IC = 37.5mA –31 dBc Third Harmonic –30 dBc ± Second Harmonic f = 50MHz, IC = 75mA –28 dBc Third Harmonic –23 dBc CROSSTALK Typical Curve Number 3 ± IC = 37.5mA, f = 30MHz –51 dB ± IC = 75mA, f = 30MHz –56 dB FEEDTHROUGH Ω Off Isolation RE = 100 , f = 30MHz –90 dB Ω RE = 50 , f = 30MHz –90 dB TIME DOMAIN Rise Time 10% to 90%

75mA Step IC 2ns 150mA Step IC 2.6 ns Slew Rate IC = 75mA 37.5 mA/ns IC = 150mA 58 mA/ns

CHANNEL SELECTION

OPA2662AP, AU PARAMETER CONDITIONS MIN TYP MAX UNITS

ENABLE INPUTS

Logic 1 Voltage 2VCC + 0.6 V Logic 0 Voltage 0 0.8 V µ Logic 1 Current VSEL = 2.0V to 5V 0.8 1.1 10 A µ Logic 0 Current VSEL = 0V to 0.8V –1 0.05 A

SWITCHING CHARACTERISTICS IC = 150mAp-p, f = 5MHz EN to Channel ON Time 90% Point of VO = 1Vp-p 30 ns EN to Channel OFF Time 10% Point of VO = 1Vp-p 200 ns Switching Transient, Positive (Measured While Switching 30 mV Switching Transient, Negative Between the Grounded Channels) –80 mV

3 OPA2662 SPECIFICATIONS (CONT) ELECTRICAL (Full Temperature Range –40°C to +85°C) ± Ω At VCC = 5VDC, RQ = 750 , TA = TMIN to TMAX, unless otherwise noted, and configured as noted under “CONDITIONS”.

OPA2662AP, AU PARAMETER CONDITIONS MIN TYP MAX UNITS Ω, Ω OTA INPUT OFFSET VOLTAGE RE = 50k RC = 40 Initial 12 ±36 mV Matching 2 ±7.2 mV Ω, Ω OTA INPUT BIAS CURRENT RE = 100 RC = 40 Initial –1.9 1 5.9 µA Matching –1.2 0.2 1.2 µA OTA TRANSCONDUCTANCE

Transconductance IC = 75mA, RE = 0 580 610 mA/V OTA C-RATED OUTPUT ± Ω, Ω± Output Voltage Compliance IC = 5mA, RE = 100 RC = 16 3.2 V POWER SUPPLY (4) Ω Ω Ω Positive Quiescent Current for both OTAs RQ = 750 , RE = 50k , RC = 1k , +8 +17 +25 mA Both Channels Selected

PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS

Top View SOL-16/DIP Power Supply Voltage ...... ±6V (1) ± ± Input Voltage ...... VCC to 0.7V Operating Temperature ...... –40°C to +85°C Storage Temperature ...... –40°C to +125°C +V 1 16 CC +VCCOUT Junction Temperature ...... +175°C Lead Temperature (soldering, 10s) ...... +300°C B Digital Input Voltages (EN1, EN2) ...... –0.5 to +VCC +0.7V 1 2 15 E1 NOTE: (1) Inputs are internally diode-clamped to ±V . OTA1 CC EN 1 3 14 C1 Logic PACKAGE/ORDERING INFORMATION GND 4 13 NC PTAT PACKAGE Supply DRAWING TEMPERATURE I Adjust 5 12 NC Q PRODUCT PACKAGE NUMBER(1) RANGE Logic OPA2662AP 16-Pin Plastic DIP 180 –40°C to +85°C EN2 6 11 C OTA2 2 OPA2662AU SOL-16 Surface Mount 211 –40°C to +85°C NOTE: (1) For detailed drawing and dimension table, please see end of data B 7 10 2 E2 sheet, or Appendix C of Burr-Brown IC Data Book.

ÐV CC 8 9 ÐVCCOUT OPA2662

ELECTROSTATIC DISCHARGE SENSITIVITY Any integrated circuit can be damaged by ESD. Burr-Brown recommends that all integrated circuits be handled with ap- propriate precautions. ESD can cause damage ranging from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet published specifications. Burr-Brown’s standard ESD test method consists of five 1000V positive and negative discharges (100pF in series with 1.5kΩ) applied to each pin.

