INFINEON BGA430, BGB540 User Manual

A

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pplications Note No. 074

Silicon Discretes

A 35 dB Gain-Sloped LNB I.F. Amplifier for Direct Broadcast Satellite

Television Applications using the BGA430 & BGB540 Silicon MMICs

Gain = 32 – 37 dB from 950 – 2150 MHz (positive gain slope)

•

Low Power Consumption: 40mA at +5.0 Volts

•

Exceptionally low Noise Figure: less than 3 dB

•

Low Cost, Low Parts Count

•

High Reverse Isolation

•

Output Compression point: +1 dBm minimum

•

(May be increased with higher DC bias level)

Suitable for European, Asian & North American DBS

•

LNB I.F. Amplifier Chains for 950 – 1450 and 950 – 2150 MHz

1. Overview

Infineon’s BGA430 Broad Band High Gain
Low Noise Amplifier and BGB540 Active
Biased Transistor are shown in an

Intermediate-Frequency (“I.F.”) amplifier
application targeted for the I.F. chains of
European, Asian and North American Direct­Broadcast Satellite (DBS) Low Noise Block
Amplifier / Downconverters (LNBs).

A summary of key performance parameters for
the complete LNB I.F. Amplifier is given in Table

1 to the right. The reader is referred to
Appendix A on page 21 for complete electrical

data including minimum, maximum, mean value,
and standard deviation for the lot of Printed
Circuit Boards (PCBs) tested. Appendix B on
page 22 gives information on performance over
the –40 to +85 °C temperature range.

Section 2 of this applications note provides a
brief description of the BGA430 and BGB540
MMICs. Section 3 gives some general Direct
Broadcast Satellite system information, and is
included to provide a general background.
Section 4 provides details on the PC Board
used, including photos, a Bill of Material (BOM)
and a PCB cross-sectional diagram. Section 5

describes using the BGA430 MMIC as a stand­alone DBS I.F. Amplifier block, and covers
design issues unique to BGA430. Section 6
addresses the question “why might one want a
positive gain slope I.F. Amplifier” and Section 7
gives measurement results on the complete
gain-sloped amplifier using both BGA430 &
BGB540.

Table 1. Typical performance for the
complete BGA430+BGB540 LNB I.F.
Amplifier.

Conditions: Temperature=25°C, V=5.0 Volts, n=25 units,

=50Ω, network analyzer source power = -40 dBm

Z

S=ZL

Parameter

Input Return Loss, dB
Gain, dB
Reverse Isolation, dB
Output Return Loss, dB
Noise Figure, dB
Output P
Input IP3, dBm

1dB

Please note that the reference planes for all
measurement data shown in Table 1 are at the
PC board’s SMA RF connectors; e.g. no PCB
loss is extracted from the numbers given.

Frequency, MHz

950 1450 2150

26.0 27.3 12.0

33.0 37.2 37.2
>50 >50 >50

13.7 13.4 13.1

2.4 2.4 2.6

, dBm

+1.7 +4.9 +7.9

-20.8 -22.5 -18.9

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pplications Note No. 074

Silicon Discretes

2. Description of BGA430 and BGB540

The BGA430 is a three-stage, 50 ohm, internally
matched, unconditionally stable MMIC fabricated
in Infineon’s well-proven, consistent and cost­effective 25 GHz transition frequency (f

) B6HF

T

bipolar process. The BGA430 only requires
three external elements – input / output DC
blocking capacitors, and a single decoupling
capacitor on the power supply pin. Depending
on the particular LNB performance
requirements, the BGA430 may be used as a
stand-alone I.F. amplifier block, or together with
the BGB540.

