Application Note No. 098

Application Note, Rev. 1.1, April 2012
Application Note No. 098
Broadband Amplifier MMICs for TV Tuner
Applications
RF & Protection Devices
Edition 2012-04-25
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2012.
All Rights Reserved.
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Application Note No. 098
Application Note No. 098
Revision History: 2012-04-25, Rev. 1.1
Previous Version: 2006-11-28, Rev. 1.0
Page
Subjects (major changes since last revision)
7
Bill of Matrials updated
Application Note
3
Rev. 1.1, 2012-04-25
Application Note No. 098
Broadband Amplifier MMICs in TV Tuner Applications
1
Broadband Amplifier MMICs in TV Tuner Applications
Over the last few years there has been a clear trend in television to move from the classical TV-set out to more
mobile platforms like notebooks, cell phones and PDAs. Especially the introduction of digital terrestrial television
in many countries and the more and more evolving hand-held television standards like DVB-H and T-DMB support
this evolution.
With television going mobile the antennas are getting smaller, resulting in a loss in antenna gain. It requires an
additional LNA with low noise figure to keep up a good reception of the TV signal, no matter if the TV tuner’s RF
frontend uses the classical three-band tuner (Figure 1) or the more space saving silicon tuner (also called double
conversion tuner or up-down converter, Figure 2). Particularly the silicon tuner has the need for and external LNA
as tuner ICs in general tend to have high noise figures and the silicon tuner approach doesn’t implement any prestages including an RF MOSFET.
LNAs for TV tuner applications have to fulfill challenging requirements. They have to cover a very wide frequency
range and need to handle both extremely high and low signal levels at the amplifiers input. These different signal
levels require an LNA that offers both a good noise figure as well as a high linearity.
Broadband design, low noise figure and high linearity make Infineon’s Darlington broadband amplifier family the
LNAs of choice for TV tuner applications.
VHF low 47 ... 160MHz
RF Input
VHF high 160 ... 470MHz
LNA
Tuner IC
ESD
Protection
UHF 470 ... 860MHz
3Band.vsd
RF MOSFETs
Figure 1
Classical Three-Band Tuner
SAW
GSM
Rejection
LNA
Demod
ESD
Protection
VGA
Mixer
VCO 1
Si-Tuner
Figure 2
Mixer
VCO 2
Si_Tuner.vsd
Silicon Tuner
Application Note
4
Rev. 1.1, 2012-04-25
Application Note No. 098
Infineon’s Darlington Broadband Amplifier Family
2
Infineon’s Darlington Broadband Amplifier Family
2.1
Description of the Devices
Infineon’s Darlington amplifier family consists of three different LNAs:
•
•
•
BGA612
BGA614
BGA616
Out, 3
In, 1
GND, 2,4
Figure 3
schematic1.vsd
Equivalent Circuit of the Broadband LNAs
These types are matched, general purpose broadband MMIC amplifiers in Darlington configuration. They are
implemented in Infineon’s high ft, low noise B7HF Silicon Germanium technology.
The devices’ 3 dB bandwidth covers DC up to 2.7 GHz, Table 1 shows a collection of the most important electrical
parameters of the three amplifiers. This data is an excerpt of the devices’ data sheets and does not contain any
external losses.
Table 1
Comparison of Key Parameters1)
Parameter
BGA612
BGA614
BGA616
Unit
20
40
60
mA
Gain
17.0
18.5
18.5
dB
Noise Figure
2.25
2.2
2.8
dB
Input 1dB Compression Point
-9
-6
0
dBm
Input 3rd Order Intercept Point
0
6
11
dBm
>15
>15
>15
dB
Typ. operating current
Return Loss
1) Measured at 1 GHz
This exceptional performance, enabled by Infineon’s 70 GHz B7HF Silicon Germanium process, combined with
reduced external component count and ease of use, make these broadband amplifiers an ideal choice for a wide
variety of RF applications up to 2.5 GHz. The high linearity make them especially useful for TV applications.
The Darlingtons’ simplicity, flexibility and ease of use streamlines the RF design process and allows for shorter
design cycles and fast time-to-market in today’s fast-paced competitive business environment
Application Note
5
Rev. 1.1, 2012-04-25
Application Note No. 098
Infineon’s Darlington Broadband Amplifier Family
2.2
TV Amplifier Design using BGA614
This chapter describes the design of a general purpose broadband amplifier for the frequency band between
50 MHz and 1 GHz using BGA614 as an example. Designing an amplifier with BGA612 or BGA616 is almost
exactly the same procedure, they require only different bias resistors.
