OP
OPA2662
A26
62
OP
A26
62
Dual, Wide Bandwidth
OPERATIONAL TRANSCONDUCTANCE AMPLIFIER
FEATURES
DESCRIPTION
● 370MHz BANDWIDTH
● 58mA/ns SLEW RATE
The OPA2662 is a versatile driver device for ultra
wide-bandwidth systems, including high-resolution
video, RF and IF circuitry, communications and test
equipment. The OPA2662 includes two power voltage-controlled current sources, or operational
transconductance amplifiers (OTAs), in a 16-pin DIP
or SOL-16 package and is specified for the extended
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
delivers up to ±75mA output current.
● HIGH OUTPUT CURRENT: ±75mA
● 400Mbit/s DATA RATE
● VOLTAGE-CONTROLLED CURRENT
SOURCE
● ENABLE/DISABLE FUNCTION
APPLICATIONS
● HEAD DRIVE AMPLIFIER FOR ANALOG/
DIGITAL VIDEO TAPES AND DATA RECORDERS
● LED AND LASER DIODE DRIVER
● HIGH CURRENT VIDEO BUFFER OR LINE
DRIVER
● RF OUTPUT STAGE DRIVER
● HIGH DENSITY DISK DRIVES
The transconductance of both OTAs can be adjusted
between pin 5 and –VCC by an external resistor,
allowing bandwidth, quiescent current, harmonic distortion and gain trade-offs to be optimized. The output current can be set with a degeneration resistor
between the emitter and GND. The current mirror
ratio between the collector and emitter currents is
fixed to three. Switching stages compatible to logic
TTL levels make it possible to turn each OTA separately on within 30ns and off within 200ns at full
power.
+VCCOUT
(16)
I (mA)
80
70
IC
60
50
40
30
B
E
C
(10,15)
(11,14)
20
IE
+1
(2,7)
–1
EN
–0.8 –0.6 –0.4
0.2
0.4
0.6
0.8
1 VIN (V)
–10
–20
(3, 6)
–30
–40
–50
–60
(9)
–VCCOUT
–70
–80
1/2 OPA2662
OTA Transfer
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
1991 Burr-Brown Corporation
PDS-1129D
Printed in U.S.A. August, 1994
SPECIFICATIONS
ELECTRICAL
DC-SPECIFICATIONS
At VCC = ±5V, RQ = 750Ω, TA = +25°C, and configured as noted under “CONDITIONS”.
OPA2662AP, AU
PARAMETER
CONDITIONS
OTA INPUT OFFSET VOLTAGE
Initial
vs Temperature
vs Supply (tracking)
vs Supply (non-tracking)
vs Supply (non-tracking)
Matching
OTA B-INPUT BIAS CURRENT
Initial
vs Temperature
vs Supply (tracking)
vs Supply (non-tracking)
vs Supply (non-tracking)
Matching
OTA C-OUTPUT BIAS CURRENT
Initial
vs Temperature
vs Supply (tracking)
vs Supply (non-tracking)
vs Supply (non-tracking)
Matching
B-INPUT IMPEDANCE
Impedance
OTA INPUT NOISE
Input Noise Voltage Density
Output Noise Current Density
Signal-to-Noise Ratio
OTA C-RATED OUTPUT
Output Voltage Compliance
Output Current
Output Impedance, rC
OTA E-RATED OUTPUT
Voltage Output
DC Current Output
Voltage Gain
Output Impedance, rE
POWER SUPPLY
Rated Voltage
Derated Performance
Positive Quiescent Current
for both OTAs(4)
Positive Quiescent Current
for both OTAs(4)
Quiescent Current Range
TEMPERATURE RANGE
Specification
Thermal Resistance, θJA
AP
AU
MIN
RE = 50kΩ, RC = 40Ω
VCC = ±4.5V to ±5.5V, RE = 50kΩ, RC = 1kΩ
VCC = +4.5V to +5.5V, RE = 50kΩ, RC = 1kΩ
VCC = –4.5V to –5.5V, RE = 50kΩ, RC = 1kΩ
RE = 100Ω, RC = 40Ω
VCC = ±4.5V to ±5.5V, RE = 50kΩ, RC = 1kΩ
VCC = +4.5V to +5.5V, RE = 50kΩ, RC = 1kΩ
VCC = –4.5V to –5.5V, RE = 50kΩ, RC = 1kΩ
TYP
MAX
UNITS
12
35
27
15
40
2
±30
mV
µV/°C
dB
dB
dB
mV
1
–5
60
160
40
0.2
–1/+5
0.5
1.5
72
236
92
0.06
–0.5/+1.5
±7
±1
µA
nA/°C
nA/V
nA/V
nA/V
µA
RE = 100Ω, RC = 1kΩ
VCC = ±4.5V to ±5.5V
VCC = +4.5V to +5.5V
VCC = –4.5V to –5.5V
±0.5
mA
µA/°C
µA/V
µA/V
µA/V
mA
IQ = ±17mA
4.5 || 1.5
MΩ || pF
f = 20kHz to 100MHz
4.4
0.09
97
nV/√Hz
nA/√Hz
dB
±3.4
±75
V
mA
4.5 || 6.5
kΩ || pF
±3.0
V
±25
mA
0.86
0.98
16 || 2.2
V/V
V/V
Ω || pF
S/N = 20 log • (0.7/VN • √5MHz)
IC = ±5mA, RE = 100Ω, RC = 1kΩ
RC = 40Ω, RE = 100Ω
VIN = ±3V
IQ = ±17mA
RE = 100Ω, RC = 40Ω
RE = 100Ω, RC = 40Ω
VIN = ±4V
VIN = ±2.5V
RE = 100Ω
RE = 50kΩ
IQ = ±17mA
RE = 50kΩ, RC = 1kΩ
RE = 50kΩ, RC = 40Ω
RQ = 750Ω, RE = 50kΩ, RC = 1kΩ,
Both Channels Enabled
RQ = 750Ω, RE = 50kΩ, RC = 1kΩ,
Both Channels Disabled
Programmable
RQ = 3kΩ to 30Ω
±4.5
±3
+15
±3
±65
mA
Ambient Temperature
–40
+85
°C
+17
±5.5
±6
+18
+4
90
100
VDC
VDC
mA
mA
°C/W
°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
Typical at VCC = ±5VDC, R Q = 750Ω, IC = ±37.5mA (VIN = 2.5Vpp, RE = 100Ω), IC = ±75mA (VIN = 2.5Vpp, RE = 50Ω), RSOURCE = 50Ω, and TA = +25°C, unless
otherwise noted.