The BGB540 is an unmatched, active-biased RF
transistor produced in the 45 GHz f

B6Hfe

T

bipolar process. B6Hfe, derived from B6HF, is a
more advanced process with higher achievable
gains and lower noise figures. BGB540 uses an
internal current mirror for DC biasing. This
approach achieves some reduction in external
component count due to elimination of a number
of external DC bias circuit elements, while still
preserving the flexibility inherent in a fully
discrete transistor. The device bias current may
be adjusted via a single external resistor.
Furthermore, the internal current-mirror, being
located on the same chip as the RF transistor
cell, has excellent “thermal tracking” of the RF
transistor cell, providing for a more stable DC
operating point over temperature. The BGB540
preserves the cost-advantages of the simple 4­pin industry-standard SOT343 package.

A block diagram and package drawing for the
BGA430 and BGB540 are given in Figures 1 &
2, respectively. Note that for the BGB540, the
emitter areas of the current-mirror transistor cell
and the RF transistor cell are in the ratio of 1:10.
To set DC bias current for the BGB540, one
injects a current into pin 4, and the current
drawn by the RF transistor cell is 10 times the
current injected into pin 4, by virtue of the
current-mirror principle. The simplest DC bias
configuration for BGB540 involves using just a
single resistor between the power supply and
pin 4 – no RF choke or decoupling capacitor is
required on pin 4. The value of this bias resistor
– referred to as “ R

“ – required for a given

BIAS

device current can be determined from curves

given in the BGB540 datasheet. For lower
operating currents, the value of R
large, and therefore R

in series with the

BIAS

BIAS

becomes

power supply voltage behaves as a near-ideal
constant-current source. Otherwise, the
BGB540 is treated like a standard RF transistor,
with the normal procedures for impedance
matching, stability analysis, etc. being used.

Figure 1. BGA430 Block Diagram and

Package (SOT363).

4

GND2

3

RFout

5

GND1

2

GND1

6

RFin

BGA430 (B6HF) V

= 6.5 V, I

MAX

Bias

MAX

1

Vcc

= 35 mA

Figure 2. BGB540 Block Diagram and

Package (SOT343).

BFP540

C

Pin 3

Bias

Pin 4

1/10 BFP540

Base
Pin 1

BGB 540 B6HFe

VCE

= 4.5 V I

MAX

C MAX

= 80 mA

Emitter
Pin 2

3. General DBS System Information

A generic block diagram of a Direct Broadcast
Satellite Low Noise Block Amplifier /
Downconverter (LNB) is given in Figure 3 on
page 3. LNBs produced for the Direct Broadcast
Satellite consumer electronics market are
extraordinarily cost-sensitive, and cost issues
are usually the primary consideration in the LNB
design process.

A broadcast signal in the 12 GHz range is
transmitted from an orbiting satellite towards the
Earth’s surface. There are two orthogonal parts

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pplications Note No. 074

Silicon Discretes

of the composite signal – a vertically polarized
component, and a horizontally polarized
component. The two polarizations enable more
efficient use of the available bandwidth and
power. (The isolation between “vertical” and
“horizontal” radio signals permits a greater
number of channels to be simultaneously
broadcast within the available bandwidth than
would otherwise be expected.) The satellite’s
transmitted signal is received by an earth-based
antenna like that shown in the photo on page 1.
The signal is focused by the parabolic “dish”
antenna onto a waveguide integrated into the
LNB. The received signal travels a short
distance down the waveguide until reaching a
waveguide-to-microstripline transition that
carries the signal onto the LNB circuit board
assembly.

The LNB must be able to receive channels on
both the vertically and horizontally polarized
signals – and one way to do this is to have
essentially two different receiver front-ends as
shown in Figure 3 below.

Figure 3. Generic Block Diagram, "Single Output" Direct

Broadcast Satellite Television Block Downconverter (DBS LNB)

Cascaded Gain: approximately 55 - 60 dB; Cascaded Noise Figure: approximately 1 dB

Approximate Gain, dB =>

Approximate Noise Figure, dB =>100.5

0.7

12

-1.5

1.5

Various approaches and switching schemes are
employed in different LNB designs to enable the
end user(s) to select between channels riding on
either the horizontally or vertically polarized
signals. Each approach has its own unique cost
and performance trade-offs. Optimizing LNB
architectures to achieve performance
requirements while continuously reducing cost
as new, higher-performance and lower cost
semiconductor devices become available is a
challenging task.