OPA2662 4 TYPICAL PERFORMANCE CURVES ± Ω ° At VCC = 5V, RQ = 750 , and TA = +25 C, unless otherwise specified.

OTA B TO E-INPUT OFFSET VOLTAGE OTA B-INPUT RESISTANCE vs TEMPERATURE vs TOTAL QUIESCENT CURRENT 15 18

16 14 Ω) 14 13 12

12 10

11 8 6 10 4 Input Offset Voltage (mV) Ω RE = 50k

9 Ω OTA B-Input Resistance (M RC = 40 2

8 0 Ð50 Ð25 0 25 50 75 100 7 12 17 22 27 32 37 42 47

Temperature (¡C) Total Quiescent Current, IQ (±mA)

OTA C-OUTPUT BIAS CURRENT vs TEMPERAURE OTA B-INPUT BIAS CURRENT vs TEMPERATURE 0.70 1.5

0.65

0.60 1.3

0.55

0.50 1.1

0.45

0.40 0.9 B-Input Bias Current (µA) Output Bias Current (mA) 0.35

0.30 0.7 Ð50 Ð25 0 25 50 75 100 Ð50 Ð25 0 25 50 75 100 Temperature (¡C) Temperature (C¡)

OTA E-OUTPUT RESISTANCE OTA C-OUTPUT RESISTANCE vs TOTAL QUIESCENT CURRENT vs TOTAL QUIESCENT CURRENT 50 9 )

) 45

Ω 8 Ω ( (k E 40 C 7 35 6 30 5 25 4 20 3 15 10 2

OTA E-Output Resistance r 1 5 OTA C-Output Resistance, r 0 0 74712 17 22 2732 37 42 7 12 17 22 27 32 37 42 47

Total Quiescent Current, IQ (±mA) Total Quiescent Current, IQ (±mA)

5 OPA2662 TYPICAL PERFORMANCE CURVES (CONT) ± Ω ° At VCC = 5V, RQ = 750 , and TA = +25 C, unless otherwise specified.

TOTAL QUIESCENT CURRENT vs RQ QUIESCENT CURRENT CHANGE vs TEMPERATURE 70 24

60 22 (±mA) Q 50 20 Typical 40 18

30 16

20 14 Quiescent Current (mA)

10 12 Total Quiescent Current, I

0 10 10 100 1k 10k Ð60 Ð40 Ð20 0 20 4060 80 100 Ω RQ - Resistor Value ( ) Temperature (¡C)

OTA TRANSFER CHARACTERISTICS vs RE IC/IE TRANSFER CURVE 120 100 Ω RE = 25 75 80 50 R = 33Ω 40 E 25 Ω 0 RE = 50 0 Ω RE = 100 Ð25 Ð40 Ð50 Ω OTA C-Output Current (mA) OTA C-Output Current (mA) Ð80 RC = 10 V = 1.9Vp-p Ð75 IN Ω, Ω RE = 33 RC = 11 Ð120 Ð100 Ð0.95 0 0.95 Ð25 Ð20 Ð15 Ð10 Ð5 0 5 10 15 20 25 30 Input Voltage (V) OTA E-Output Current (mA)

OTA TRANSFER CHARACTERISTICS vs TOTAL QUIESCENT CURRENT TRANSCONDUCTANCE vs VIN vs IQ 700 100 80 I = ±34mA 600 Q I = 65mA 60 Q I = ±65mA 500 40 Q I = 34mA Q 20 400 0 IQ = 17mA IQ = ±17mA I = ±8mA 300 Ð20 Q I = 8mA Ð40 200 Q Ð60 OTA C-Output Current (mA) 100 Ω Ð80 RE = 0 OTA Transconductance gm (mA/V) 0 Ð100 Ð200 Ð150 Ð100 Ð50 0 50 100 150 200 Ð200 Ð100 0 100 200 Input Voltage (mV) Input Voltage (mV)

OPA2662 6 TYPICAL PERFORMANCE CURVES (CONT) ± Ω ± Ω ± Ω ° At VCC = 5V, RQ = 750 , IC = 37.5mA (RE = 100 , VIN = 2.5Vp-p), IC = 75mA (RE = 50 , VIN = 2.5Vp-p), and TAMB = +25 C, unless otherwise noted.