OPA2662AP, AU
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
FREQUENCY DOMAIN
LARGE SIGNAL BANDWIDTH
IC = ±37.5mA
IC = ±75mA
IC = ±37.5mA (Optimized)
IC = ±75mA (Optimized)
GROUP DELAY TIME
Measured Input to Output
(Demo Board Used)
HARMONIC DISTORTION
Second Harmonic
Third Harmonic
Second Harmonic
Third Harmonic
Second Harmonic
Third Harmonic
Second Harmonic
Third Harmonic
Second Harmonic
Third Harmonic
Second Harmonic
Third Harmonic
CROSSTALK
FEEDTHROUGH
Off Isolation
TIME DOMAIN
Rise Time
Slew Rate
RE = 100Ω, RC = 50Ω
RE = 100Ω, RC = 25Ω
RE = 100Ω, RC = 50Ω, CE = 5.6pF
RE = 100Ω, RC = 25Ω, CE = 5.6pF
150
200
370
250
MHz
MHz
MHz
MHz
RE = 100Ω, RC = 50Ω
B to E
B to C
1.2
2.5
ns
ns
–31
–37
–33
–32
–29
–32
–30
–25
–31
–30
–28
–23
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
Typical Curve Number 3
IC = ±37.5mA, f = 30MHz
IC = ±75mA, f = 30MHz
–51
–56
dB
dB
RE = 100Ω, f = 30MHz
RE = 50Ω, f = 30MHz
–90
–90
dB
dB
10% to 90%
75mA Step IC
150mA Step IC
IC = 75mA
IC = 150mA
2
2.6
37.5
58
ns
ns
mA/ns
mA/ns
f = 10MHz, IC = ±37.5mA
f = 10MHz, IC = ±75mA
f = 30MHz, IC = ±37.5mA
f = 30MHz, IC = ±75mA
f = 50MHz, IC = ±37.5mA
f = 50MHz, IC = ±75mA
CHANNEL SELECTION
OPA2662AP, AU
PARAMETER
ENABLE INPUTS
Logic 1 Voltage
Logic 0 Voltage
Logic 1 Current
Logic 0 Current
SWITCHING CHARACTERISTICS
EN to Channel ON Time
EN to Channel OFF Time
Switching Transient, Positive
Switching Transient, Negative
CONDITIONS
MIN
2
0
0.8
–1
VSEL = 2.0V to 5V
VSEL = 0V to 0.8V
IC = 150mAp-p, f = 5MHz
90% Point of VO = 1Vp-p
10% Point of VO = 1Vp-p
(Measured While Switching
Between the Grounded Channels)
3
TYP
1.1
0.05
MAX
UNITS
VCC + 0.6
0.8
10
V
V
µA
µA
30
200
30
–80
ns
ns
mV
mV
OPA2662
SPECIFICATIONS
(CONT)
ELECTRICAL (Full Temperature Range –40°C to +85°C)
At VCC = ±5VDC, RQ = 750Ω, TA = TMIN to T MAX, unless otherwise noted, and configured as noted under “CONDITIONS”.
OPA2662AP, AU
PARAMETER
CONDITIONS
OTA INPUT OFFSET VOLTAGE
Initial
Matching
RE = 50kΩ, RC = 40Ω
OTA INPUT BIAS CURRENT
Initial
Matching
RE = 100Ω, RC = 40Ω
MIN
–1.9
–1.2
OTA TRANSCONDUCTANCE
Transconductance
OTA C-RATED OUTPUT
Output Voltage Compliance
POWER SUPPLY
Positive Quiescent Current for both OTAs(4)
IC = 75mA, RE = 0
580
IC = ±5mA, RE = 100Ω, RC = 16Ω
±3.2
RQ = 750Ω, RE = 50kΩ, RC = 1kΩ,
Both Channels Selected
+8
Top View
+VCC
1
16 +VCCOUT
B1
2
15 E1
EN1
3
GND
4
OTA1
PTAT
Supply
5
7
–VCC
8
±36
±7.2
mV
mV
1
0.2
5.9
1.2
µA
µA
610
mA/V
V
+17
+25
mA
NOTE: (1) Inputs are internally diode-clamped to ±VCC.