A further complication to the switching
requirements is added if one wishes to have a
“dual output LNB” – e.g. an LNB that can drive
two different set-top boxes and television sets
simultaneously, allowing each TV to display a
different channel. (“Quad output” LNBs are also
available). One possible switching scheme for a
“single output LNB” is shown in Figure 3. Note
that the vertical / horizontal switching is done at
the I.F. Amplifier block. The BGA430 and
BGB540 are shown in the shaded I.F. Amplifier
section.

-10 to +8

7 to 12

- 4 30 to 45

4

3 to 7

LNB

U.S., Japan, Korea,

Latin America

11.45 - 12.75 GHz

(depending on region)

Horizontal

Polarization

LNA LNA

(Passive or Active)

BPF

Mixer

(Components in Shaded Area)

I.F. Amplifier

Local Oscillator

(DRO)

U.S., Japan, Korea,

Latin America:

Europe

10.7 - 12.75 GHz

(Two L.O.'s required for

full coverage)

Vertical

Polarization

AN 074 Rev E 3 / 24 19-November-2002

LNA LNA

in 10.5 - 11.25 GHz range

Audio + Video

to TV set

Europe:

10.6 GHz or

9.75 + 10.6 GHz
(dual DRO)

BPF

Mixer

(Passive or Active)

"Set Top Box"

(Channel Selector,
Demodulator, etc.)

(Vert. / Hor.)

Switch

BPF

Intermediate Frequency ("I.F.")

950 - 1450 MHz (North America)

950 - 2150 MHz (Europe, Asia)

IF Amp IF Amp

BGA430 + BGB540

75 ohm Coaxial Cable

To Set-Top Box

(75 ohm system)

RG-6, RG-6/U

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pplications Note No. 074

Silicon Discretes

After the waveguide to microstrip transition, the
signals enter a PC Board assembly. The signal
is amplified in two or more low noise amplifier
(LNA) stages and then hits a band pass filter.
The LNAs provide enough gain to boost the
level of the received signal such that the overall
receiver noise figure is dominated by the LNA
block itself. The LNA stages must have enough
gain and a sufficiently low noise figure to
minimize the noise floor for the entire receive
chain. Achieving enough gain and a low enough
noise figure at 12 GHz is costly, and anything
that can reasonably be done to relax the
requirements on the LNA section will reduce
cost.

The LNA is then followed by a band pass filter
(BPF) which provides for some rejection of out –
of-band signals and noise, as well as image
rejection. The amplified and filtered signal then
enters the mixer stage.

The types of simple, inexpensive mixers likely to
be used in an LNB will usually convert both the
desired input signal (12 GHz in this case) and an
undesired “image” frequency (10 GHz) to the
intermediate frequency (1 GHz for this example).
The band pass filter in front of the mixer stage
can attenuate any undesired signals or noise
present at the 10 GHz image frequency before it
hits the mixer stage, preventing the undesired
image from being down-converted on top of the
desired, down-converted 12 GHz input signal.
At present, most LNB manufacturers use one of
three main types of mixers:

1. GaAs FET used as a simple active mixer

2. GaAs FET with no DC bias applied ( “FET
resistive mixer”)

3. Schottky Diode based mixer

Some references for mixers are given in [1] and
[2] at the end of this applications note.

The FET active mixer will usually have
“conversion gain” while the FET resistive mixer
or Schottky diode mixers have “conversion loss”.
Conversion gain or loss is simply the ratio of the
amplitudes of the down-converted output I.F.

signal to the RF input signal. A poor noise figure
in the mixer stage, as well as high conversion
loss, places additional demands (and cost) on
both the LNA block up front, as well as the I.F.
amplifier which follows.