BANDWIDTH vs OUTPUT CURRENT OPEN-LOOP GAIN vs FREQUENCY 5 80

IQ = ±17mA 0 60 IQ = ±8mA IC = ±75mA IC = ±37.5mA Ω Ω RC = 15 RC = 30 IQ = ±34mA Ð5 Ω Ω RE = 25 RE = 50 40

Gain (dB) Test Circuit Ð10 Gain (dB) 50Ω 100Ω DUT BUF601 180Ω 50Ω 20 +1 Ð15 50Ω

Ð20 0 1M 10M 100M 1G 100k 300k 1M 3M 10M 30M 100M Frequency (Hz) Frequency (Hz)

OTA LARGE SIGNAL PULSE RESPONSE OTA LARGE SIGNAL PULSE RESPONSE vs OUTPUT CURRENT vs TOTAL QUIESCENT CURRENT 2.0 100

ICMAX = ±37mA 1.0 Ω 50 RE = 100

IQ = ±34mA ICMAX = ±75mA 0 Ω 0 RE = 50

I = ±8mA Q I = ±17mA Ð1.0 Ð5 Q OTA C-Output Voltage (V) OTA C-Output Current (mA) I = ±17mA Ω, Ω Q RC = 10 RE = 50 tRISE = tFALL = 1ns (Generator) Ð2.0 Ð100 0 50 100 150 200 0 10 20 30 40 50 Time (ns) Time (ns)

OTA LARGE SIGNAL PULSE RESPONSE OPTIMIZED FREQUENCY RESPONSE vs OUTPUT VOLTAGE vs OUTPUT VOLTAGE 1.0 20 Ω RC = 10 6Vp-p

0.5 0 Ω RC = 30 3Vp-p 1.4Vp-p 0.6Vp-p Test Circuit 0 Ð20 Ω VIN 100 V Gain (dBm) OUT

V = 2.7Vp-p Test Circuit IN Ð0.5 100Ω Ð40 R C V 50Ω OUT Ω OTA C-Output Voltage (V) 100 6.8pF 12Ω 50Ω RE CE 50Ω IQ = ±17mA Ð1.0 Ð60 0 50 100 150 200 0.1M1M 10M 100M 1G Time (ns) Frequency (Hz)

7 OPA2662 TYPICAL PERFORMANCE CURVES (CONT) ± Ω ± Ω ± Ω ° VCC = 5V, RQ = 750 , IC = 37.5mA (RE = 100 , VIN = 2.5Vp-p), IC = 75mA (RE = 50 , VIN = 2.5Vp-p), and TA = +25 C, unless otherwise specified.

tOFF Worst Case EN-TIME SWITCHING TRANSIENT 250

4 200

4 75 2 150

2 0 100

0 0 50

–2 0 EN Voltage (V) EN Voltage (V)

–4 –75 –50 Output Voltage (mV) OTA C-Output Current (mA) –100

fIN = 5MHz Both Inputs Connected –150 0 250 500 0 250 500 with 150Ω tON Time (ns) to GND Time (ns)

CROSSTALK vs FREQUENCY OFF ISOLATION vs FREQUENCY 20 20

0 0

VIN VIN Ð20 Ð20 1

Ð40 Ð40 2 3 C1 EN

Crosstalk (dB) 1 Ð60 100Ω IC1 = 150mAp-p Ð60 VIN OTA1 Off Isolation (dB) Ω B1 50 E1 VOUT CURVE EN1 EN2 Ω C2 100 Ω 1 1 1 OTA2 50 Ð80 2 1 0 B2 E2 Ð80 EN2 3 0 1 OPA2662 50Ω 50Ω Ð100 Ð100 300k1M 10M 100M 1G 300k 1M 10M 100M 1G Frequency (Hz) Frequency (Hz)

HARMONIC DISTORTION vs FREQUENCY OTA TRANSFER CHARACTERISTICS Ð20 80

60 Ð25 I = ±34mA 2nd Harmonic 40 Q Ð30 20 IQ = ±65mA 3rd Harmonic IQ = ±8mA Ð35 0 IQ = ±17mA Ð20 Ð40 I = ±17mA Q Ð40 R = 100Ω

Harmonic Distortion (dBc) E

Ð45 Ω OTA C-Output Current (mA) RC = 50 Ð60 IC = 75mAp-p Ð50 Ð80

1.0M 3.0M10M 30M 100M ÐVIN 0+VIN Frequency (Hz) Variable Input Voltage (mV) for ±75mA Collector Current at the End Points

OPA2662 8 TYPICAL PERFORMANCE CURVES (CONT) ± Ω Ω ± Ω ° At VCC = 5V, RQ = 750 , (RE = 100 , VIN = 2.5Vp-p), IC = 75mA (RE = 50 , VIN = 2.5Vp-p), and TA = +25 C, unless otherwise specified.

