TI THS4302RGTR

THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
WIDEBAND FIXED-GAIN AMPLIFIER
FEATURES
APPLICATIONS
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fixed-Gain Closed-Loop Amplifier
Multiple Gain Options
– THS4302: 5 V/V (14 dB)
Wide Bandwidth: 2.4 GHz
High Slew Rate: 5500 V/µs
Low Total Input Referred Noise: 2.8 nV/√Hz
Low Distortion
– HD3: -86 dBc at 30 MHz
– HD3: -81 dBc at 70 MHz
– IMD3: -88 dBc at 100 MHz
– OIP3: 39 dBm at 100 MHz
– IMD3: -73 dBc at 300 MHz
– OIP3: 32 dBm at 300 MHz
High Output Drive: ±180 mA
Power Supply Voltage: 3 V or 5 V
Wideband Signal Processing
Wireless Transceivers
IF Amplifier
ADC Preamplifier
DAC Output Buffers
Test, Measurement, and Instrumentation
Medical and Industrial Imaging
DESCRIPTION
The THS4302 device is a wideband, fixed-gain amplifier that offers high bandwidth, high slew rate, low
noise, and low distortion. This combination of specifications enables analog designers to transcend current performance limitations and process analog signals at much higher speeds than previously possible
with closed-loop, complementary amplifier designs.
This device is offered in a 16-pin leadless package
and incorporates a power-down mode for quiescent
power savings.
APPLICATION CIRCUIT
VS+
SMALL SIGNAL FREQUENCY RESPONSE
16
+
22 µF
47 pF
0.1 µF
14
30.1 Ω
12
Rf
Rg
50 Ω Source
_
+
VI
VO
THS4302
49.9 Ω
100 Ω
Small Signal Gain - dB
FB
10
8
6
4
2
VS-
VO = 200 mV
RL = 100 Ω
VS = 5 V
0
10 M
100 M
1G
10 G
f - Frequency - Hz
+
22 µF
FB
47 pF
0.1 µF
30.1 Ω
FB = Ferrite Bead
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.
PowerPAD is a trademark of Texas Instruments.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2002–2005, Texas Instruments Incorporated
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
ABSOLUTE MAXIMUM RATING
over operating free-air temperature range unless otherwise noted
(1)
UNIT
Supply voltage, VS
6V
Input voltage, VI
±VS
Output current, IO
200 mA
Continuous power dissipation
See Dissipation Rating Table
Maximum junction temperature, TJ
150°C
Maximum junction temperature, continuous operation, long term reliability, TJ (2)
125°C
Storage temperature range, Tstg
-65°C to 150°C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds
(1)
(2)
300°C
The absolute maximum temperature under any condition is limited by the constraints of the silicon process. Stresses above these
ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability.
These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not
implied.
The maximum junction temperature for continuous operation is limited by package constraints. Operation above this temperature may
result in reduced reliability and/or lifetime of the device.
RECOMMENDED OPERATING CONDITIONS
MIN
MAX
±1.5
±2.5
3
5
VS- +1
VS+ -1
Dual supply
Supply voltage, VCC (VS+ and VS-)
Single supply
Common-mode input voltage range
UNIT
V
V
PACKAGE DISSIPATION RATINGS
(1)
(2)
(3)
PACKAGE
ΘJC(°C/W)
ΘJA(°C/W) (1)
RGT (16) (3)
2.4
39.5
POWER RATING (2)
TA ≤ 25°C
TA = 25°C
3.16
1.65 W
This data was taken using the JEDEC standard High-K test PCB.
Power rating is determined with a junction temperature of 125°C. This is the point where distortion starts to substantially increase.
Thermal management of the final PCB should strive to keep the junction temperature at or below 125°C for best performance and long
term reliability.
The THS4302 device may incorporate a PowerPAD™ on the underside of the chip. This acts as a heatsink and must be connected to a
thermally dissipative plane for proper power dissipation. Failure to do so may result in exceeding the maximum junction temperature
which can permanently damage the device. See TI technical brief SLMA002 and SLMA004 for more information about utilizing the
PowerPAD thermally enhanced package.
AVAILABLE OPTIONS
INTERNAL FIXED GAIN
RESISTOR VALUES (+5)
(1)
2
PACKAGED DEVICES
RG
RF
THS4302RGTT
50 Ω
200 Ω
THS4302RGTR
The PowerPAD is electrically isolated from all other pins.
PACKAGE TYPE (1)
Leadless (RGT-16)
TRANSPORTATION MEDIA,
QUANTITY
Tape and Reel, 250
Tape and Reel, 3000
THS4302
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SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
PIN ASSIGNMENTS
NC
V IN−
16 15 14 13
12
2
11
3
10
Rg
1
Rf
VS−
V IN+
PD
RGT PACKAGE
TOP VIEW
4
5
6
7
8
VS+
9
VOUT
NC = No connect
ELECTRICAL CHARACTERISTICS
THS4302 (Gain = +5 V/V) Specifications: VS = 5 V, RL = 100 Ω, (unless otherwise noted)
TYP
PARAMETER
TEST CONDITIONS
OVERTEMPERATURE
UNITS
MIN/
TYP/
MAX
2.4
GHz
Typ
12
GHz
Typ
25°C
25°C
0°C to
70°C
-40°C
to 85°C
AC PERFORMANCE
Small signal bandwidth
G = +5, VO = 200 mVRMS
Gain bandwidth product
Full-power bandwidth
G = +5, VO = 2 Vpp
875
MHz
Typ
Slew rate
G = +5, VO = 2 V Step
5500
V/µs
Min
RL = 100 Ω
-66
dBc
RL = 1 kΩ
-75
dBc
RL = 100 Ω
-81
dBc
RL = 1 kΩ
-85
dBc
fc = 100 MHz
-88
dBc
Harmonic distortion
Second harmonic distortion
G = +5, VO = 1 VPP,
f = 70 MHz
Third harmonic distortion
Typ
Typ
Third order intermoduation (IMD3)
VO = 1 VPP envelope, 200 kHz tone
spacing
fc = 300 MHz
-73
dBc
Third order output intercept (OIP3)
VO = 1 VPP, 200 kHz fc = 100 MHz
tone spacing
fc = 300 MHz
39
dBm
32
dBm
Total input referred noise
f = 1 MHz
2.8
nV/√Hz
Typ
16
dB
Typ
Noise figure
Typ
Typ
DC PERFORMANCE
Voltage gain
VI = ±50 mV, VCM = 2.5 V
Input offset voltage
VCM = 2.5 V
Average offset voltage drift
Input bias current
Average bias current drift
5
4.95
4.95
4.95
V/V
Min
5
5.05
5.05
5.05
V/V
Max
2
4.25
5.25
5.25
mV
Max
±20
±20
µV/°C
Typ
13
15
µA
Max
±55
±55
nA/°C
Typ
VCM = 2.5 V
VCM = 2.5 V
VCM = 2.5 V
7
10
3
THS4302
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SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
ELECTRICAL CHARACTERISTICS (continued)
THS4302 (Gain = +5 V/V) Specifications: VS = 5 V, RL = 100 Ω, (unless otherwise noted)