PACKAGE/ORDERING INFORMATION
13 NC
12 NC
PRODUCT
Logic
B2
12
2
14 C1
Logic
6
UNITS
Power Supply Voltage ........................................................................ ±6V
Input Voltage(1) .................................................................. ±VCC to ±0.7V
Operating Temperature ................................................... –40°C to +85°C
Storage Temperature ..................................................... –40°C to +125°C
Junction Temperature .................................................................... +175°C
Lead Temperature (soldering, 10s) ............................................... +300°C
Digital Input Voltages (EN1, EN2) ............................... –0.5 to +VCC +0.7V
SOL-16/DIP
EN2
MAX
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
IQ Adjust
TYP
OTA2
OPA2662AP
OPA2662AU
11 C2
9
–VCCOUT
ELECTROSTATIC
DISCHARGE SENSITIVITY
Any integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with appropriate 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
TEMPERATURE
RANGE
16-Pin Plastic DIP
SOL-16 Surface Mount
180
211
–40°C to +85°C
–40°C to +85°C
NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix C of Burr-Brown IC Data Book.
10 E2
OPA2662
PACKAGE
PACKAGE
DRAWING
NUMBER(1)
4
TYPICAL PERFORMANCE CURVES
At VCC = ±5V, RQ = 750Ω, and TA = +25°C, unless otherwise specified.
OTA B TO E-INPUT OFFSET VOLTAGE
vs TEMPERATURE
OTA B-INPUT RESISTANCE
vs TOTAL QUIESCENT CURRENT
15
18
OTA B-Input Resistance (MΩ)
Input Offset Voltage (mV)
14
13
12
11
10
RE = 50kΩ
RC = 40Ω
9
8
–50
16
14
12
10
8
6
4
2
0
–25
0
25
50
75
100
7
12
Temperature (°C)
17
22
27
32
37
42
47
Total Quiescent Current, IQ (±mA)
OTA B-INPUT BIAS CURRENT vs TEMPERATURE
OTA C-OUTPUT BIAS CURRENT vs TEMPERAURE
0.70
1.5
B-Input Bias Current (µA)
Output Bias Current (mA)
0.65
0.60
0.55
0.50
0.45
0.40
1.3
1.1
0.9
0.35
0.30
–50
–25
0
25
50
75
0.7
–50
100
0
25
50
75
Temperature (C°)
OTA E-OUTPUT RESISTANCE
vs TOTAL QUIESCENT CURRENT
OTA C-OUTPUT RESISTANCE
vs TOTAL QUIESCENT CURRENT
100
9
OTA C-Output Resistance, rC (kΩ)
50
OTA E-Output Resistance rE (Ω)
–25
Temperature (°C)
45
40
35
30
25
20
15
10
5
8
7
6
5
4
3
2
1
0
0
7
12
17
22
27
32
37
42
7
47
Total Quiescent Current, IQ (±mA)
12
17
22
27
32
37
Total Quiescent Current, IQ (±mA)
5
OPA2662
42
47
TYPICAL PERFORMANCE CURVES
(CONT)
At VCC = ±5V, RQ = 750Ω, and TA = +25°C, unless otherwise specified.
QUIESCENT CURRENT CHANGE vs TEMPERATURE
24
60
22
50
Quiescent Current (mA)
Total Quiescent Current, IQ (±mA)
TOTAL QUIESCENT CURRENT vs RQ
70
Typical
40
30
20
20
18
16
14
12
10
10
0
10
100
1k
–60
10k
–40
–20
OTA C-Output Current (mA)
80
RE = 33Ω
40
RE = 50Ω
0
RE = 100Ω
–40
RC = 10Ω
VIN = 1.9Vp-p
–80
60
80
100
75
50
25
0
–25
–50
–75
RE = 33Ω, RC = 11Ω
–100
–120
–0.95
0
–25 –20 –15 –10
0.95
–5
0
5
80
OTA C-Output Current (mA)
600
IQ = 65mA
500
IQ = 34mA
400
IQ = 17mA
IQ = 8mA
100
–100
–50
0
50
100
150
30
IQ = ±34mA
IQ = ±65mA
40
20
0
IQ = ±17mA IQ = ±8mA
–20
–40
–60
–100
–200
200
RE = 0Ω
–100
0
Input Voltage (mV)
Input Voltage (mV)
OPA2662
25
60
–80
–150
20
100
700
0
–200
15
OTA TRANSFER CHARACTERISTICS
vs TOTAL QUIESCENT CURRENT
TRANSCONDUCTANCE vs VIN vs IQ
300
10
OTA E-Output Current (mA)
Input Voltage (V)
200
40
100
RE = 25Ω
OTA C-Output Current (mA)
20
IC/IE TRANSFER CURVE
OTA TRANSFER CHARACTERISTICS vs RE
120
OTA Transconductance gm (mA/V)
0
Temperature (°C)
RQ - Resistor Value (Ω)
6
100
200
TYPICAL PERFORMANCE CURVES
(CONT)
At VCC = ±5V, RQ = 750Ω, IC = ±37.5mA (RE = 100Ω, VIN = 2.5Vp-p), IC = ±75mA (RE = 50Ω, VIN = 2.5Vp-p), and T AMB = +25°C, unless otherwise noted.