The down-converted I.F. signal undergoes
further band pass filtering and then is amplified
in the I.F. amplifier block. The I.F. amplifier is
the focus of this applications note, and is the
primary point of discussion regarding the
BGA430 and BGB540 Silicon MMICs. The I.F.
amplifier boosts the signal up to a reasonable
input level for the set top box. It is worth noting
that the system impedance in this area is 75
ohms, not 50 ohms, and that the coaxial cable
typically used (RG-6, RG-6/U or sometimes RG-

59) is very low cost, and has a relatively high
attenuation per unit length a the intermediate
frequency. Furthermore, the attenuation of the
cable increases with increasing frequency –
coaxial cable loss at 2150 MHz is higher than
cable loss at 950 MHz. Herein lies the reason

for designing an I.F. amplifier with a gain
slope that increases with increasing
frequency – this positive gain slope in the
I.F. amp will help to compensate out the
negative gain slope of the coaxial cable and
other RF front-end blocks.

4. Information on Printed Circuit Board

The PC board used in this applications note was
simulated within and generated from the

Eagleware GENESYS

®

[3] software package.
After simulations, CAD files required for PCB
fabrication, including Gerber 274X and Drill files,
were created within and output from GENESYS.
Photos of the PC board are provided in Figures
4, 5 and 6. A cross-sectional diagram is given
in Figure 7. A schematic diagram and a Bill Of
Material (BOM) for the complete BGA430 +
BGB540 I.F. Amplifier are given in Figures 8
and 9, respectively. The PC Board material
used is standard FR4. Note that each MMIC
may be tested individually; capacitor C3 (see
schematic) may be positioned to “steer” the RF
from the BGA430 output to the SMA connector
on the bottom of the PCB, or, C3 may be used
to link the track from this same RF connector to
the input of the BGB540. When testing the

AN 074 Rev E 4 / 24 19-November-2002

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pplications Note No. 074

Silicon Discretes

BGB540 stage alone, a zero-ohm “jumper”
needs to be used in place of R2. The total PCB
area consumed for the entire BGA430 +
BGB540 I.F. Amplifier is approximately 0.585 x

0.180 inch / 14.9 x 4.6 mm, or approximately 70

2

mm

. The total component count, including
both Silicon MMICs, is 16. Note that PCB area
and component count may be reduced markedly
if the end user is able to satisfy his or her I.F.
amplifier requirements by using the BGA430 as
a stand-alone part. The next section describes
the BGA430 as a stand-alone I.F. amplifier.

Figure 4. Top View of I.F. Amp PC Board.

Figure 6. Close-In Shot of PCB. BGA430 on
left, BGB540 on Right.

Figure 7. Cross-Section Diagram of I.F.
Amplifier Printed Circuit Board.

PCB CROSS SECTION

THIS SPACING CRITICAL !

Figure 5. Bottom View of I.F. Amp PC Board

0.010 inch / 0.254 mm

0.031 inch / 0.787 mm ?

LAYER FOR MECHANICAL RIGIDITY OF PCB, THICKNESS HERE NOT

CRITICAL AS LONG AS TOTAL PCB THICKNESS DOES NOT EXCEED

0.045 INCH / 1.14 mm (SPECIFICATION FOR TOTAL PCB THICKNESS:

0.040 + 0.005 / - 0.005 INCH; 1.016 + 0.127 mm / - 0.127 mm )

TOP LAYER

INTERNAL GROUND PLANE

BOTTOM LAYER

5. Using the BGA430 as a Stand-Alone I.F.
Amplifier Block

Provided that BGA430 gain magnitude, gain
curve and output power are adequate for the
user’s LNB system requirements, BGA430 may
be used as a very low-parts-count, low-cost
stand-alone LNB I.F. amplifier over the 950 –
2150 MHz range. Note that only 3 external

elements are typically required with BGA430:

1) an input DC blocking capacitor 2) an output
DC blocking capacitor 3) an RF bypass / RF
decoupling capacitor on the V

pin (Pin 1).