TYP
PARAMETER
TEST CONDITIONS
25°C
OVERTEMPERATURE
25°C
0°C to
70°C
-40°C
to 85°C
UNITS
MIN/
TYP/
MAX
INPUT CHARACTERISTICS
Common-mode input range
0.5/4.5
1/4
1.1/3.9
1.2/3.8
V
Min
Common-mode rejection ratio
VCM = 2 V to 3 V
60
52
50
50
dB
Min
Input resistance
Noninverting input
1.6
MΩ
Typ
Input capacitance
Noninverting input
1
pF
Max
OUTPUT CHARACTERISTICS
Output voltage swing
1/4
1.1/3.9
1.2/3.8
1.2/3.8
V
Min
Output current (sourcing)
RL = 5 Ω
180
170
165
160
mA
Min
Output current (sinking)
RL = 5 Ω
180
170
165
160
mA
Min
Output impedance
f = 10 MHz
0.2
Ω
Typ
POWER SUPPLY
Operating voltage
5
5.5
5.5
5.5
V
Max
Maximum quiescent current
37
42
46
48
mA
Max
Minimum quiescent current
37
32
29
26
mA
Min
Power supply rejection ratio (PSRR +)
VS+ = 5 V to 4.5 V, VS- = 0 V
60
54
52
51
dB
Min
Power supply rejection ratio (PSRR -)
VS+ = 5 V, VS- = 0 V to 0.5 V
75
65
64
62
dB
Min
PD = 0 V
0.8
1.0
1.1
1.2
mA
Max
1.1
1.5
V
Min
1.1
0.9
POWER-DOWN CHARACTERISTICS
Maximum power-down current
Power-on voltage threshold
Power-down voltage threshold
V
Max
Turnon time delay, td(on)
50% of final value
6
µs
Typ
Turnoff time delay, td(off)
50% of final value
5
µs
Typ
100
kΩ
Typ
250
Ω
Typ
Input impedance
Output impedance
4
f = 100 kHz
THS4302
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SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
TYPICAL CHARACTERISTICS
Table of Graphs (5 V)
FIGURE
S-Parameter vs Frequency
1
Small signal frequency response
2
Large signal frequency response
3
Slew rate vs Output voltage
4
Harmonic distortion vs Frequency
5, 6, 7, 8
Harmonic distortion vs Output voltage swing
9
Second-order intermodulation distortion vs Frequency
10
Second-order intercept point vs Frequency
11
Third order intermodulation distortion vs Frequency
12
Third-order intercept point vs Frequency
13
Voltage and current noise vs Frequency
Settling time
14
15, 16
Quiescent current vs Supply voltage
17
Output voltage vs Load resistance
18
Capacitive load frequency response
19
Gain vs Case temperature
20
Rejection ratios vs Frequency
21
Rejection ratios vs Case temperature
22
Common-mode rejection ratio vs Input common-mode range
23
Input offset voltage vs Case temperature
24
Positive input bias current vs Case temperature
25
Small signal transient response
26
Large signal transient response
27
Overdrive recovery
28
Closed-loop output impedance vs Frequency
29
Power-down quiescent current vs Supply voltage
30
Power-down output impedance vs Frequency
31
Turnon and turnoff delay times
32
Power-down S-Parameter vs Frequency
33
Table of Graphs (3 V)
FIGURE
Small signal frequency response
34
Large signal frequency response
35
Slew rate vs Output voltage
36
Output voltage vs Load resistance
37
Capacitive load frequency response
38
Gain vs Case temperature
39
S - Parameter vs Frequency
40
Input offset voltage vs Case temperature
41
Positive input bias current vs Case temperature
42
Overdrive recovery
43
5
THS4302
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SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
Typical Test Data
S-Parameter (Measured using standard THS4302EVM, edge number 6443548, with VS = 5 V in a 50-Ω test system)
Frequency MHz
6
S11 (dB)
S11 (Ang)
S21 (dB)
S21 (Ang)
S12 (dB)
S12 (Ang)
S22 (dB)
1
-55.86328
-3.728516
14.10889
-0.093384
-96.26953
20.78809
-70.32422
S22 (Ang)
122.5
2
-55.75781
-4.832764
14.11621
-0.109863
-98.18359
-120.6758
-65.65234
97.16016
10
-53.0293
-29.01563
14.11035
-0.350189
-78.10156
121.2148
-52.01953
73.91406
50
-42.92383
-82.44141
14.16309
-1.682312
-61.82813
75
-45.27539
142.0391
100
-37.35156
-97.42188
14.34766
-4.422119
-56.37891
61.26367
-31.04981
115.4414
150
-35.64258
-105.9063
14.38428
-7.657471
-54.44336
53.0957
-26.75098
98.26172
200
-33.27344
-111.1133
14.42041
-10.49512
-53.72852
34.22656
-25.3418
85.07031
250
-32.18945
-114.2891
14.39209
-13.63135
-53.55273
31.70508
-24.14844
77.09766
300
-30.92578
-114.4297
14.40918
-17.17871
-53.94727
21.56934
-23.53613
72.94531
350
-30.29492
-113.9727
14.38477
-19.34375
-54.23828
19.45508
-22.99512
70.63281
400
-29.11816
-113.5313
14.38184
-23.08594
-55.13281
16.29395
-22.13379
72.0625
450
-28.44141
-116
14.35645
-25.62305
-56.33594
14.38232
-21.45215
71.90234
500
-27.50977
-114.082
14.36035
-28.69922
-58.48828
12.0708
-20.56641
74.21094
550
-26.51856
-112.25
14.3208
-32.48047
-63.26367
3.492187
-19.71094
74.85938
600
-26.01856
-113.6719
14.30713
-34.17773
-67.62109
27.33594
-19.2959
75.58984
700
-24.03613
-115.8984
14.23242
-39.5918
-68.02734
172.2422
-17.80078
77.79297
800
-21.97559
-117.4922
14.1665
-47.05664
-55.4082
171.0703
-15.81494
77.22266
900
-20.40137
-120.7305
14.11133
-51.92969
-50.38477
168.8125
-14.38965
76.04297
1000
-18.70313
-123.4023
14.06006
-57.80078
-46.64453
163.1016
-12.91406
73.89063
1250
-15.14893
-134.7031
13.93872
-75.02344
-40.19141
152.5313
-9.994141
65.77734
1500
-12.66602
-149.0625
13.74683
-88.4375
-35.73438
139.7109
-7.968018
55.74414
1750
-11.48975
-168.9922
12.97827
-110.2852
-31.94531
112.5
-6.750977
40.24414
2000
-11.68311
-169.8203
12.18066
-123.043
-34.46094
84.83984
-7.211182
31.3877
THS4302
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SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
TYPICAL THS4302 CHARACTERISTICS (5 V)
S-PARAMETER
vs
FREQUENCY
10
−20
50 Ω
50 Ω
−40
S11
−60
S12
−70
16
14
14
S22
−30
−50
16
12
10
8
6
RL = 100 Ω
VO = 200 mV
VS = 5 V
4
−80
2
−90
1M
10 M
100 M
1G
f − Frequency − Hz
10 G
10 M
0
100 k
10 G
100 M
1G
HARMONIC DISTORTION
vs
FREQUENCY
2000
−70
HD2
−80
−90
HD3
0.5
1
1.5
2
−110
2.5
−70
−80
HD2
−90
HD3
−100
−100
0
RL = 1 kΩ
VO = 1 VPP
VS = 5 V
−60
Harmonic Distortion − dBc
Rise
3000
10 G
−50
RL = 100 Ω
VO = 1 VPP
VS = 5 V
−60
Fall
−110
1
VO − Output Voltage − VPP
10
f − Frequency − MHz
10
1
100
100
f − Frequency − MHz
Figure 4.