OTA SPECTRAL NOISE DENSITY BUFFER SPECTRAL NOISE DENSITY Ð124 140 124 140

Ð134 44 Ð134 44 Hz) Hz) Hz) Hz) √ √ √ √

Test Circuit DUT Ð144 + 14 Ð144 14 V N I = ±17mA IQ = ±34mA 150Ω Ð Q 50Ω OTA Noise (nV/

OTA Noise (dBm/ Ð154 4.4 Ð154 4.4 Buffer Noise (nV/ IQ = ±34mA Buffer Noise (dBm/ 150Ω IQ = ±8mA I = ±17mA V Q N IQ = ±8mA Ð164 1.4 Ð164 1.4 100 1k 10k 100k 1M 100 1k 10k100k 1M Frequency (Hz) Frequency (Hz)

BUFFER TRANSFER FUNCTION, B to E BUFFER OUTPUT GAIN ERROR, B to E 4 50 R = 100Ω 45 Ð40¡C 3 E I = ±17mA Q 40 2 35 1 30 0 25 85¡C 20 Ð1 Gain Error (%) 15 Ð2

Buffer Output Voltage (V) 10 Ð3 5 Ð4 0 Ð5 Ð4Ð3Ð2Ð1012345 Ð5 Ð4Ð3Ð2Ð1012345 Input Voltage (V) Input Voltage (V)

OTA E-OUTPUT SMALL SIGNAL PULSE RESPONSE OTA E-OUTPUT LARGE SIGNAL PULSE RESPONSE 150 4

100 2 50

0 0

Ð50 Output Voltage (V) Output Voltage (mV) Ð2 Ð100 Ω Ω IQ = ±17mA, tRISE = tFALL = 1ns (Generator), RE = 100 IQ = ±17mA, tRISE = tFALL = 1ns (Generator), RE = 100 Ð150 Ð4 0 20 40 60 80 100 120 0 20 40 60 80 100 120 Time (ns) Time (ns)

9 OPA2662 APPLICATION INFORMATION too, is a voltage-controlled current source. The three OTA terminals are labelled; base (B), emitter (E) and collector ± The OPA2662 typically operates from 5V power supplies (C), calling attention to its similarity to a transistor. The ± ( 6V maximum). Do not attempt to operate with larger OTA sections can be viewed as wide-band, voltage-con- power supply voltages or permanent damage may occur. All trolled, bipolar current sources. The collector current of each inputs of the OPA2662 are protected by internal diode OTA is controlled by the differential voltage between the clamps, as shown in the simplified schematic in Figure 1. high-impedance base and low-impedance emitter. If a cur- These protection diodes can safely, continuously conduct rent flows at the emitter, then the current mirror reflects this 10mA (30mA peak). The input signal current must be current to the high-impedance collector by a fixed ratio of limited if input voltages can exceed the power supply volt- three. Thus, the collector is determined by the product of the ages by 0.7V, as can occur when power supplies are switched base-emitter voltage times the transconductance times the off and a signal source is still present. The buffer outputs E1 current mirror factor. The typical performance curves illus- and E2 are not current-limited or protected. If these outputs trate the OTA open-loop transfer characteristic. Due to the are shorted to ground, high currents could flow. Momentary PTAT (Proportional to Absolute Temperature) biasing, the shorts to ground (a few seconds) should be avoided, but are transconductance is constant vs temperature and can be unlikely to cause permanent damage. adjusted by an external resistor. The typical performance curves show the transfer characteristic for various quiescent currents. While similar to that of a transistor, this character- DISCUSSION OF istic has one essential difference, as can be seen in the PERFORMANCE performance curve: the (sense) of the C output current. This current flows out of the C terminal for positive B-to-E input OTA voltage and into for negative. The two OTA sections of the OPA2662 are versatile driver The OTAs offer many advantages over discrete transistors. devices for wide-bandwidth systems. Applications best suited First of all, they are self-biased and bipolar. The output to this new circuit technology are those where the output current is zero-for-zero differential input voltage. AC inputs signal is current rather than voltage. Such applications in- centered at zero produce an output current that is bipolar and clude driving LEDs, laser diodes, tuning coils, and driver centered at zero. The self-biased OTAs simplify the design transformers. The OPA2662 is also an excellent choice to process and reduce the number of components. It is far more drive the video heads of analog or digital video tape record- linear than a transistor. The transconductance of a transistor ers in broadcast and HDTV-quality or video heads of high- is proportional to its collector current. But since the collector density data recorders. current is dependent upon the signal, it and the The symbol for the OTA sections is similar to that of a transconductance are fundamentally nonlinear. Like transis- bipolar transistor. Application circuits for the OTA look and tor circuits, OTA circuits may also use emitter degeneration operate much like transistor circuits—the bipolar transistor,