BANDWIDTH vs OUTPUT CURRENT
OPEN-LOOP GAIN vs FREQUENCY
5
80
IQ = ±17mA
IC = ±75mA
RC = 15Ω
RE = 25Ω
–5
IQ = ±8mA
60
IC = ±37.5mA
RC = 30Ω
RE = 50Ω
Gain (dB)
Gain (dB)
0
–10
IQ = ±34mA
40
Test Circuit
50Ω
DUT
100Ω
BUF601
180Ω
20
–15
50Ω
+1
50Ω
–20
1M
10M
100M
0
100k
1G
300k
1M
Frequency (Hz)
OTA LARGE SIGNAL PULSE RESPONSE
vs OUTPUT CURRENT
30M
100M
OTA C-Output Current (mA)
100
ICMAX = ±37mA
RE = 100Ω
1.0
ICMAX = ±75mA
RE = 50Ω
0
–1.0
IQ = ±17mA
tRISE = tFALL = 1ns (Generator)
–2.0
0
50
100
150
50
IQ = ±34mA
0
IQ = ±8mA
IQ = ±17mA
–5
RC = 10Ω, RE = 50Ω
–100
200
10
0
20
Time (ns)
30
40
50
Time (ns)
OPTIMIZED FREQUENCY RESPONSE
vs OUTPUT VOLTAGE
OTA LARGE SIGNAL PULSE RESPONSE
vs OUTPUT VOLTAGE
20
1.0
RC = 10Ω
6Vp-p
0
0.5
RC = 30Ω
Gain (dBm)
OTA C-Output Voltage (V)
10M
OTA LARGE SIGNAL PULSE RESPONSE
vs TOTAL QUIESCENT CURRENT
2.0
OTA C-Output Voltage (V)
3M
Frequency (Hz)
0
VIN = 2.7Vp-p
100Ω
–0.5
Test Circuit
RC
3Vp-p
0.6Vp-p
–20
Test Circuit
VIN
–40
100Ω
RE
50Ω
50Ω
–1.0
0
50
100Ω
VOUT
VOUT
12Ω
1.4Vp-p
100
150
–60
0.1M
200
Time (ns)
50Ω
6.8pF
CE
1M
IQ = ±17mA
10M
100M
Frequency (Hz)
7
OPA2662
1G
TYPICAL PERFORMANCE CURVES
(CONT)
VCC = ±5V, RQ = 750Ω, IC = ±37.5mA (RE = 100Ω, VIN = 2.5Vp-p), IC = ±75mA (RE = 50Ω, VIN = 2.5Vp-p), and TA = +25°C, unless otherwise specified.
tOFF
Worst Case
EN-TIME
SWITCHING TRANSIENT
2
0
0
–2
–4
–75
4
200
2
150
0
100
Output Voltage (mV)
75
EN Voltage (V)
EN Voltage (V)
4
OTA C-Output Current (mA)
250
50
0
–50
–100
Both Inputs
Connected
with 150Ω
to GND
fIN = 5MHz
0
250
tON
500
Time (ns)
20
0
0
VIN
–20
Off Isolation (dB)
Crosstalk (dB)
VIN
1
–40
2
3
EN1
–60
C1
CURVE EN1 EN2
1
1
1
2
1
0
EN2
3
0
1
–80
1M
IC1 = 150mAp-p
100Ω
VIN
50Ω
B1
OTA1
E1
B2
10M
50Ω
OTA2
–60
–80
E2
OPA2662
–40
VOUT
C2
100Ω
–20
50Ω
50Ω
100M
–100
300k
1G
HARMONIC DISTORTION vs FREQUENCY
10M
100M
1G
OTA TRANSFER CHARACTERISTICS
–20
80
–25
OTA C-Output Current (mA)
Harmonic Distortion (dBc)
1M
Frequency (Hz)
Frequency (Hz)
2nd Harmonic
–30
3rd Harmonic
–35
–40
IQ = ±17mA
RE = 100Ω
RC = 50Ω
IC = 75mAp-p
–45
–50
1.0M
Time (ns)
OFF ISOLATION vs FREQUENCY
CROSSTALK vs FREQUENCY
20
–100
300k
–150
500
250
0
3.0M
10M
30M
40
20
IQ = ±34mA
IQ = ±65mA
IQ = ±8mA
0
IQ = ±17mA
–20
–40
–60
–80
–VIN
100M
Frequency (Hz)
OPA2662
60
0
Variable Input Voltage (mV)
for ±75mA Collector Current at the End Points
8
+VIN
TYPICAL PERFORMANCE CURVES (CONT)
At VCC = ±5V, RQ = 750Ω, (RE = 100Ω, VIN = 2.5Vp-p), IC = ±75mA (RE = 50Ω, VIN = 2.5Vp-p), and TA = +25°C, unless otherwise specified.