Figure 5.
Figure 6.
HARMONIC DISTORTION
vs
FREQUENCY
HARMONIC DISTORTION
vs
FREQUENCY
HARMONIC DISTORTION
vs
OUTPUT VOLTAGE SWING
−50
−50
−50
Harmonic Distortion − dBc
RL = 100 Ω
VO = 2 VPP
VS = 5 V
−60
−65
−70
HD2
−80
RL = 1 kΩ
VO = 2 VPP
VS = 5 V
−60
−70
HD3
−80
HD2
−90
HD2, f = 64 MHz
−60
−65
−70
HD3, f = 64 MHz
−75
HD2, f = 4 MHz
−80
−85
−90
−95
−100
−90
10
RL = 100 Ω
VS = 5 V
−55
HD3
1
10 M
f − Frequency − Hz
HARMONIC DISTORTION
vs
FREQUENCY
4000
−85
1M
SLEW RATE
vs
OUTPUT VOLTAGE
Harmonic Distortion − dBc
SR − Slew Rate − V/ µ s
1G
Figure 3.
5000
−75
RL = 100 Ω
VO = 2 V
VS = 5 V
Figure 2.
1000
Harmonic Distortion − dBc
100 M
−50
−55
6
Figure 1.
RL = 100 Ω
VS = 5 V
0
8
f − Frequency − Hz
7000
6000
10
2
0
−100
12
4
Harmonic Distortion − dBc
S−Parameter − dB
50 Ω
Source
VS = 5 V
LARGE SIGNAL FREQUENCY
RESPONSE
Large Signal Gain − dB
−
+
−10
50 Ω
Small Signal Gain − dB
0
SMALL SIGNAL FREQUENCY
RESPONSE
100
HD3, f = 4 MHz
−100
1
f − Frequency − MHz
10
f − Frequency − MHz
Figure 7.
Figure 8.
100
0
0.5
1
1.5
2
2.5
VO − Output Voltage Swing − VPP
Figure 9.
7
THS4302
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SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
TYPICAL THS4302 CHARACTERISTICS (5 V) (continued)
SECOND-ORDER
INTERMODULATION DISTORTION
vs
FREQUENCY
SECOND-ORDER
OUTPUT INTERCEPT POINT
vs
FREQUENCY
100
−55
95
−60
90
−65
85
−70
F2 + F1
−80
−85
−95
75
70
50
300
+2.5V
100
VO = 1 VPP
Envelope
31
Tone Spacing = 200 kHz
To 50-Ω Load, Add 3dB to
Refer To Amplifier Output
0
100
200
Hz
35
RL = 100 Ω
VS = 5 V
I n − Current Noise − pA/
37
10
10
In
Vn
1
400
100
500
f − Frequency − MHz
2.25
Falling Edge
1k
10 k
100 k
f − Frequency − Hz
1
10 M
1M
1.75
0.2
0
0.2
0.4
0.6
0.8
t − Time − ns
SETTLING TIME
QUIESCENT CURRENT
vs
SUPPLY VOLTAGE
OUTPUT VOLTAGE
vs
LOAD RESISTANCE
50
40
3
RL = 100 Ω
f= 1 MHz
VS = 5 V
2.75
2.5
2.25
2
1.75
Falling Edge
4
TA = 25°C
35
TA = −40°C
30
25
20
15
10
0
0.2 0.4
0.6 0.8
1
t − Time − ns
Figure 16.
1.2
1.4 1.6
3.5
3
VS = 5 V
TA = −40 to 85°C
2.5
2
1.5
1
0.5
5
1.25
1.2
4.5
TA = 85°C
VO − Output Voltage − V
3.5
3.25
1
5
45
Quiescent Current − mA
VO − Output Voltage − V
2.5
Figure 15.
Rising Edge
0
RL = 100 Ω
f= 1 MHz
VS = 5 V
2.75
Figure 14.
1.5
8
3
Figure 13.
4
1
0.2
SETTLING TIME
2
300
3.75
1000
Rising Edge
Hz
49.9
−2.5V
100
f − Frequency − MHz
3.25
100
Vn − Voltage Noise − nV/
50 Test
Equipment
10
Figure 12.
49.9
39
27
300
VOLTAGE AND CURRENT NOISE
vs
FREQUENCY
49.9
29
100
150
200
250
f − Frequency − MHz
THIRD-ORDER
OUTPUT INTERCEPT POINT
vs
FREQUENCY
50 Source
33
50
Figure 11.
41
VO = 0.5 VPP
Envelope
−100
0
Test data
measurement
point
−80
−95
F2 + F1
Figure 10.
43
VO = 1 VPP
Envelope
−75
−90
F2 − F1
55
100
150
200
250
f − Frequency − MHz
VO = 2 VPP
Envelope
−70
−85
50
0
OIP 3 − dBm
Tone Spacing = 200 kHz
To 50-Ω Load, Add 3dB to
Refer To Amplifier Output
60
−100
25
−65
80
65
VS = 5 V
RL = 100 Ω
VO = 1 VPP Envelope
Tone Spacing = 200 kHz
−90
−60
49.9
−2.5V
RL = 100 Ω
VS = 5 V
200 kHz Tone Spacing
−55
50 Test
Equipment
VO − Output Voltage − V
−75
49.9
49.9
OIP 2 − dBm
IMD 2 − dBc
F2 − F1
−50
Test data
measurement
point
+2.5V
50 Source
IMD 3 − dBc
−50
THIRD-ORDER
INTERMODULATION DISTORTION
vs
FREQUENCY
0
2.5
3
VS − Supply Voltage − V
10
100
RL − Load Resistance − Ω
Figure 17.
Figure 18.