CC

Table 2 on page 8 summarizes the BGA430’s
typical performance and Figures 11 – 15 give
network analyzer screen shots of input / output
match, gain, and (continued on page 7)

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pplications Note No. 074

Silicon Discretes

Figure 8. Schematic Diagram of Complete BGA430 + BGB540 LNB I.F. Amplifier

J3

+5.0 Volts

(Total Current Draw = 39.9 mA)

Black Rectangles = Microstriplines on PCB

(PCB Track or Trace)

22.9 mA

17.0 mA

30 ohms

15.45 mA

R6

C6

22 pF

1.55 mA

C2

22 pF

R1

300 ohms

L1

3.0 nH

R4
2K

(R Bias)

J1 J2

RF Input

950 - 2150 MHz

C1

22 pF

IC1

C3

22 pF

R2

18 ohms

R3

300 ohms

C4

1.5 pF

MMIC

Notes:

BGA430

B6HF

Purpose of Pad :

3 dB Pad

1) Gain Reduction (especially at lower end of band)

2) Provide good input termination for HPF

High Pass Filter

Butterworth

= 1860 MHz

f

C (3 dB)

Purpose of HPF :

Adjust overall gain

slope of cascade

43 ohms

L2

4.7 nH

IC2

MMIC

BGB540

B6HFe

R5

C5

22 pF

RF Output

1) Using C4 as both a DC block and as a Highpass Filter element enables the elimination of one capacitor

2) Bias current of Stage 2 (BGB540 MMIC) can be increased or decreased to vary overall output compression point

3) Stage 1 (BGA430) requires careful attention to proper grounding !

Figure 9. Bill Of Material (BOM) for Complete BGA430 + BGB540 LNB I.F. Amplifier

REFERENCE

DESIGNATOR

VALUE

MANUFACTURER

C1, C3, C5 22 pF VARIOUS 0402 DC BLOCK

C2, C6 22 pF VARIOUS 0402 RF BYPASS

C4 1.5 pF VARIOUS 0402 DC BLOCK & HIGH PASS FILTER

L1 3.0 nH MURATA LQP15M 0402 HIGH PASS FILTER FUNCTION
L2 4.7 nH MURATA LQP15M 0402 “RF CHOKE” / DC FEED FOR BGB540,

R1, R3 300 OHMS VARIOUS 0402 FOR 3 dB ATTENUATOR PAD

R2 18 OHMS VARIOUS 0402 FOR 3 dB ATTENUATOR PAD
R4 2K VARIOUS 0402 R

R5 43 OHMS VARIOUS 0402 RF STABILITY AND OUTPUT MATCH FOR

R6 30 OHMS VARIOUS 0402 DROP 5V SUPPLY TO ~ 4.5V. MAY BE

IC1 - INFINEON TECHNOLOGIES SOT363 BGA430 Si MMIC, B6HF PROCESS
IC2 - INFINEON TECHNOLOGIES SOT343 BGB540 ACTIVE BIASED TRANSISTOR

J1, J2 - JOHNSON 142-0701-841 - RF INPUT / OUTPUT CONNECTOR

J3

-

AMP 5 PIN HEADER

MTA-100 SERIES
P/N 640456-5 OR

641215-5 (GOLD PLATING)

CASE SIZE

FUNCTION

FUNCTION

INFLUENCES BGB540 OUTPUT MATCH

FOR IC2 (BGB540 MMIC) - SETS

BIAS

DEVICE CURRENT)

IC2 (BGB540)

OMITTED IF MAXIUM RATINGS OF IC2
ARE NOT EXCEEDED.

MMIC, B6HFe PROCESS

-

DC CONNECTOR
PINS 1, 2, 4, 5 = GROUND
PIN 3 = V

CC

AN 074 Rev E 6 / 24 19-November-2002

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pplications Note No. 074

Silicon Discretes

reverse isolation. Note that all of these results
are taken in a 50 ohm system, and that results in
a 75 ohm system will differ slightly.

Circuit Design Issues Relevant to BGA430:

1) proper device grounding !!

2) proper bypassing of the V

CC

pin !