+VCC +VCCOUT

(1) (16)

+VCCOUT x1 x3 (16)

EN (3,6)

B E C B (2,7) E (10,15) C (11,14) +1 Control (2,7) (10,15) (11,14) IE 3 x IE

EN (4) Bias (3,6) Circuitry OTA

(9) ÐVCCOUT x1 x3

(8) (9)

IQ Adjust RQ (ext.) ÐVCC ÐVCCOUT (5) Ω RQ = 750 sets IQ to ±17mA for both OTAs.

FIGURE 1. Simplified Block and Circuit Diagram.

OPA2662 10 to reduce the effect that offset voltages and currents might I otherwise have on the DC operating point of the OTA. The C I (mA) C E degeneration resistor may be bypassed by a capacitor to 70 I maintain high AC gain. Other cases may require a capacitor 60 C with less value to optimize high-frequency performance. B 50 The transconductance of the OTA with degeneration can be rE 40 calculated by: E 30 IE = 1 = 1 R 20 gm' ;gm E IE 1 r 84Ω + R E gm E

Ð3 Ð2.5 Ð2 Ð1.5 Ð1 0.5 1 1.5 2 2.5 3 VIN (V) Ð10 In application circuits, the resistor RE between the E-output and ground is used to set the OTA transfer characteristic. The Ð20 input voltage is transferred with a voltage gain of 1V/V to the Ð30

E-output. According to the E-output impedance and the RE Ð40 resistor size, a certain current flows to ground. As mentioned Ð50 before this current is reflected by the current mirror to the Ð60 I 3 ¥ I high impedance collector output by a fixed ratio of three. C E Ð70 rE varies vs IQ Figure 2 and Figure 3 show the OTA transfer characteristic IQ = ±17mA Ω Ω for a RE = 33 and RE = 84 , which equal to voltage-to- current conversion factors (transconductance) of ±75mA/V Ω and ±25mA/V. The limitation for this transconductance FIGURE 3. OTA Transfer Characteristic, RE = 84 . adjustment is the maximum E-output current of ±25mA. The achievable transconductance and the corresponding mini- mum RE versus the input voltage shows Figure 4. The area 160 160 I = 25mA left to the R + r curve can be used and results in a E MAX E E 140 140 transconductance below the gm’ curve. The variation of rE vs 120 R + r 120 total quiescent current is shown in the typical performance E E (IC = ±37.5mA) ) 100 100 curve section. Ω

( RE + rE E 80 (IC = ±75mA) 80 + R E V 3•V r 60 60 ≈ • IN ≈ IN gm' (I = ±75mA) IC 3 ;RE ±rE C + 40 40 r E RE IC

20 20 Transconductance gm' (mA/V)

gm' (IC = ±37.5mA) 0 0 I (mA) 0 ±0.5 ±1 ±1.5 ±2 ±2.5 ±3 ±3.5 ±4 I Maximum Input Voltage (V) C 70

C IC 60 FIGURE 4. RE + rE Selection Curve. B 50 DISTORTION rE 40

E 30 The OPA2662’s harmonic distortion characteristics into a I E 50Ω load are shown vs frequency in the typical performance R 20 E I curves for a total quiescent current of ±17mA for both 33Ω E OTAs, which equals to ±8.5mA for each of them. The harmonic distortion performance is greatly affected by Ð1.25 Ð1 Ð0.75 Ð0.5 0.25 0.5 0.75 1 1.25 V (V) IN the applied quiescent current. In order to demonstrate this Ð10 behavior Figure 5 illustrates the harmonic distortion perfor- Ð20 mance vs frequency for a low quiescent current of ±8mA, Ð30 for a medium of ±17mA and for a high of ±34mA. It can be seen that the harmonic distortion decreases with all increas- Ð40 ing quiescent current. Ð50 The same effect is expressed in other ways by the OTA Ð60 I 3≈ ¥ I CIC 3 E• IE transfer characteristics for different IQs in the typical perfor- r varies vs I Ð70 ErE varies vsQ IQ mance curves. I = ±17mA± QIQ = 17mA

Ω FIGURE 2. OTA Transfer Characteristic, RE = 33 .