3.5
4
4.5
5
1
1000
THS4302
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SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
TYPICAL THS4302 CHARACTERISTICS (5 V) (continued)
GAIN
vs
CASE TEMPERATURE
CAPACITIVE LOAD
FREQUENCY RESPONSE
14.02
1
R(ISO) = 24.9 Ω,
CL = 10 pF
Rejection Ratios − dB
VS = 5 V
R(ISO) = 8 Ω,
CL = 100 pF
−1
−1.5
R(ISO) = 12.1 Ω,
CL = 47 pF
13.98
13.96
50
CMRR
40
30
20
13.94
10
VS = 5 V
VS = 5 V
13.92
−40−30−20−10 0 10 20 30 40 50 60 70 80 90
−3
10 M
100 M
1G
0
100 k
1M
10 M
100 M
f − Frequency − Hz
Case Temperature − °C
Figure 19.
Figure 20.
Figure 21.
REJECTION RATIOS
vs
CASE TEMPERATURE
COMMON-MODE REJECTION RATIO
vs
INPUT COMMON-MODE RANGE
INPUT OFFSET VOLTAGE
vs
CASE TEMPERATURE
80
PSRR−
75
70
65
CMMR
60
55
PSRR+
50
45
VS = 5 V
40
−40−30−20−10 0 10 20 30 40 50 60 70 80 90
Case Temperature − °C
CMRR − Common-Mode Rejection Ratio − dB
f − Frequency − Hz
VS = 5 V
60
50
40
30
20
10
VS = 5 V
0
−10
0
1
2
3
4
5
4
3
2
1
0
−40−30−20−10 0 10 20 30 40 50 60 70 80 90
5
VICR − Input Common-Mode Voltage Range − V
Case Temperature − °C
Figure 22.
Figure 23.
Figure 24.
POSITIVE INPUT BIAS CURRENT
vs
CASE TEMPERATURE
SMALL SIGNAL TRANSIENT
RESPONSE
LARGE SIGNAL TRANSIENT
RESPONSE
2.65
4
10
2.6
3.5
8
2.55
6
2.5
4
2.45
2
2.4
12
1G
6
70
VOS − Input Offset Voltage − mV
−2
PSRR+
60
−0.5
−2.5
VS = 5 V
0
−40−30−20−10 0 10 20 30 40 50 60 70 80 90
Case Temperature − °C
Figure 25.
2.35
RL = 100 Ω
Input tr/tf = 60 ps
VS = 5 V
VO − Output Voltage − V
Rejection Ratios − dB
70
14
0
Gain −dB
Normalized Gain − dB
0.5
I IB+ − Positive Input Bias Current − µ A
REJECTION RATIOS
vs
FREQUENCY
3
2.5
2
RL = 100 Ω
Input tr/tf = 60 ps
VS = 5 V
1.5
0
2
4
6
8
10 12 14 16 18 20
Figure 26.
1
0
2
4
6
8 10 12 14 16 18 20
t − Time − ns
Figure 27.
9
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
TYPICAL THS4302 CHARACTERISTICS (5 V) (continued)
OVERDRIVE RECOVERY
100
3
1200
VS = 5 V
5
2.75
4
3.5
3
2.5
2.5
2
1.5
2.25
1
Output Impedance − Ω
4.5
VI − Input Voltage − V
10
1
0.5
0
2
−0.5
10 M
800
TA = −40°C
700
600
500
400
300
200
100
0
2.5 2.75 3 3.25 3.5 3.75 4 4.25 4.5 4.75 5
10 G
VS − Supply Voltage − V
POWER-DOWN OUTPUT
IMPEDANCE
vs
FREQUENCY
TURNON AND TURNOFF TIMES
DELAY TIME
POWER-DOWN S-PARAMETER
vs
FREQUENCY
80
3
70
2
60
100
VS = 5 V
1
50
0
40
−1
30
−2
−3
20
RL = 100 Ω
VS = 5 V
10
−4
−5
0
−6
−10
1M
10 M
100 M
Figure 31.
1G
−15
0
15
30
45
t − Time − µs
Figure 32.
60
75
V I − Input Voltage Level − V
Figure 30.
I O − Output Current Level − mA
Power-Down Output Impedance − Ω
TA = 25°C
900
Figure 29.
f − Frequency − Hz
10
100 M
1G
f − Frequency − Hz
TA = 85°C
1000
Figure 28.
1000
10
100 k
1100
0.1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
t − Time − µs
10
VS = 5 V and 3 V
0
Powerdown S−Parameter − dB
Single-Ended Output Voltage − V
Power-Down Quiescent Current − µ A
5.5
POWER-DOWN QUIESCENT
CURRENT
vs
SUPPLY VOLTAGE
OUTPUT IMPEDANCE
vs
FREQUENCY
−10
RG
S22
RF
C
−20
−
+
−30 50 Ω
−40 Source
50 Ω
50 Ω
50 Ω
S11
−50
−60
−70
S12
−80
−90
−100
1M
10 M
100 M
1G
f − Frequency − Hz
Figure 33.
10 G
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
TYPICAL THS4302 CHARACTERISTICS (3 V)
16
16
4000
14
14
3500
10
8
6
RL = 100 Ω
VO = 100 mV
VS = 3 V
4
12
10
8
6
RL = 100 Ω
VO = 0.5 V
VS = 3 V
4
2
0
3000
1M
10 M
100 M
1G
10 G
1500
1000
1M
14
Gain − dB
Normalized Gain − dB
10
100
RL − Load Resistance − Ω
VS = 3 V
14.02
−0.5
R(ISO) = 8 Ω,
CL = 100 pF
−1
−1.5
13.94
RL = 100 Ω,
VS = 5 V
10 M
1000
13.98
13.96
R(ISO) = 12.1 Ω,
CL = 47 pF
−2
−3
0.75
1.5
0
−2.5
100 M
1G
13.92
−40−30−20−10 0 10 20 30 40 50 60 70 80 90
Case Temperature − °C
f − Frequency − Hz
Figure 37.
Figure 38.
Figure 39.
S-PARAMETER
vs
FREQUENCY
INPUT OFFSET VOLTAGE
vs
CASE TEMPERATURE
POSITIVE INPUT BIAS CURRENT
vs
CASE TEMPERATURE
C
3.5
50 Ω
50 Ω
VOS − Input Offset Voltage − mV
−
+
S22
50 Ω
−40
S11
−60
S12
−70
−80
−90
−100
10 M
12
4
VS = 3 V
RF
0
100 M
1G
f − Frequency − Hz
Figure 40.
10 G
3
VS = 3 V
2.5
2
1.5
1
0.5
0
−40−30−20−10 0 10 20 30 40 50 60 70 80 90
I IB+ − Positive Input Bias Current − µ A
10
1M
0.5
0.75
1
1.25
VO − Output Voltage − V
14.04
R(ISO) = 24.9 Ω,
CL = 10 pF
0.5
1
−50
0.25
GAIN
vs
CASE TEMPERATURE
1.25
−30
0
CAPACITIVE LOAD
FREQUENCY RESPONSE
1.5
50 Ω
Source
10 G
OUTPUT VOLTAGE
vs
LOAD RESISTANCE
1
−10
1G
Figure 36.
1.75
−20
10 M
100 M
f − Frequency − Hz
Figure 35.
VS = 3 V
TA = −40 to 85°C
RG
RL = 100 Ω
VS = 3 V
500
Figure 34.
