75 Ohm RF Amplifier
50-1002 MHz
Overview
TAT7467H
Preliminary Datasheet
The TAT7467 is a 75 Ohm true differential RF Amplifier covering medium power applications in the CATV band.
The TAT7467 includes on-chip linearization to improve 3rd order distortion performance while maintaining low
power consumption on a 5v supply. It is fabricated using 6-inch GaAs pHEMT technology to optimize
performance and cost.
Features & Applications
•
•
•
•
75 Ohm, 40-1300 MHz Bandwidth
Meets DOCSIS 3.0 Output Requirements
On-chip Linearization for Third-order Efficiency
Power Consumption: 5V, 350-380mA. SOIC-8
•
•
•
•
•
Replacement for 5v SOIC-8 amplifiers
Edge QAM Output Stage
MDU Output
Distribution amplifiers
Transmitter Driver amplifier
Applications
1
8
Pin Configuration
Pin No.
1
2
3
4
5
6
7
8
Exposed Slug
Pin Name
RF IN A
LINA
LINB
RF IN B
RF OUT B
BIAS 2
BIAS 1
RF OUT A
GND
Description
RF Input
Linearizer
Linearizer
RF Input
RF Output
Biasing
Biasing
RF Output
Ground
2
L
I
N
7
3
6
4
5
Target Specifications: TAT7467H RF Amplifier
(Typical values, in Application Circuit)
Characteristic
Bandwidth
RF Gain
Gain Flatness
Noise Figure
Input Return Loss
Output Return Loss
Adjacent Triple Beats (3 tones, each 60 dBmV)
Equiv Harmonics (3 tones, each 60 dBmV)
Notes
1002 MHz
Typical
50-1002 MHz
16.5
0.75
4.7
-18
-23
-65
-70
Unit
MHz
dB
+/- dB
dB
dB
dB
dBc
dBc
To 1002 MHz
To 1002 MHz
2 MHz spacing
2 MHz spacing
Idd
(note: see definition of terms in Performance Data section)
5V
380
mA
2255 Challenger Way, Santa Rosa, CA 95407
707-526-4498
www.triaccesstech.com
Page 1
Proprietary and Confidential
Specifications subject to change, R90503
Application Overview
The TAT7467 is a flexible 5v differential amplifier for medium power CATV applications.
The amplifier of the TAT7467 was specially designed to work with on-chip linearization to provide 3
rd
order distortion improvement over a wide range of RF power levels and across the full CATV bandwidth.
Operation of the linearizer will not affect overall gain by more than 0.7 dB.
For any amplifier bias current, output 3
rd
order distortion may be improved by adjusting a small bias
current of the on-chip linearization circuit. The Application Schematic shows a microprocessor
controlled voltage source setting the linearizer currents. Alternate linearizer drive circuitry is possible;
consult TriAccess for discussion.
Bias current may be adjusted with changes to external components making the TAT7467 ideal for both
input and output gain stages in an EdgeQAM amplifier line-up. For output stage applications, bias
currents of between 300mA to 400mA are recommended. For input stage applications, bias currents of
230 to 280mA are recommended.
For best performance the TAT7467 bias may be controlled with an active bias circuit as shown in the
Application Schematic. The controlled current is referenced to a precision voltage source, commonly
found on microprocessors or from a low cost voltage reference.
The TAT7467 is built using a single die, which significantly improves its resulting circuit balance and
corresponding 2
nd
order distortion performance. For best 2
nd
order performance, an input balun using a
3
rd
wire construction may be used to improve the input phase balance going into the TAT7467.
The TAT7467 is packaged in an industry standard SOIC-8 package with a large exposed paddle to
enable good heatflow to a backside heatsink. At the maximum recommended bias current of 400mA,
the power consumption will be 2W. The TAT7467 is fabricated using a mature pHEMT process that has
demonstrated outstanding reliability performance on other TriAccess products. Please consult TriAccess
for further information.
2255 Challenger Way, Santa Rosa, CA 95407
707-526-4498
www.triaccesstech.com
Page 2
Proprietary and Confidential
Specifications subject to change, R90503
EdgeQAM Output Section Options
2 Stage EdgeQAM Output Sections
The TAT7467 provides enough gain to enable EdgeQAM
output sections to be designed with two gain stages
rather than three. Figure 1 shows how the TAT7468 or
TAT7469 can act as the input stage to drive the 7467.
The combined amplifier gain will be more than 33 dB. By
adjusting the bias downward, the 7467 may also be used
as the input stage.
The loss of the interstage variable attenuator will largely
determine which input stage device is the best choice.
Attenuators with large amounts of minimum attenuation
will require higher levels of linearity from the input stage
to preserve cascaded linearity. For those designs, the
7469 is the better choice.
Should most of the variable attenuation be placed on the
input side of the 1
st
stage, the linearity requirements of
the 1
st
stage may be relaxed. In this case, the lower
supply current of the 7468 provides further improvement
in power efficiency.
Attenuator
Attenuator
1
1
TAT7468
16 dB gain
5v, 150-200mA
OIP3 = 35 dBm
TAT7467B
17 dB gain
5v, 330-385mA
Attenuator
Attenuator
1
2
The gain of the 7467 in the Application Schematic is
typically 17 dB at 1000 MHz. The baluns used in the
Application Schematic include a third winding to improve
FIG. 1
the balance and control the 2
nd
order distortion terms.