44
Test Circuit
DUT
+
–144
V
150Ω
14
IQ = ±17mA
N
–
50Ω
–154
4.4
IQ = ±34mA
–164
100
1k
124
140
–134
44
–144
10k
4.4
–154
150Ω
IQ = ±8mA
VN
1.4
1M
100k
IQ = ±17mA
IQ = ±8mA
1.4
–164
100
10k
Frequency (Hz)
1k
Frequency (Hz)
100k
1M
BUFFER OUTPUT GAIN ERROR, B to E
BUFFER TRANSFER FUNCTION, B to E
50
4
RE = 100Ω
IQ = ±17mA
3
–40°C
45
40
2
Gain Error (%)
Buffer Output Voltage (V)
14
IQ = ±34mA
1
0
–1
35
30
85°C
25
20
15
–2
10
–3
5
0
–4
–5
–4
–3
–2
–1
0
1
2
3
4
–5
5
–4
–3
–2
–1
0
1
2
3
4
5
Input Voltage (V)
Input Voltage (V)
OTA E-OUTPUT SMALL SIGNAL PULSE RESPONSE
OTA E-OUTPUT LARGE SIGNAL PULSE RESPONSE
150
4
Output Voltage (V)
Output Voltage (mV)
100
50
0
–50
2
0
–2
–100
IQ = ±17mA, tRISE = tFALL = 1ns (Generator), RE = 100Ω
IQ = ±17mA, tRISE = tFALL = 1ns (Generator), RE = 100Ω
–150
–4
0
20
40
60
80
100
0
120
Time (ns)
20
40
60
80
100
Time (ns)
9
OPA2662
120
Buffer Noise (nV/√ Hz)
–134
OTA Noise (nV/√ Hz)
BUFFER SPECTRAL NOISE DENSITY
140
Buffer Noise (dBm/√ Hz)
OTA Noise (dBm/√ Hz)
OTA SPECTRAL NOISE DENSITY
–124
APPLICATION INFORMATION
too, is a voltage-controlled current source. The three OTA
terminals are labelled; base (B), emitter (E) and collector
(C), calling attention to its similarity to a transistor. The
OTA sections can be viewed as wide-band, voltage-controlled, bipolar current sources. The collector current of each
OTA is controlled by the differential voltage between the
high-impedance base and low-impedance emitter. If a current flows at the emitter, then the current mirror reflects this
current to the high-impedance collector by a fixed ratio of
three. Thus, the collector is determined by the product of the
base-emitter voltage times the transconductance times the
current mirror factor. The typical performance curves illustrate the OTA open-loop transfer characteristic. Due to the
PTAT (Proportional to Absolute Temperature) biasing, the
transconductance is constant vs temperature and can be
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 characteristic has one essential difference, as can be seen in the
performance curve: the (sense) of the C output current. This
current flows out of the C terminal for positive B-to-E input
voltage and into for negative.
The OPA2662 typically operates from ±5V power supplies
(±6V maximum). Do not attempt to operate with larger
power supply voltages or permanent damage may occur. All
inputs of the OPA2662 are protected by internal diode
clamps, as shown in the simplified schematic in Figure 1.
These protection diodes can safely, continuously conduct
10mA (30mA peak). The input signal current must be
limited if input voltages can exceed the power supply voltages by 0.7V, as can occur when power supplies are switched
off and a signal source is still present. The buffer outputs E1
and E2 are not current-limited or protected. If these outputs
are shorted to ground, high currents could flow. Momentary
shorts to ground (a few seconds) should be avoided, but are
unlikely to cause permanent damage.
DISCUSSION OF
PERFORMANCE
OTA
The two OTA sections of the OPA2662 are versatile driver
devices for wide-bandwidth systems. Applications best suited
to this new circuit technology are those where the output
signal is current rather than voltage. Such applications include driving LEDs, laser diodes, tuning coils, and driver
transformers. The OPA2662 is also an excellent choice to
drive the video heads of analog or digital video tape recorders in broadcast and HDTV-quality or video heads of highdensity data recorders.
The symbol for the OTA sections is similar to that of a
bipolar transistor. Application circuits for the OTA look and
operate much like transistor circuits—the bipolar transistor,
The OTAs offer many advantages over discrete transistors.
First of all, they are self-biased and bipolar. The output
current is zero-for-zero differential input voltage. AC inputs
centered at zero produce an output current that is bipolar and
centered at zero. The self-biased OTAs simplify the design
process and reduce the number of components. It is far more
linear than a transistor. The transconductance of a transistor
is proportional to its collector current. But since the collector
current is dependent upon the signal, it and the
transconductance are fundamentally nonlinear. Like transistor circuits, OTA circuits may also use emitter degeneration
+VCC
+VCCOUT
(1)
(16)
+VCCOUT
(16)
x1
x3
EN (3,6)
B
E
(2,7)
E (10,15)
B (2,7)
C
C (11,14)
Control
+1
(10,15)
IE
(11,14)
(4)
EN
3 x IE
Bias
Circuitry
(3,6)
OTA
(9)
–VCCOUT
x1
IQ Adjust
(5)
RQ (ext.)