2.25
1
Rise
2000
0
100 k
f − Frequency − Hz
2
Fall
2500
0
100 k
VO − Output Voltage − V
SR − Slew Rate − V/ µ s
12
2
S−Parameter − dB
SLEW RATE
vs
OUTPUT VOLTAGE
LARGE SIGNAL
FREQUENCY RESPONSE
Large Signal Gain − dB
Small Signal Gain − dB
SMALL SIGNAL
FREQUENCY RESPONSE
10
8
VS = 3 V
6
4
2
0
−40−30−20−10 0 10 20 30 40 50 60 70 80 90
Case Temperature − °C
Case Temperature − °C
Figure 41.
Figure 42.
11
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
TYPICAL THS4302 CHARACTERISTICS (3 V) (continued)
OVERDRIVE RECOVERY
3
1.75
VO − Output Voltage − V
2.5
1.625
2.25
2
1.75
1.5
1.5
1.25
1
1.375
0.75
VS = 3 V
0.5
0.25
1.25
0
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
t − Time − µs
Figure 43.
12
VI − Input Voltage − V
2.75
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
APPLICATION INFORMATION
High-Speed Operational amplifiers
The THS4302 fixed-gain operational amplifier set new
performance levels, combining low distortion, high
slew rates, low noise, and a gain bandwidth in excess
of 2 GHz. To achieve the full performance of the
amplifier, careful attention must be paid to
printed-circuit board layout and component selection.
In addition, the devices provide a power-down mode
with the ability to save power when the amplifier is
inactive.
Applications Section Contents
• Wideband, Noninverting Operation
• Single Supply Operation
• Saving Power With Power-Down Functionality
• Driving an ADC With the THS4302
• Driving Capacitive Loads
• Power Supply Decoupling Techniques and
Recommendations
• Board Layout
• Printed-Circuit Board Layout Techniques for
Optimal Performance
• PowerPAD Design Considerations
• PowerPAD PCB Layout Considerations
• Thermal Analysis
• Design Tools
• Evaluation Fixtures and Application Support
Information
• Additional Reference Material
• Mechanical Package Drawings
generator. The 50-Ω series resistor at the VO terminal
in addition to the 50-Ω load impedance of the test
equipment, provides a 100-Ω load. The total 100-Ω
load at the output, combined with the 250-Ω total
feedback network load, presents the THS4302 with
an effective output load of 71 Ω for the circuit of
Figure 44.
INTERNAL FIXED RESISTOR VALUES
DEVICE
GAIN (V/V)
Rf
Rg
THS4302
+5
200
50
VS+
+
FB
22 µF
0.1 µF
47 pF
30.1 Ω
Rf
Rg
50-Ω Source
_
+
VI
VO
THS4302
49.9 Ω
100 Ω
VS−
+
22 µF
FB
47 pF
0.1 µF
30.1 Ω
FB = Ferrite Bead
Figure 44. Wideband, Noninverting
Gain Configuration
WIDEBAND, NONINVERTING OPERATION
SINGLE SUPPLY OPERATION
The THS4302 is a fixed-gain voltage feedback operational amplifier, with power-down capability,
designed to operate from a single 3-V to 5-V power
supply.
The THS4302 is designed to operate from a single
3-V to 5-V power supply. When operating from a
single power supply, care must be taken to ensure
the input signal and amplifier are biased appropriately
to allow for the maximum output voltage swing. The
circuits shown in Figure 45 demonstrate methods to
configure an amplifier in a manner conducive for
single supply operation.
Figure 44 is the noninverting gain configuration used
to demonstrate the typical performance curves. Most
of the curves were characterized using signal sources
with 50-Ω source impedance, and with measurement
equipment presenting a 50-Ω load impedance. In
Figure 44, the 49.9-Ω shunt resistor at the VIN
terminal matches the source impedance of the test
13
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
VS+
+
FB
22 µF
47 pF
0.1 µF
30.1 Ω
Rf
Rg
50-Ω Source
*2.5 V
VI
APPLICATION CIRCUITS
_
+
VO
THS4302
The time delays associated with turning the device on
and off are specified as the time it takes for the
amplifier to reach 50% of the nominal quiescent
current. The time delays are on the order of
microseconds because the amplifier moves in and out
of the linear mode of operation in these transitions.
100 Ω
49.9 Ω
*2.5 V
FB = Ferrite Bead
* = Low Impedance
Figure 45. DC-Coupled Single Supply Operation
Saving Power With Power-Down Functionality
The THS4302 features a power-down pin (PD) which
lowers the quiescent current from 37 mA down to
800 µA, ideal for reducing system power.
The power-down pin of the amplifier defaults to the
positive supply voltage in the absence of an applied
voltage, putting the amplifier in the power-on mode of
operation. To turn off the amplifier in an effort to
conserve power, the power-down pin can be driven
towards the negative rail. The threshold voltages for
power-on and power-down are relative to the supply
rails and given in the specification tables. Above the
Enable Threshold Voltage, the device is on. Below
the Disable Threshold Voltage, the device is off.
Behavior in between these threshold voltages is not
specified.
Note that this power-down functionality is just that;
the amplifier consumes less power in power-down
mode. The power-down mode is not intended to
provide a high-impedance output. In other words, the
power-down functionality is not intended to allow use
as a 3-state bus driver. When in power-down mode,
the impedance looking back into the output of the
amplifier is dominated by the feedback and gain
setting resistors, but the output impedance of the
device itself varies depending on the voltage applied
to the outputs.
Driving an Analog-to-Digital Converter With the
THS4302
The THS4302 amplifier can be used to drive highperformance analog-to-digital converters. Two
example circuits are presented below.
The first circuit uses a wideband transformer to
convert a single-ended input signal into a differential
signal. The amplified signal from the output of the
THS4302 is fed through a low-pass filter, via an
isolation resistor and an ac-coupling capacitor, to the
transformer.
For applications without signal content at dc, this
method of driving ADCs is useful. Where dc information content is required, the THS4500 family of
fully differential amplifiers may be applicable.
VS+
+
FB
22 µF
0.1 µF
47 pF
30.1 Ω
Rf
Rg
50-Ω Source
_
+
*2.5 V
VI
THS4302
49.9 Ω
*2.5 V
RISO 0.1 µF
24.9 Ω
IN
16.5 Ω
FB = Ferrite Bead
* = Low Impedance
ADS5422
14-Bit, 63 Msps
IN CM
24.9 Ω
Figure 46. Driving an ADC Via a Transformer
The second circuit depicts single-ended ADC drive.
While not recommended for optimum performance
using converters with differential inputs, satisfactory
performance can sometimes be achieved with singleended input drive. An example circuit is shown here
for reference.
14
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
VS+
+
FB
22 µF
0.1 µF
47 pF
30.1 Ω
The criterion for setting this R(ISO) resistor is a
maximum bandwidth, flat frequency response at the
load.