11 OPA2662 ± HARMONIC DISTORTION 200ns at full output power (IOUT = 75mA). This enable vs TOTAL QUIESCENT CURRENT feature allows multiplexing and demultiplexing, or a shut- Ð20 2nd, 8mA down mode, when the device is not in use. If the EN-input 3rd, 8mA is connected to ground or a digital “Low” is applied to it, the Ð30 collector (C) and emitter (E) pins are switched in the high- impedance mode. When the EN-input is connected to +5V 3rd, 17mA (+VCC) or a digital “High” is applied to it, the corresponding Ð40 OTA operates at the adjusted quiescent current. The initial 2nd, 17mA setting for the enable pins is that they are connected to the 2nd, 34mA positive supply as shown in Figure 6. Ð50 Harmonic Distortion (dBc) 3rd, 34mA THERMAL CONSIDERATIONS Ð60 The performance of the OPA2662 is dependent on the total 1.0M 3.0M 10M 30M 100M quiescent current which can be externally adjusted over a Frequency (Hz) wide range. As shown later, the distortion will reduce when FIGURE 5. Harmonic Distortion. setting the OTAs for higher quiescent current. For a reliable operation, some thermal considerations should be made. The BASIC CONNECTIONS total power dissipation consists of two separate terms: Shown in Figure 6 are the basic connections for the a) the quiescent power dissipation, P OPA2662’s standard operation. Most of these connections DQ are not shown in subsequent circuit diagrams for better =+ • + + • ± PDQ VCC IQ VCC IQ (1) clarification. Power supply bypass capacitors should be located as close as possible to the device pins. Solid tanta- b) the power dissipation in the output transistors, P lum capacitors are generally the better choice. For further DO details see the “Circuit Layout” section. = • PDO ()VOUT ±VCC IOUT (2)

ENABLE INPUTS Equations 1 and 2 can be used in conjunction with the Switching stages compatible to TTL logic levels are pro- OPA2662’s absolute maximum rating of the junction tem- vided for each OTA to switch the corresponding voltage- perature for a save operation. controlled current source on within 30ns, and off within θ TJ = TA + (PDQ + PDO) • JA (3)

+ 2.2µF 10nF 470pF

+5V 1 16 +VCCOUT +VCC 100Ω 50Ω 2 15 VIN1 E B1 1 RE1 OTA1 3 14 IOUT1 EN1 C1 Logic 4 13 NC GND PTAT Supply 5 12 NC I Adjust Q Logic

(1) I RQ EN 6 11 OUT2 2 OTA2 C2 100Ω 50Ω V 7 10 IN2 B 2 E2 RE2

Ð5V 8 9 ÐVCC OUT OPA2662 ÐVCC

Ω 2.2µF 10nF 470pF NOTE: (1) RQ = 750 set roughly, IQ = ±17mA. +

FIGURE 6. Basic Connections.