(8)
–VCC
(9)
–VCCOUT
RQ = 750Ω sets IQ to ±17mA for both OTAs.
FIGURE 1. Simplified Block and Circuit Diagram.
OPA2662
10
x3
to reduce the effect that offset voltages and currents might
otherwise have on the DC operating point of the OTA. The
E degeneration resistor may be bypassed by a capacitor to
maintain high AC gain. Other cases may require a capacitor
with less value to optimize high-frequency performance.
The transconductance of the OTA with degeneration can be
calculated by:
1
1
gm + R E
I (mA)
70
50
rE
E
; gm = r1
E
40
IE
30
RE
84Ω
20
–3 –2.5 –2 –1.5 –1
In application circuits, the resistor RE between the E-output
and ground is used to set the OTA transfer characteristic. The
input voltage is transferred with a voltage gain of 1V/V to the
E-output. According to the E-output impedance and the RE
resistor size, a certain current flows to ground. As mentioned
before this current is reflected by the current mirror to the
high impedance collector output by a fixed ratio of three.
Figure 2 and Figure 3 show the OTA transfer characteristic
for a RE = 33Ω and RE = 84Ω, which equal to voltage-tocurrent conversion factors (transconductance) of ±75mA/V
and ±25mA/V. The limitation for this transconductance
adjustment is the maximum E-output current of ±25mA. The
achievable transconductance and the corresponding minimum RE versus the input voltage shows Figure 4. The area
left to the RE + rE curve can be used and results in a
transconductance below the gm’ curve. The variation of rE vs
total quiescent current is shown in the typical performance
curve section.
IC ≈ 3 •
IC
60
B
IE
0.5
–10
1
1.5
2
2.5
3 VIN (V)
–20
–30
–40
–50
–60
IC 3 • IE
rE varies vs IQ
IQ = ±17mA
–70
FIGURE 3. OTA Transfer Characteristic, RE = 84Ω.
160
160
IE MAX = 25mA
140
140
RE + rE
(IC = ±37.5mA)
rE + RE (Ω)
120
V IN
3 • V IN
; RE ≈
– rE
rE + RE
IC
100
120
RE + rE
(IC = ±75mA)
80
60
80
60
gm' (IC = ±75mA)
40
40
20
20
gm' (IC = ±37.5mA)
0
0
I (mA)
IC
100
±0.5
±1
±1.5
±2
±2.5
±3
±3.5
Transconductance gm' (mA/V)
gm' =
IC
C
0
±4
Maximum Input Voltage (V)
70
C
IC
60
B
FIGURE 4. RE + rE Selection Curve.
50
rE
E
IE
RE
33Ω
–1.25 –1 –0.75 –0.5
DISTORTION
The OPA2662’s harmonic distortion characteristics into a
50Ω load are shown vs frequency in the typical performance
curves for a total quiescent current of ±17mA for both
OTAs, which equals to ±8.5mA for each of them.
40
30
20
IE
0.25 0.5 0.75
–10
1
The harmonic distortion performance is greatly affected by
the applied quiescent current. In order to demonstrate this
behavior Figure 5 illustrates the harmonic distortion performance vs frequency for a low quiescent current of ±8mA,
for a medium of ±17mA and for a high of ±34mA. It can be
seen that the harmonic distortion decreases with all increasing quiescent current.
1.25 VIN (V)
–20
–30
–40
–50
–60
–70
The same effect is expressed in other ways by the OTA
transfer characteristics for different IQs in the typical performance curves.
ICIC 3≈ •3IE• IE
rErEvaries
vsvs
IQ IQ
varies
IQIQ= =±17mA
±17mA
FIGURE 2. OTA Transfer Characteristic, RE = 33Ω.
11
OPA2662
200ns at full output power (IOUT = ±75mA). This enable
feature allows multiplexing and demultiplexing, or a shutdown mode, when the device is not in use. If the EN-input
is connected to ground or a digital “Low” is applied to it, the
collector (C) and emitter (E) pins are switched in the highimpedance mode. When the EN-input is connected to +5V
(+VCC) or a digital “High” is applied to it, the corresponding
OTA operates at the adjusted quiescent current. The initial
setting for the enable pins is that they are connected to the
positive supply as shown in Figure 6.
HARMONIC DISTORTION
vs TOTAL QUIESCENT CURRENT
–20
Harmonic Distortion (dBc)
2nd, 8mA
3rd, 8mA
–30
3rd, 17mA
–40
2nd, 17mA
2nd, 34mA
–50
3rd, 34mA
–60
1.0M
3.0M
10M
30M
THERMAL CONSIDERATIONS
The performance of the OPA2662 is dependent on the total
quiescent current which can be externally adjusted over a
wide range. As shown later, the distortion will reduce when
setting the OTAs for higher quiescent current. For a reliable
operation, some thermal considerations should be made. The
total power dissipation consists of two separate terms:
100M
Frequency (Hz)
FIGURE 5. Harmonic Distortion.