Rf
Rg
50-Ω Source
_
+
*2.5 V
VI
1
THS4302
Normalized Gain - dB
*2.5 V
RISO
16.5 Ω
0.1 µF
68 pf
IN
ADS807
12-Bit,
CM 53 Msps
IN
1.82 kΩ
R(ISO) = 24.9 Ω,
CL = 10 pF
0.5
49.9 Ω
FB = Ferrite Bead
* = Low Impedance
devices can easily cause this value to be exceeded.
Always consider this effect carefully, and add the
recommended series resistor as close as possible to
the THS4302 output pin (see Board Layout
Guidelines).
0.1 µF
0
-0.5
-1
R(ISO) = 8 Ω,
CL = 100 pF
-1.5
-2
-2.5
R(ISO) = 12.1 Ω,
CL = 47 pF
VS = 5 V
-3
10 M
100 M
1G
f - Frequency - Hz
Figure 48. Driving Capacitive Loads
#IMPLIED. For best performance, high-speed
ADCs should be driven differentially. See
the THS4500 family of devices for more
information.
Figure 47. Driving an ADC With a Single-Ended
Input
Driving Capacitive Loads
One of the most demanding, and yet very common,
load conditions for an op amp is capacitive loading.
Often, the capacitive load is the input of an A/D
converter, including additional external capacitance,
which may be recommended to improve A/D linearity.
High-speed amplifiers like the THS4302 can be
susceptible to decreased stability and closed-loop
response peaking when a capacitive load is placed
directly on the output pin. When the amplifier's
open-loop output resistance is considered, this
capacitive load introduces an additional pole in the
signal path that can decrease the phase margin.
When the primary considerations are frequency response flatness, pulse response fidelity, or distortion,
the simplest and most effective solution is to isolate
the capacitive load from the feedback loop by
inserting a series isolation resistor between the
amplifier output and the capacitive load.
The Typical Characteristics show the recommended
isolation resistor vs capacitive load and the resulting
frequency response at the load. Parasitic capacitive
loads greater than 2 pF can begin to degrade the
performance of the THS4302. Long PC board traces,
unmatched cables, and connections to multiple
Power Supply Decoupling
Recommendations
Techniques
and
Power supply decoupling is a critical aspect of any
high-performance amplifier design process. Careful
decoupling provides higher quality ac performance
(most notably improved distortion performance). The
following guidelines ensure the highest level of performance.
1. Place decoupling capacitors as close to the
power supply inputs as possible, with the goal of
minimizing the inductance of the path from
ground to the power supply. Inductance in series
with the bypass capacitors will degrade performance. Note that a narrow lead or trace has about
0.8 nH of inductance for every millimeter of
length. Each printed-circuit board (PCB) via also
has between 0.3 and 0.8 nH depending on length
and diameter. For these reasons, it is recommended to use a power supply trace about the
width of the package for each power supply lead
to the capacitors, and 3 or more vias to connect
the capacitors to the ground plane.
2. Placement priority should put the smallest valued
capacitors closest to the device.
3. Solid power planes can lead to PCB resonances
when they are not properly terminated to the
ground plane over the area and along the perimeter of the power plane by high frequency
capacitors. Doing so ensures that there are no
power plane resonances in the needed frequency
range. Values used are in the range of 2 pF - 50
pF, depending on the frequencies to be
suppressed, with numerous vias for each. Using
15
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
0402 or smaller component sizes is recommended. An approximate expression for the
resonant frequencies associated with a length of
one of the power plane dimensions is given in the
following equation. Note that a power plane of
arbitrary shape can have a number of resonant
frequencies. A power plane without distributed
capacitors and with active parts near the center
of the plane usually has n even (≥ 2) due to the
half wave resonant nature of the plane.
n (44 GHz mm)
frequency res where:
frequencyres = the approximate power plane resonant
frequencies in GHz
= the length of the power plane dimensions in
millimeters
n = an integer (n > 1) related to the mode of the oscillation
For guidance on capacitor spacing over the area
of the ground plane, specify the lowest resonant
frequency to be tolerated, then solve using the
equation above, with n = 2. Use this length for
the capacitor spacing. It is recommended that a
power plane, if used, be either small enough, or
decoupled as described, so that there are no
resonances in the frequency range of interest. An
alternative is to use a ferrite bead outside the
op-amp, high-frequency bypass capacitors to
decouple the amplifier, and mid- and
high-frequency bypass capacitors, from the
power plane. When a trace is used to deliver
power, its approximate self-resonance is given by
the equation above, substituting the trace length
for power plane dimension.
4. Bypass capacitors, because they have a
self-inductance, resonate with each other. To
achieve optimum transfer characteristics through
2 GHz, it is recommended that the bypass
arrangement employed in the prototype board be
used. The 30.1-Ω resistor in series with the
0.1-µF capacitor reduces the Q of the resonance
of the lumped parallel elements including the
0.1-µF and 47-pF capacitors, and the power
supply input of the amplifier. The ferrite bead
isolates the low-frequency 22-µF capacitor and
power plane from the remainder of the bypass
network.
5. By removing the 30.1-Ω resistor and ferrite bead,
the frequency response characteristic above 400
MHz may be modified. However, bandwidth, distortion, and transient response remain optimal.
6. Recommended values for power supply decoupling include a bulk decoupling capacitor (22 µF),
a ferrite bead with a high self-resonant frequency,
a mid-range decoupling capacitor (0.1 µF) in
series with a 30.1-Ω resistor, and a
high-frequency decoupling capacitor (47 pF).
16
BOARD LAYOUT
Printed-Circuit Board Layout Techniques
Optimal Performance
for
Achieving optimum performance with a high frequency amplifier like the THS4302 requires careful
attention to board layout parasitics and external
component types.
Recommendations that optimize performance include:
1. Minimize parasitic capacitance to any ac
ground for all of the signal I/O pins. However,
if using a transmission line at the I/O, then place
the matching resistor as close to the part as
possible. Except for when transmission lines are
used, parasitic capacitance on the output and the
noninverting input pins can react with the load
and source impedances to cause unintentional
band limiting. To reduce unwanted capacitance, a
window around the signal I/O pins should be
opened in all of the ground and power planes
around those pins. Otherwise, ground planes and
power planes (if used) should be unbroken elsewhere on the board, and terminated as described
in the Power Supply Decoupling section.
2. Minimize the distance (< 0.25”) from the
power supply pins to high frequency 0.1-µF
decoupling capacitors. At the device pins, the
ground and power plane layout should not be in
close proximity to the signal I/O pins. Avoid
narrow power and ground traces to minimize
inductance between the pins and the decoupling
capacitors. Note that each millimeter of a line,
that is narrow relative to its length, has ~ 0.8 nH
of inductance. The power supply connections
should always be decoupled with the recommended capacitors. If not properly decoupled,
distortion performance is degraded. Larger
(6.8-µF to 22-µF) decoupling capacitors, effective
at lower frequency, should also be used on the
main supply lines, preferably decoupled from the
amplifier and mid- and high-frequency capacitors
by a ferrite bead. See the Power Supply Decoupling Techniques section. The larger caps may be
placed somewhat farther from the device and
may be shared among several devices in the
same area of the PC board. A very low inductance path should be used to connect the inverting pin of the amplifier to ground. A minimum
of 5 vias as close to the part as possible is
recommended.