The BGA430 is an extremely high gain device
(>30 dB @ 1 GHz) contained within a single
SMT package. As a result, casual or sloppy
PCB layout techniques which add undesired
parasitic inductance between BGA430 ground
leads and PCB ground plane will add enough
feedback to adversely alter the BGA430’s gain
and return loss. In cases of extremely poor
grounding, sufficient feedback will be present to
enable either gain “peaking” or even an
oscillation. In addition, the V

pin (Pin 1) needs

CC

to be bypassed with a capacitor that, with its
self-inductance taken into account,
approximates a short-circuit in the 1 to 2 GHz
range. Generally a 0603 or 0402 case-size chip
capacitor in the range of 15 – 22 pF is sufficient.
A photo of a bare I.F. Amp PC board is shown in
Figure 10, with a close-in view of the BGA430
mounting area. Note that seven (7) ground vias
are provided for the BGA430 ground pins,
including three ground vias located immediately
underneath the device. Note the two ground
holes provided for the bypass capacitor C2
(22pF) on the BGA430 V
proximity of C2 to the V

pin, and the close

CC

pin.

CC

To summarize:

• The user must avoid any additional parasitic

ground inductance between BGA430 ground
pins and PCB ground plane. A sufficient
number of ground vias need to be provided
and these vias should be placed as close to
the BGA430 as possible.

• BGA430 V

pin (Pin 1) must be bypassed

CC

carefully, and the bypass capacitor used
must have its “cold” side well-grounded.

If these two suggestions are carefully followed, a
low-cost, single device solution may be used for

some I.F. amplifier designs, requiring only 3
external elements.

Figure 10. BGA430 Mounting Position on PC
Board. Compare unpopulated (above) to
populated (below) PCB images. Note
locations and number of ground vias near
BGA430 MMIC. Pin 1 (V

) is pad at lower left.

CC

It needs to be pointed out that the BGA430 is
designed to operate at a nominal supply voltage
of +5 volts, with a current draw of approximately
23mA. However, if a higher output compression
point is desired, the BGA430 may be safely run
up to 6.5 volts, and maximum safe current is
35mA. If an adjustable output voltage regulator

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pplications Note No. 074

Silicon Discretes

is used in the LNB, and if a higher output power
is required of the BGA430 than is available at
the 5V, 23mA condition, the user has the option
of simply cranking up the BGA430 supply
voltage.

Figure 11. Stand-Alone BGA430 Amp, Input Return Loss.

CH1 S11 log MAG 5 dB/ REF 0 dB

PRm

Cor

Del
Avg
16
Smo

Table 2. Summary of stand-Alone BGA430
LNB I.F. Amplifier Performance.

Conditons: Temperature = 25°C, V = 5.0 Volts, PCB = Infineon
P/N 430-051802 Rev B, Z
power = -40 dBm.

Parameter Frequency, MHz
950 1450 2150
Input Return Loss, dB 11.1 12.2 12.4
Gain, dB 33.4 33.2 27.8
Reverse Isolation, dB 40.5 42.5 46.1
Output Return Loss, dB 13.7 13.4 13.1
Output P

31 Jul 2002 00:56:05

, dBm +3.2 +3.9 +3.2

1dB

2_:-12.193 dB

1 450.000 000 MHz

1_:-11.101 dB

950 MHz

3_:-12.448 dB

2.15 GHz

=50 Ω, network analyzer source

S=ZL

1

START 900.000 000 MHz STOP 2 200.000 000 MHz

2

3

Figure 12. Stand-Alone BGA430 Amp, Input Return Loss, Smith Chart.

Reference Plane = PCB Input SMA Connector.

CH1 S11 1 U FS

PRm

Cor

Del
Avg
16
Smo

2_: 47.119

1

31 Jul 2002 00:56:16

24.293 2.6664 nH
1 450.000 000 MHz

2

3

1_: 29.082

-7.2041
950 MHz

3_: 74.199

-17.477

2.15 GHz

START 900.000 000 MHz STOP 2 200.000 000 MHz

AN 074 Rev E 8 / 24 19-November-2002