OPA2662 12 QUIESCENT CURRENT CONTROL CIRCUIT LAYOUT The quiescent current of the OPA2662 can be varied by The high-frequency performance of the power operational transconductance amplifier OPA2662 can be greatly af- connecting a user selectable external resistor, RQ, between pin fected by the physical layout of the printed circuit board. 5 and –VCC. The quiescent current affects the operating currents of both OTA sections simultaneously, controlling the The following tips are offered as suggestions, not as absolute bandwidth and the AC-behavior as well as the musts. Oscillations, ringing, poor bandwidth and settling, transconductance. The typical performance curves illustrate and peaking are all typical problems that plague high-speed components when they are used incorrectly. the relationship of the quiescent current versus the RQ and the transconductance, gM. The OPA2662 is specified at a typical • Bypass power supplies very close to the device pins. Use ± quiescent current of 17mA. This is set by a resistor RQ of tantalum chip capacitors (approximately 2.2µF); a paral- Ω ° 750 at 25 C ambient temperature. The useful range for the IQ is lel 470pF ceramic and a 10µF chip capacitor may be ± ± from 3mA to 65 mA (see Figure 7). The application circuits added if desired. Surface-mount types are recommended do not always show the resistor RQ, but it is required for proper because of their low lead inductance. operation. With a fixed resistor, the quiescent current in- • PC board traces for power lines should be wide to reduce creases with increasing temperature, keeping the impedance or inductance. transconductance and AC-behavior constant. Figure 7 shows the internal current source circuitry. A resistor with a value of • Make short, low-inductance traces. The entire physical Ω circuit should be as small as possible. 150 is used to limit the current if pin 5 is shorted to –VCC. This resistor has a relative accuracy of ±25% which causes an • Use a low-impedance ground plane on the component increasing deviation from the typical RQ vs IQ curve at decreas- side to ensure that low-impedance ground is available ing RQ values. throughout the layout. • Do not extend the ground plane under high-impedance nodes sensitive to stray capacitances such as the amplifier’s input terminals. • Sockets are not recommended because they add signifi- OPA2662 cant inductance and parasitic capacitance. If sockets must be used, consider using zero-profile solderless sockets. • Use low-inductance, surface-mounted components. Cir- cuits using all surface-mount components with the

50kΩ OPA2662 will offer the best AC performance. • A resistor (100Ω to 250Ω) in series with the high- 150Ω impedance inputs is recommended to reduce peaking. ±25% • Plug-in prototype boards and wire-wrap boards will not function well. A clean layout using RF techniques is 58 essential—there are no shortcuts. RQ

ÐVCC • Some applications may require a limitation for the maximum output current to flow. This can be achieved by TOTAL QUIESCENT CURRENT vs R Q adding a resistor (about 10Ω) between supply lines 1 and 70 16, and, 8 and 9 (see also Figure 8). The tradeoff of this 60 technique is a reduced output voltage swing. This is due (±mA)

Q to the voltage drop across the resistors caused by both the 50 Typical collector and the emitter currents. 40

10 Total Quiescent Current, I

0 10 100 1k 10k Ω RQ - Resistor Value ( )

FIGURE 7. Quiescent Current Setting.

13 OPA2662 +5V

Rt1 TTL1

150Ω Ω R1 100 100Ω 2 B1 Rc1 14 Rb1 OTA1 C1 R2 Ω 15 100 0Ω Rp1 10Ω R (1) C (1) 51Ω C2 C1 16 E1

Re1 Pos +5V 1 R (1) C (1) e2 e1 C C 1 2 C (1) 2.2µF 10nF 3

GND 4

C C 4 5 C (1) +5V 2.2µF 10nF 6 Rt2 TTL2 R Neg Ð5V 8 3 R 100Ω Ω n1 150 10Ω Rb2 7 9 B2 RC3 11 100Ω C2 R OTA2 4 10 0Ω 100Ω 750Ω (1) (1) RC4 CC2 Re3 5 Ω 51 RQ E2

R (1) C (1) e4 e2 NOTE: (1) Not assembled.

FIGURE 8. Evaluation Circuit Schematic.

Silk Screen Component Side Solder Side

FIGURE 9. Evaluation Circuit Silkscreen and Board Layouts.

OPA2662 14 TYPICAL APPLICATIONS

VOUT

14 11 VOUT 100Ω 2 7 VIN OPA2662 50Ω 50Ω

15 10 100Ω 150Ω

FIGURE 10. Single Ended-to-Differential Line Driver.

R Q 5 OPA2662 I ÐVCC OUT 14 100Ω 2 VIN1 RB1 15 EN1 3

4 11 50Ω 100Ω V IN2 7 R EN2 B2 6 10 R Q 5 ÐVCC 14 50Ω 100Ω V IN3 2 RB3

EN3 3 15

4 11 50Ω 150Ω 150Ω 150Ω 100Ω 7 VIN4 R B4 6 EN4 10 12 13 14 150Ω Y Y Y Y OPA2662 16 3 2 1 0 4 Ω LE 50 8 74HC237 5 CS2

CS1 A2 A1 A0 5

FIGURE 11. Current Distribution Multiplexer.