3. Careful selection and placement of external
components preserves the high frequency
performance of the THS4302. Resistors should
be a low reactance type. Surface-mount resistors
work best and allow a tighter overall layout.
Axially-leaded parts do not provide good high
frequency performance, because they have ~0.8
THS4302
www.ti.com
nH of inductance for every mm of current path
length. Again, keep PC board trace length as
short as possible. Never use wirewound type
resistors in a high frequency application. Because
the output pin and inverting input pin are the most
sensitive to parasitic capacitance, always position
the terminating resistors, if any, as close as
possible to the noninverting and output pins.
Even with a low parasitic capacitance shunting
the external resistors, excessively high resistor
values can create significant time constants that
can degrade performance. Good axial metal-film
or surface-mount resistors have approximately
0.2 pF in shunt with the resistor.
4. 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 (50 mils to 100 mils)
should be used, preferably with ground and
power planes opened up around them. Estimate
the total capacitive load and set RISO from the
plot of recommended RISO vs Capacitive Load.
Low parasitic capacitive loads (<4 pF) may not
need an RISO because THS4302 amplifiers are
nominally compensated to operate with a 2-pF
parasitic load. Higher parasitic capacitive loads
without an RISO are allowed as the signal gain
increases (increasing the unloaded phase margin). If a long trace is required, and the 6-dB
signal loss intrinsic to a doubly-terminated transmission line is acceptable, implement a matched
impedance transmission line using microstrip or
stripline techniques (consult an ECL design handbook for microstrip and stripline layout techniques). 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 THS4302 is used
as well as a terminating shunt resistor at the input
of the destination device. Remember also that the
terminating impedance is the parallel combination
of the shunt resistor and the input impedance of
the destination device: this total effective impedance should be set to match the trace impedance. If the 6-dB attenuation of a doubly
terminated transmission line is unacceptable, a
long trace can be series-terminated at the source
end only. Treat the trace as a capacitive load in
this case, and set the series resistor value as
shown in the plot of RISO vs Capacitive Load. This
does not preserve signal integrity as well as a
doubly terminated line. If the input impedance of
the destination device is low, there is some signal
attenuation due to the voltage divider formed by
the series output into the terminating impedance.
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
A 50-Ω environment is normally not necessary on
board as long as the lead lengths are short, and
in fact, a higher impedance environment improves distortion as shown in the distortion versus load plots. Uncontrolled impedance traces
without double termination results in reflections at
each end, and hence, produces PCB resonances.
It is recommended that if this approach is used,
the trace length be kept short enough to avoid
resonances in the band of interest. For guidance
on useful lengths, use equation (1) given in the
Power Supply Decoupling Techniques section for
approximate resonance frequencies vs trace
length. This relation provides an upper bound on
the resonant frequency, because additional capacitive coupling to the trace from other leads or
the ground plane causes extra distributed loading
and slows the signal propagation along the trace.
5. Socketing a high-speed part like the THS4302
is not recommended. The additional lead length
inductance and pin-to-pin capacitance introduced
by the socket creates an extremely troublesome
parasitic network, which can make it almost
impossible to achieve a smooth, stable frequency
response. Best results are obtained by soldering
the THS4302 onto the board.
PowerPAD™ DESIGN CONSIDERATIONS
The THS4302 is available in a thermally enhanced
PowerPAD family of packages. These packages are
constructed using a downset leadframe on which the
die is mounted [see Figure 49(a) and Figure 49(b)].
This arrangement results in the lead frame being
exposed as a thermal pad on the underside of the
package [see Figure 49(c)]. Because this thermal pad
has direct thermal contact with the die, excellent
thermal performance can be achieved by providing a
good thermal path away from the thermal pad.
The PowerPAD package allows both assembly and
thermal management in one manufacturing operation.
During the surface-mount solder operation (when the
leads are being soldered), the thermal pad can also
be soldered to a copper area underneath the package. Through the use of thermal paths within this
copper area, heat can be conducted away from the
package into either a ground plane or other heat
dissipating device.
The PowerPAD package represents a breakthrough
in combining the small area and ease of assembly of
surface mount with the heretofore awkward mechanical methods of heatsinking.
17
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
DIE
Side View (a)
DIE
End View (b)
Bottom View (c)
Figure 49. Views of Thermally Enhanced Package
Although there are many ways to properly heatsink
the PowerPAD package, the following steps illustrate
the recommended approach.
0.144
0.049
0.012
Pin 1
0.0095
0.015
0.144
0.0195 0.0705
0.010
vias
0.032
0.030
0.0245
Top View
Figure 50. PowerPAD PCB Etch and Via Pattern
PowerPAD™ PCB LAYOUT
CONSIDERATIONS
1. Prepare the PCB with a top side etch pattern as
shown in Figure 50. There should be etch for the
leads as well as etch for the thermal pad.
2. Place five holes in the area of the thermal pad.
They holes should be 13 mils in diameter. Keep
them small so that solder wicking through the
holes is not a problem during reflow.
3. Additional vias may be placed anywhere along
the thermal plane outside of the thermal pad
area. They help dissipate the heat generated by
the IC. These additional vias may be larger than
the 13-mil diameter vias directly under the thermal pad. They can be larger because they are
not in the thermal pad area to be soldered, so
that wicking is not a problem.
4. Connect all holes to the internal ground plane.
5. When connecting these holes to the ground
plane, do not use the typical web or spoke via
connection methodology. Web connections have
18
a high thermal resistance connection that is
useful for slowing the heat transfer during
soldering operations. This resistance makes the
soldering of vias that have plane connections
easier. In this application, however, low thermal
resistance is desired for the most efficient heat
transfer. Therefore, the holes under the IC
PowerPAD package should make their connection to the internal ground plane, with a complete
connection around the entire circumference of the
plated-through hole.
6. The top-side solder mask should leave the terminals of the package and the thermal pad area
with its five holes exposed. The bottom-side
solder mask should cover the five holes of the
thermal pad area. This prevents solder from
being pulled away from the thermal pad area
during the reflow process.
7. Apply solder paste to the exposed thermal pad
area and all of the IC terminals.
8. With these preparatory steps in place, the IC is
simply placed in position and run through the
solder reflow operation as any standard
surface-mount component. This results in a part
that is properly installed.
The next consideration is the package constraints.
The two sources of heat within an amplifier are
quiescent power and output power. The designer
should never forget about the quiescent heat generated within the device, especially multi-amplifier devices. Because these devices have linear output
stages (Class AB), most of the heat dissipation is at
low output voltages with high output currents.
The other key factor when dealing with power dissipation is how the devices are mounted on the PCB.