BASIC CONNECTIONS
Shown in Figure 6 are the basic connections for the
OPA2662’s standard operation. Most of these connections
are not shown in subsequent circuit diagrams for better
clarification. Power supply bypass capacitors should be
located as close as possible to the device pins. Solid tantalum capacitors are generally the better choice. For further
details see the “Circuit Layout” section.
a) the quiescent power dissipation, PDQ
P DQ = +V CC • I Q+ + V CC • I Q–
(1)
b) the power dissipation in the output transistors, PDO
P DO = ( V OUT – V CC ) • I OUT
ENABLE INPUTS
Switching stages compatible to TTL logic levels are provided for each OTA to switch the corresponding voltagecontrolled current source on within 30ns, and off within
(2)
Equations 1 and 2 can be used in conjunction with the
OPA2662’s absolute maximum rating of the junction temperature for a save operation.
TJ = TA + (PDQ + PDO) • θJA
(3)
+
2.2µF
+5V
10nF
470pF
1
16
2
15
+VCCOUT
+VCC
100Ω
VIN1
B1
EN1
50Ω
3
E1
RE1
OTA1
14
IOUT1
C1
Logic
GND
IQ Adjust
RQ(1)
EN2
4
13
NC
12
NC
PTAT
Supply
5
Logic
6
11
OTA2
VIN2
–5V
50Ω
B2
7
10
8
9
OPA2662
–VCC
NOTE: (1) RQ = 750Ω set roughly, IQ = ±17mA.
+
2.2µF
FIGURE 6. Basic Connections.
OPA2662
IOUT2
C2
100Ω
12
10nF
470pF
E2
RE2
–VCC OUT
CIRCUIT LAYOUT
The high-frequency performance of the power operational
transconductance amplifier OPA2662 can be greatly affected by the physical layout of the printed circuit board.
The following tips are offered as suggestions, not as absolute
musts. Oscillations, ringing, poor bandwidth and settling,
and peaking are all typical problems that plague high-speed
components when they are used incorrectly.
QUIESCENT CURRENT CONTROL
The quiescent current of the OPA2662 can be varied by
connecting a user selectable external resistor, RQ, between pin
5 and –VCC. The quiescent current affects the operating currents of both OTA sections simultaneously, controlling the
bandwidth and the AC-behavior as well as the
transconductance. The typical performance curves illustrate
the relationship of the quiescent current versus the RQ and the
transconductance, gM. The OPA2662 is specified at a typical
quiescent current of ±17mA. This is set by a resistor RQ of
750Ω at 25°C ambient temperature. The useful range for the IQ is
from ±3mA to ±65 mA (see Figure 7). The application circuits
do not always show the resistor RQ, but it is required for proper
operation. With a fixed resistor, the quiescent current increases with increasing temperature, keeping the
transconductance and AC-behavior constant. Figure 7 shows
the internal current source circuitry. A resistor with a value of
150Ω is used to limit the current if pin 5 is shorted to –VCC.
This resistor has a relative accuracy of ±25% which causes an
increasing deviation from the typical RQ vs IQ curve at decreasing RQ values.
• Bypass power supplies very close to the device pins. Use
tantalum chip capacitors (approximately 2.2µF); a parallel 470pF ceramic and a 10µF chip capacitor may be
added if desired. Surface-mount types are recommended
because of their low lead inductance.
• PC board traces for power lines should be wide to reduce
impedance or inductance.
• Make short, low-inductance traces. The entire physical
circuit should be as small as possible.
• Use a low-impedance ground plane on the component
side to ensure that low-impedance ground is available
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 significant inductance and parasitic capacitance. If sockets must
be used, consider using zero-profile solderless sockets.
OPA2662
• Use low-inductance, surface-mounted components. Circuits using all surface-mount components with the
OPA2662 will offer the best AC performance.
50kΩ
• A resistor (100Ω to 250Ω) in series with the highimpedance inputs is recommended to reduce peaking.
150Ω
±25%
5
• Plug-in prototype boards and wire-wrap boards will not
function well. A clean layout using RF techniques is
essential—there are no shortcuts.
8
RQ
–VCC
• Some applications may require a limitation for the maximum output current to flow. This can be achieved by
adding a resistor (about 10Ω) between supply lines 1 and
16, and, 8 and 9 (see also Figure 8). The tradeoff of this
technique is a reduced output voltage swing. This is due
to the voltage drop across the resistors caused by both the
collector and the emitter currents.
TOTAL QUIESCENT CURRENT vs RQ
Total Quiescent Current, IQ (±mA)
70
60
50
Typical
40
30
20
10
0
10
100
1k
10k
RQ - Resistor Value (Ω)
FIGURE 7. Quiescent Current Setting.