15 OPA2662 +5V Application Specific

+VCC +VCCOUT +VCC +VCCOUT 2N3906 116 1 16 RQ I = ±13mA Ω 5 OUT 75 VOUT = ±1V RQ C1 I C I IBIAS ÐVCC Q 1 OUT1 14 IBIAS EN 5 14 1 ÐVCC R 3 OPA602 B1 75Ω 100Ω B1 VIN1 I Ω 2 2 OUT2 100 15 VIN1 15 E1 E 4 75Ω V = ±1V GND 1 OUT C 4 2 LASER DIODE C2 11 R 11 B2 75Ω V 100Ω V IN2 B2 IN2 7 100Ω 7 E2 EN V = ±1V 1 E E EN 2 EN2 10 3 6 VE = ±1V 10 OPA2662 Ω Ω EN2 OPA2662 Ð5V 8 9 225 225 6 8 9 ÐVCC ÐVCCOUT 50Ω 50Ω ÐVCC ÐVCCOUT

FIGURE 12. Laser Diode Driver. FIGURE 13. Two-Channel Current Output Driver.

5 RQ IQ 33pF ÐV C1 CC 3 EN1 14 RB1 B1 47Ω 2 100Ω 68Ω 75Ω 4 E1 V 15 OUT1 VIN 33pF C2 75Ω 11 RB2 B2 47Ω 7 100Ω 68Ω 75Ω E2 VOUT2 10 EN2 6 OPA2662 75Ω

FIGURE 14. Direct Feedback Buffer and 1 to 2 Demultiplexer.

OPA2662 16 +VCC +VCCOUT Voltage compliance across the load: 8Vp-p 1 16 R Q 5 C1 ÐVCC IQ 14 R B1 2 IOUT = ±75mA B Ω 1 100 E1 Q 3 EN1 15 ±1V GND 39Ω Data Equalization 4 R 6 OG Q EN 10 2 Playback R B2 E2 7 Amplifier B 100Ω 2 C2 Record/Play TTL 11 Selection OPA2662 8 9

ÐVCC ÐVCCOUT FIGURE 15. Analog-to-Digital Video Tape Record Amplifier.

+80V

75 430Ω

BFQ262 10

14 t EN1 100Ω 2

1 100Ω 10 7

11 EN 2 6 t OPA2662 1.5kΩ 200Ω 10pF

Ð5V FIGURE 16. Cascode Stage Driver.

Ω C 50 VOUT

100Ω 50Ω V IN B Ω 50 E 1/2

OPA2662 RE CE 100Ω 6.8pF

The precise pulse response and the high slew rate enables the OPA2662 to be used in digital communication systems. Figure 16 shows the output amplifier for a high-speed data transmission system up to 440Mbit/s. The current source output drives directly a 50Ω coax cable and guarantees a 1V voltage drop over the termination resistor at the end of the cable. The input

voltage to output voltage conversion factor is set by RE. CE compensates the stray capacitance at the collector output. The generator rise and fall time equals to 1.19ns and the OPA2662 slightly increases the rise and fall time to 1.26ns.

FIGURE 17. Driver Amplifier for a Digital 440Mbit/s Transmission System.

17 OPA2662 600 Output 400

200

Voltage (mV) Ð200 I = ±17mA Q Input R = 100Ω Ð400 E CE = 6.8pF Ω RC = 50 Ð600 0246810 Time (ns)

FIGURE 18. Pulse Response of the 400Mbit/s Line Driver.

OPA2662 VOUT /VIN 50Ω C1 14

Coax 50Ω B 50Ω 1 2

E1 Ω 15 100 Coax 6.8pF 100Ω C2 11 50Ω VOUT /VIN 50Ω 7 B2 50Ω

100Ω 3 EN1

6 EN2 E2 10

100Ω 6.8pF T/R Control

FIGURE 19. Bidirectional Line Driver.

+80V; 60mA tR = 2.4ns tF = 2.15ns to CRT 50Vp-p tR = 0.7ns OPA2662 1 9 t = 0.7ns CR3425 F 11 14 12pF 50Ω 0.46Vp-p 150Ω 7

150Ω 10 2 15

10nF 10Ω 50Ω

220Ω 220Ω 20pF 100pF

FIGURE 20. CRT Output Stage Driver for a 1600 x 1200 High-Resolution Graphic Monitor.

OPA2662 18 IMPORTANT NOTICE

Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability.

TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements.

Customers are responsible for their applications using TI components.

In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards.

TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI’s publication of information regarding any third party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.