The PowerPAD devices are extremely useful for heat
dissipation. But, the device should always be
soldered to a copper plane to fully use the heat
dissipation properties of the PowerPAD. The SOIC
package, on the other hand, is highly dependent on
how it is mounted on the PCB. As more trace and
copper area is placed around the device,
ΘJA
decreases and the heat dissipation capability increases. For a single package, the sum of the RMS
output currents and voltages should be used to
choose the proper package.
THERMAL ANALYSIS
The THS4302 device does not incorporate automatic
thermal shutoff protection, so the designer must take
care to ensure that the design does not violate the
absolute maximum junction temperature of the device. Failure may result if the absolute maximum
junction temperature of 150° C is exceeded.
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
The thermal characteristics of the device are dictated
by the package and the PC board. For a given ΘJA,
maximum power dissipation for a package can be
calculated using the following formula.
Tmax–T A
P Dmax JA
where:
PDmax is the maximum power dissipation in the amplifier (W).
Tmax is the absolute maximum junction temperature (°C).
TA is the ambient temperature (°C).
θJA = θJC + θCA
θJC is the thermal coefficient from the silicon junctions to
the case (°C/W).
θCA is the thermal coefficient from the case to ambient air
(°C/W).
(1)
The THS4302 is offered in a 16-pin leadless MSOP
with PowerPAD. The thermal coefficient for the
MSOP PowerPAD package is substantially improved
over the traditional packages. Maximum power
dissipation levels are depicted in the graph below.
The data for the RGT package assumes a board
layout that follows the PowerPAD layout guidelines
referenced above and detailed in the PowerPAD
application notes in the Additional Reference Material
section at the end of the data sheet.
PD - Maximum Power Dissipation - W
7
6
5
16-Pin RGT Package
4
3
2
1
0
-40
-20
0
20
40
60
TA - Ambient Temperature - °C
80
θJA = 39.5°C/W for 16-Pin MSOP (RGT)
TJ = 150°C, No Airflow
Figure 51. Maximum Power Dissipation vs
Ambient Temperature
When determining whether or not the device satisfies
the maximum power dissipation requirement, it is
important to consider not only quiescent power dissipation, but also dynamic power dissipation. Often
maximum power is difficult to quantify because the
signal pattern is inconsistent, but an estimate of the
RMS power dissipation can provide visibility into a
possible problem.
DESIGN TOOLS
Evaluation Fixtures
Information
and
Application
Support
Texas Instruments is committed to providing its customers with the highest quality of applications support. To support this goal, an evaluation board has
been developed for the THS4302 operational amplifier. The evaluation board is available and easy to
use allowing for straight-forward evaluation of the
device. This evaluation board can be obtained by
ordering through the Texas Instruments Web site,
www.ti.com, or through your local Texas Instruments
Sales Representative. A schematic for the evaluation
board with default component values is shown in
Figure 52. Unpopulated footprints are shown to provide insight into design flexibility
Computer simulation of circuit performance using
SPICE is often useful when analyzing the performance of analog circuits and systems. This is particularly true for video and RF amplifier circuits where
parasitic capacitance and inductance can have a
major effect on circuit performance. A SPICE model
for the THS4500 family of devices is available
through the Texas Instruments web site (www.ti.com).
The Product Information Center (PIC) is available for
design assistance and detailed product information.
These models do a good job of predicting small
signal ac and transient performance under a wide
variety of operating conditions. They are not intended
to model the distortion characteristics of the amplifier,
nor do they attempt to distinguish between the
package types in their small signal ac performance.
Detailed information about what is and is not modeled
is contained in the model file itself.
19
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
VS+
FB2
J3
C2
22 µF
+
12 11 10
13
NC
14
C4
0.1 µF
R5
30.1 Ω
_
PD
R4
49.9 Ω
47 pF
9
+
J6
C9
*
Rf
Rg
J1
VI
C6
U1
8
7
6
5
R2
49.9 Ω
16
J2
VO
R3
*
C1
1 2
1 µF
VS-
3
C7
*
J4
C3
22 µF
4
+
C8
47 pF
FB1
C5
0.1 µF
R4
30.1 Ω
* = Not populated
Figure 52. Typical THS4302 EVM Circuit Configuration
Figure 53. THS4302EVM Layout
(Top Layer and Silkscreen Layer)
20
Figure 54. THS4302EVM
Board Layout
(Ground Layers 2 and 3)
Figure 55. THS4302EVM
Board Layout
(Bottom Layer)
THS4302
www.ti.com
SLOS403G – OCTOBER 2002 – REVISED JANUARY 2005
Table 1. BILL OF MATERIALS - THS4302RGT EVM
ITEM
DESCRIPTION
SMD SIZE
REFERENCE
DESIGNATOR
PCB
QUANTITY
MANUFACTURER'S
PART NUMBER
1206
FB1, FB2
2
(Steward) HI1206N800R-00
D
C2, C3
2
(AVX) TAJD226K025R
(AVX) 08053G105ZAT2A
1
Bead, ferrite, 3 A, 80 Ω
2
Cap. 22 µF, tantalum, 25 V, 10%
3
Cap. 1 µF, ceramic, 25 V, Y5V
0805
C1
1
4
Open
0402
C6, C7
2
5
Cap. 47 pF, ceramic, 50 V, NPO
0402
C8, C9
2
(AVX) 04025A470JAT2A
6
Cap. 0.1 µF, ceramic, 16 V, X7R
0603
C4, C5
2
(AVX) 0603YC104KAT2A
7
Resistor, 30.1Ω , 1/16 W, 1%
0402
R4, R5
2
(KOA) RK73H1E30R1F
8
Open
0603
R3
1
9
Resistor, 49.9 Ω, 1/16 W, 1%
0603
R1, R2
2
(Phycomp)
9C06031A49R9FKRFT
10
Jack, banana receptance, 0.25” dia. hole
J3, J4, J5
3
(HH Smith) 101
11
Test point, red
J6
1
(Keystone) 5000
12
Test point, black
TP1
1
(Keystone) 5001
13
Connector, edge, SMA PCB jack
J1, J2
2
(Johnson) 142-0701-801
14
IC THS4302
U1
1
(TI) THS4302RGT
15
Standoff, 4-40 hex, 0.625” length
4
(Keystone) 1808
16
Screw, phillips, 4-40, 0.250”
4
SHR-0440-016-SN
17
Board, printed-circuit
1
(TI) EDGE # 6443548 Rev. C
ADDITIONAL REFERENCE MATERIAL
•
•
PowerPAD Made Easy, application brief (SLMA004)
PowerPAD Thermally Enhanced Package, technical brief (SLMA002)
21
PACKAGE OPTION ADDENDUM
www.ti.com
8-Aug-2005
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
THS4302RGTR
ACTIVE
QFN
RGT
16
3000 Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
THS4302RGTRG4
ACTIVE
QFN
RGT
16
3000 Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
THS4302RGTT
ACTIVE
QFN
RGT
16
250
CU NIPDAU
Level-2-260C-1 YEAR
Green (RoHS &
no Sb/Br)
Lead/Ball Finish
MSL Peak Temp (3)
(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.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS) or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
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