13
OPA2662
+5V
TTL1
Rt1
150Ω
R1
100Ω
100Ω
B1
R2
Rb1
100Ω
2
15
Rc1
14
OTA1
C1
Rp1
10Ω
0Ω
RC2(1)
51Ω
CC1(1)
16
E1
Re1
Pos +5V
Re2(1)
Ce1(1)
1
C1
2.2µF
C2
10nF
C3(1)
GND
4
C4
2.2µF
+5V
Rt2
C5
10nF
C6(1)
TTL2
Neg –5V
R3
100Ω
Rb2
B2
100Ω
R4
100Ω
7
10
11
OTA2
9
RC3
C2
0Ω
RC4(1)
Re3
51Ω
8
Rn1
10Ω
150Ω
750Ω
CC2(1)
5
RQ
E2
Re4(1)
Ce2(1)
NOTE: (1) Not assembled.
FIGURE 8. Evaluation Circuit Schematic.
Silk Screen
Component Side
FIGURE 9. Evaluation Circuit Silkscreen and Board Layouts.
OPA2662
14
Solder Side
TYPICAL APPLICATIONS
VOUT
11
14
100Ω
VIN
2
VOUT
7
OPA2662
50Ω
50Ω
10
15
100Ω
150Ω
FIGURE 10. Single Ended-to-Differential Line Driver.
RQ
–VCC
5 OPA2662
IOUT
14
100Ω
VIN1
2
RB1
15
EN1 3
4
11
50Ω
100Ω
VIN2
EN2
RB2
RQ
–VCC
7
10
6
5
14
50Ω
100Ω
VIN3
RB3
2
15
EN3 3
11
4
150Ω
150Ω
150Ω
100Ω
VIN4
50Ω
7
RB4 6
12
16
Y3
13
Y2
150Ω
14
Y1
Y0
LE
74HC237
8
CS2
CS1
A2
A1
4
10
EN4
OPA2662
50Ω
5
A0
5
FIGURE 11. Current Distribution Multiplexer.
15
OPA2662
+5V
Application
Specific
+VCC +VCCOUT
+VCC +VCCOUT
2N3906
1
RQ
–VCC
RQ
IQ
C1
5
14
100Ω B
1
VIN1
1
16
IOUT1
IBIAS
–VCC
EN1
IBIAS
OPA602
IOUT2
100Ω
IOUT = ±13mA 75Ω
75Ω
15
E1
C2
11
RB2
VIN2
100Ω
7
75Ω
7
E2
EN1
E2
3
EN2 OPA2662
6
8
9
EN2
10
10
6 OPA2662
8
9 225Ω
–5V
VOUT = ±1V
75Ω
LASER DIODE
VIN2 100Ω B
2
VOUT = ±1V
2
4
C2
11
EN
C1
RB1 3
15
E1
GND
4
5
14
VIN1
2
16
VE = ±1V
VE = ±1V
225Ω
–VCC –VCCOUT
50Ω
–VCC –VCCOUT
50Ω
FIGURE 13. Two-Channel Current Output Driver.
FIGURE 12. Laser Diode Driver.
RQ
–VCC
EN1
5
IQ
3
RB1
100Ω
C1
14
B1
47Ω
2
4
33pF
68Ω
E1
75Ω
VOUT1
15
VIN
C2
RB2
100Ω
33pF
75Ω
11
B2
47Ω
7
68Ω
E2
EN2
VOUT2
10
6 OPA2662
75Ω
FIGURE 14. Direct Feedback Buffer and 1 to 2 Demultiplexer.
OPA2662
75Ω
16
+VCC +VCCOUT
1
RQ
–VCC
RB1
Q
C1
14
IOUT = ±75mA
E1
15
39Ω
ROG
4
6
EN2
Equalization
Q
RB2
10
Playback
Amplifier
E2
7
B2
100Ω
TTL
5
IQ
3 EN1
GND
±1V
Data
16
2
B1
100Ω
Voltage compliance
across the load: 8Vp-p
C2
Record/Play
Selection
OPA2662
8
9
11
–VCC –VCCOUT
FIGURE 15. Analog-to-Digital Video Tape Record Amplifier.
+80V
430Ω
BFQ262
75
10
t
14
EN1
100Ω
2
15
1
100Ω
10
7
11
EN2
6 OPA2662
t
1.5kΩ
200Ω
10pF
–5V
FIGURE 16. Cascode Stage Driver.
C
50Ω
VOUT
100Ω
VIN
50Ω
B
50Ω
E
1/2
OPA2662
RE
100Ω
CE
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
Voltage (mV)
400
200
0
–200
IQ = ±17mA
RE = 100Ω
CE = 6.8pF
RC = 50Ω
–400
–600
0
2
Input
4
6
8
10
Time (ns)
FIGURE 18. Pulse Response of the 400Mbit/s Line Driver.
OPA2662
VOUT /VIN
50Ω
C1
14
Coax
50Ω
50Ω
B1
2
E1
100Ω
15
6.8pF
Coax
100Ω
C2
11
7
100Ω
VOUT /VIN
50Ω
50Ω
B2
50Ω
3 EN1
E2
6 EN2
10
100Ω
6.8pF
T/R
Control
FIGURE 19. Bidirectional Line Driver.
tR = 2.4ns
tF = 2.15ns
+80V; 60mA
to CRT
tR = 0.7ns
tF = 0.7ns
50Ω
1
OPA2662
14
11
0.46Vp-p
150Ω
150Ω
CR3425
50Vp-p
9
12pF
7
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
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