Implementing an amplifier circuit using BGA614 is a simple straightforward task. As both input and output are
matched and BGA614 is an unconditionally stable device, there is no need to work on the RF portion of the
amplifier design, leaving only DC biasing issues to contend with. The broadband 50 Ω match also eases and
speeds integration of the MMIC with any external filters used.
Figure 5 and Table 2 show the typical schematic and bill of material when using one of the three MMICs as an
LNA in TV tuner applications.
Device Current I D = f(VCC)
RBias = parameter in Ω
80
0
70
16
27
47
60
68
I D [mA]
50
40
100
30
150
20
10
0
0
1
2
3
4
5
6
VCC [V]
Figure 4
Device Current vs. Supply Voltage, Parameter is R1
The Darlingtons are biased via their RF output pin (pin 3). Figure 4 shows the dependence of BGA614’s current
consumption on the supply voltage for different values of the bias Resistor R1. R1 stabilizes the supply current by
using voltage feedback. For BGA612 and BGA616 exist similar plots which can be found in the devices’ data
sheets.
In principle it is possible to bias BGA614 without an additional resistor. However, omitting R1 will lead to increased
unit-to-unit variation in operating current due to the usual variation in the DC Beta (hFE) of the internal transistor
cells. It is therefore recommended that R1 be used in all cases.
The inductor L1 in series with resistor R1 is necessary for RF blocking. C3 and C4 serve as RF bypass at the
voltage supply.
The capacitors C1 and C2 are DC blocks as there is DC voltage present on pin 1 and pin 3. These capacitors are
needed only if there is no DC open circuit on the input and output of the amplifier. For example, if a filter that
presents a DC open circuit is used ahead of or after the BGA614, the corresponding DC blocking capacitor may
be omitted.
Application Note
6
Rev. 1.1, 2012-04-25
Application Note No. 098
Infineon’s Darlington Broadband Amplifier Family
Vcc
5V
C4
8.2nF
R1
see BOM
C1
8.2nF
In
1
L1
270nH
4
Q1
BGA61x
2
C3
8.2nF
C2
8.2nF
3
Out
schematic.vsd
Figure 5
Typical Schematic
Table 2
Bill of Materials
Name
Unit
Manufacturer
Function
C1
8.2
nF
Various
DC block
C2
8.2
nF
Various
DC block
C3
8.2
nF
Various
RF bypass
C4
8.2
nF
Various
RF bypass
L1
270
nH
Various
RF choke
R1
120 @ BGA612
68 @ BGA614
15 @ BGA616
Ω
Various
Biasing
Q1
BGA612
BGA614
BGA616
Infineon Technologies
Broadband SiGe MMIC
Application Note
Value
7
Rev. 1.1, 2012-04-25
Application Note No. 098
Measurement Results
3
Measurement Results
Please note that the data displayed in the following chapters includes connector losses as well as board losses.
In other words, the reference planes of the measurements are the input and output connectors.
3.1
BGA612
Table 3
Measured Electrical Performance on Evaluation Board1)
Parameter
50 MHz
500 MHz
1000 MHz
Unit
Supply Voltage
5
V
Biasing Resistor
120
Ω
DC current
20.8
mA
Gain
17.0
17.4
16.7
dB
Noise Figure
2.2
2.4
2.25
dB
-11
-10
-10
dBm
Input 1dB Compression Point
rd
Input 3 Order Intercept Point
2)
3)
---
2.5
1.5
dBm
Input Return Loss
11.3
17.1
14.3
dB
Output Return Loss
9.7
17.1
14.9
dB
Reverse Isolation
20.6
20.4
20.5
dB
1) Including all PCB losses
2) Input power -25 dBm / tone; Δf = 1 MHz
3) No power combiner for this frequency available in lab
18
Gain (dB)
16
14
12
10
8
50
100
1000
Frequency (MHz)
5000
Gain_612.vsd
Figure 6
Gain vs. Frequency