The balun listed operates to 5 MHz and has high loss for a 1:1 balun. Alternate baluns can be built with
reduced loss. The 7467 amplifier gain with ideal baluns is over 18.5 dB at 1000 MHz.
TAT7469
17.5 dB gain
5v, 220-275mA
OIP3 = 39 dBm
TAT7467B
17 dB gain
5v, 330-385mA
Linearizer Operation
Third order distortion performance of the amplifier may be adjusted by controlling the VLIN terminal on
the Application Schematic. To disable the linearizer, set VLIN to 5v which will set the linearizer
currents, ILINA and ILINB to 0.
For best performance, VLIN may be adjusted over frequency and temperature. Use of the active bias in
the Application Schematic will make the optimum VLIN more consistent over temperature and part
variations.
Optimum VLIN for minimizing the adjacent channel distortions will be near the optimum VLIN to
minimize the 3
rd
order distortions. A compromise value of VLIN can be found that provides for both
good adjacent channel performance and 3
rd
harmonics.
2255 Challenger Way, Santa Rosa, CA 95407
707-526-4498
www.triaccesstech.com
Page 3
Proprietary and Confidential
Specifications subject to change, R90503
Application Schematic
L3
910n
+5V
380mA
1
(with TAT7467B)
R6
1
VCC
C1
0.1u
C2
1.0
(1206)
VX
0.1u
C4
0.1u
R7
10K
micro
reference
1.24v
may be
substituted
3
VCC
R8
-
5
Vcc
1
MMBT2907A
B
1
3 E
R12
10K
4
+
no load
Q1
2 C
(1206)
1
U3
2
Vee
3
2
U1
R11
100
R10
0.01u
5.6K
VDRIVE
1
C11
R9
10K
LMV431
SOT23-5
C12
0.01u
0.01u
C10
ISENSE
ACTIVE BIAS
RF
INPUT
C7
0.01u
L1
L4
1.8n
0.01uF
500n
560pF
C5
INPUT A
1
8
OUTPUT A
TAT 7467BE
T1
1
3
C15
-
7
1pF
R1
1.0K
ILINA
1
4
U2
LINA
2
C13
ISENSE
T2
+
L
I
N
R3
1
3
1
2
BIAS1
2
1
1
2
C9
0.01u
ILINB
3
1
B1
+
6
2
1
1.5
(1206)
VDRIVE
1
2
4
2
-
TC1-33-75G2+
TC1-33-75G2+
R2
C6
1.0K
LINB
4
BIAS2
5
B2
C14
L5
2.2n
560pF
SOIC-8
BACKSIDE
PADDLE
VLIN
from micro
0.01uF
ILINA
ILINB
INPUT B
OUTPUT B
L2
500n
R5
200
RF
OUTPUT
VX
0.01u
C3
R4
0.1u
510
C8
PROPRIETARY INFORMATION
LINEARIZER CONTROL
FIG. 2
TRIACCESS TECHNOLOGIES, 2008
2255 Challenger Way, Santa Rosa, CA 95407
707-526-4498
www.triaccesstech.com
Page 4
Proprietary and Confidential
Specifications subject to change, R90503
Bill of Materials
REFERENCE
DESIGNATOR
B1
B2
C1,2,3,4
C5,6,7,8,9,10,11,12
C13,14
C15
J1,2
L1,2
L3
L4
L5
Q1
R1,2
R3
R4
R5
R6
R7,8,9
R10
R11
R12
T1,2
U1
U2
U3
VALUE /
DESCRIPTION
Ferrite Bead
Ferrite Bead
0.1uF
0.01uF
560pF
1pF
SMB connector
500nH
910nH
1.8nH
2.2nH
PNP transistor
1.0K ohms
1.5 ohms, 1% (1206)
510 ohms
200 ohms
1.0 ohm (1206)
10K ohms
5.6K ohms
100 ohms
no load (1206)
1:1 Balun
Op Amp (rail-rail)
RFIC Amplifier
Voltage reference
MFG
MuRata
MuRata
KOA
AVX
AVX
AVX
Johnson
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Diodes Inc
Dale
KOA
Dale
Dale
KOA
Dale
Dale
Dale
Dale
MiniCircuits
National
TriAccess
National
MFG PN
BLM15EG221SN1
BLM15HG102SN1
X7R0402CTTP104K
0402YC103KAT2A
04025C561KAT2A
04025A1R0BAT2A
131-8701-206
LQH31HNR50K
1008AF-901XKL
0402CS-1N8XJLW
0402CS-2N2XJLW
MMBT2907A
CRCW04021K00FKED
RK73H2BLTD1R50F
CRCW0402510RJNED
CRCW0402200RJNED
RK73H2BTTD1R00F
CRCW040210K0JNED
CRCW04025K60JNED
CRCW0402100RJNED
TBD
TC1-33-75G2+
LM7301
TAT 7467BE
LMV431
2255 Challenger Way, Santa Rosa, CA 95407
707-526-4498
www.triaccesstech.com
Page 5
Proprietary and Confidential
Specifications subject to change, R90503
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