BGA430 datasheet(2/24 Pages) INFINEON

2 / 24 page

AN 074 Rev E

2 / 24

19-November-2002

Applications 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 cost-

effective 25 GHz transition frequency (fT) B6HF

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

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 fT B6Hfe

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 4-

pin 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 “ RBIAS “ – required for a given

device current can be determined from curves

given in the BGB540 datasheet.

For lower

operating currents, the value of RBIAS becomes

large, and therefore RBIAS in series with the

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).

Figure 2. BGB540 Block Diagram and

Package (SOT343).

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

Base

Pin 1

1/10 BFP540

BFP540

Bias

Pin 4

Pin 3

Emitter

Pin 2

BGB 540 B6HFe

CE MAX = 4.5 V

C MAX = 80 mA

GND1

GND2

RFin

GND1

RFout

Vcc

Bias

BGA430 (B6HF) V

MAX = 6.5 V,

MAX = 35 mA

BGA430 датащи(PDF) 2 Page - Infineon Technologies AG

BGA430 датащи(HTML) 2 Page - Infineon Technologies AG

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

датащи скачать

ссылки URL