Application Note
8
Rev. 1.1, 2012-04-25
Application Note No. 098
Measurement Results
0
Matching (dB)
-5
-10
S22
-15
S11
-20
-25
50
100
1000
Frequency (MHz)
5000
s1122_612.vsd
Figure 7
Input Return Loss and Output Return Loss vs. Frequency
Reverse Isolation (dB)
-5
-10
-15
-20
-25
50
100
1000
Frequency (MHz)
5000
S12_612.vsd
Figure 8
Reverse Isolation vs. Frequency
Application Note
9
Rev. 1.1, 2012-04-25
Application Note No. 098
Measurement Results
Stability Factor / Measure
2
1.5
K>1
1
B1>0
0.5
0
50
100
1000
Frequency (MHz)
5000
K_612.vsd
Figure 9
Stability Factor K and Stability Measure B1 vs. Frequency
Application Note
10
Rev. 1.1, 2012-04-25
Application Note No. 098
Measurement Results
3.2
BGA614
Table 4
Measured Electrical Performance on Evaluation Board1)
Parameter
50 MHz
500 MHz
1000 MHz
Unit
Supply Voltage
5
V
Biasing Resistor
68
Ω
DC current
39.2
mA
Gain
18.7
19.0
18.1
dB
Noise Figure
2.15
2.35
2.2
dB
-6.5
-5.5
-5
dBm
3)
---
4.5
4.5
dBm
11.6
17.5
14.3
dB
Input 1dB Compression Point
rd
Input 3 Order Intercept Point
2)
Input Return Loss
Output Return Loss
9.8
17.6
15.3
dB
Reverse Isolation
22.4
21.7
21.6
dB
1) Including all PCB losses
2) Input power -20 dBm / tone; Δf = 1 MHz
3) No power combiner for this frequency available in lab
20
18
Gain (dB)
16
14
12
10
8
50
100
1000
Frequency (MHz)
5000
Gain_614.vsd
Figure 10
Gain vs. Frequency
Application Note
11
Rev. 1.1, 2012-04-25
Application Note No. 098
Measurement Results
0
Matching (dB)
-5
-10
S22
-15
S11
-20
-25
50
100
1000
Frequency (MHz)
5000
S1122_614.vsd
Figure 11
Input Return Loss and Output Return Loss vs. Frequency
Reverse Isolation (dB)
-5
-10
-15
-20
-25
50
100
1000
Frequency (MHz)
5000
s12_614.vsd
Figure 12
Reverse Isolation vs. Frequency
Application Note
12
Rev. 1.1, 2012-04-25
Application Note No. 098
Measurement Results
Stability Factor / Measure
2
1.5
K>1
1
B1>0
0.5
0
50
100
1000
Frequency (MHz)
5000
K_614.vsd
Figure 13
Stability Factor K and Stability Measure B1 vs. Frequency
Application Note
13
Rev. 1.1, 2012-04-25
Application Note No. 098
Measurement Results
3.3
BGA616
Table 5
Measured Electrical Performance on Evaluation Board1)
Parameter
50 MHz
500 MHz
1000 MHz
Unit
Supply Voltage
5
V
Biasing Resistor
15
Ω
DC current
59.6
mA
Gain
18.5
19.0
18.1
dB
Noise Figure
2.8
2.9
2.8
dB
-1
0
1
Input 1dB Compression Point
rd
Input 3 Order Intercept Point
2)
3)
Input Return Loss
---
9
11.6
17.5
dBm
dBm
14.3
dB
Output Return Loss
9.8
17.6
15.3
dB
Reverse Isolation
22.4
21.7
21.6
dB
1) Including all PCB losses
2) Input power -20 dBm / tone; Δf = 1 MHz
3) No power combiner for this frequency available in lab
20
Gain (dB)
18
16
14
12
10
50
100
1000
Frequency (MHz)
5000
Gain_616.vsd
Figure 14
Gain vs. Frequency
Application Note
14
Rev. 1.1, 2012-04-25
Application Note No. 098
Measurement Results
0
Matching (dB)
-5
-10
S22
-15
S11
-20
-25
50
100
1000
Frequency (MHz)
5000
s1122_616.vsd
Figure 15
Input Return Loss and Output Return Loss vs. Frequency
Reverse Isolation (dB)
-5
-10
-15
-20
-25
50
100
1000
Frequency (MHz)
5000
S12_616.vsd
Figure 16
Reverse Isolation vs. Frequency
Application Note
15
Rev. 1.1, 2012-04-25
Application Note No. 098
Measurement Results
Stability Factor / Measure
2
1.5
K>1
1
B1>0
0.5
0
50
100
1000
Frequency (MHz)
5000
K_616.vsd
Figure 17
Stability Factor K and Stability Measure B1 vs. Frequency
Application Note
16
Rev. 1.1, 2012-04-25