Philips AN10714 Application note

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AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

Rev. 01 — 26 January 2010 Application note

Document information

Info Content Keywords BLF574, 600 MHz performance, high voltage LDMOS, amplifier

implementation, Class-B CW, FM band, pulsed power

Abstract This application note describes the design and the performance of the

BLF574 for Class-B CW and FM type applications in the 88 MHz to 108 MHz frequency range.

NXP Semiconductors

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

Revision history

Rev Date Description

01 20100126 Initial version

Application note Rev. 01 — 26 January 2010 2 of 21

NXP Semiconductors

1. Introduction

The BLF574 is a new, 50 V, push-pull transistor using NXP Semiconductors’ 6th generation of high voltage LDMOS technology. The two push-pull sections of the device are completely independent of each other inside the package. The gates of the device are internally protected by the integrated ElectroStatic Discharge (ESD) diode.

The device is unmatched and is designed for use in applications below 600 MHz where very high power and efficiency are required. Typical applications are FM/VHF broadcast, laser or Industrial Scientific and Medical (ISM) applications.

Great care has been taken during the design of the high voltage process to ensure that the device achieves high ruggedness. This is a critical parameter for successful broadcast operations. The device can withstand greater than a 10 full operating power.

Another design goal was to minimize the size of the application circuit. This is important in that it allows amplifier designers to maximize the power in a given amplifier size. The design highlighted in this application note achieves over 600 W in the 88 band in a space smaller than 50.8 as wide as the transistor itself, enabling transistor mounting in the final amplifier to be as close as physically possible while still providing adequate room for the circuit implementation.

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

: 1 VSWR for all phase angles at

MHz to 108 MHz

mm × 101.6 mm (2 ” × 4 ”). The circuit only needs to be

This application note describes the design and the performance of the BLF574 for Class-B CW and FM type applications in the 88

MHz to 108 MHz frequency band.

Application note Rev. 01 — 26 January 2010 3 of 21

NXP Semiconductors

2. Circuit diagrams and PCB layout

2.1 Circuit diagrams

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

C27

C26C25

RF in

V bias in

R12

L22

R8 R3

C6 C5

R15 R14 R10

R11

R16

L10

L24

C30

C29C28

R13

L11

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Fig 1. BLF574 input circuit schematic; 88 MHz to 108 MHz

Application note Rev. 01 — 26 January 2010 4 of 21

NXP Semiconductors

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

C17 C18 C19 C20

L14

L25

L15

C21

C12

L23

C31

C32

C33

C34

L12

C13

C22 C23

L16

L17

C24

C15

C16

C10

L12

L13

C11

Fig 2. BLF574 output circuit schematic; 88 MHz to 108 MHz

C14

L19

L20

RF out

L21

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Application note Rev. 01 — 26 January 2010 5 of 21

Application note Rev. 01 — 26 January 2010 6 of 21

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NXP Semiconductors

2.2 BLF574 PCB layout

C20

C25

D1C6R8 C5

L22

R9 C7

BLF574

input-rev 3

30RF35

C26

R10R12 C29

C27

R11

C28

C30

R13

R16

L14

L10

L24

L11

R15

R14

C10 C15

L12

L13

C16 C11

L15

BLF574

output-rev 3

30RF35

L23

C12

L16

C13

C31

C32

C33

C34

L17

L18

C17 C18 C19

C14

C21 C22 C23

L19

L20

L21

Using the BLF574 in the 88 MHz to 108 MHz FM band

C24

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AN10714

The positions of C1, C19 and C23 are indicated but these capacitors are not connected.

Fig 3. BLF574 PCB layout

NXP Semiconductors

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

2.3 Bill Of Materials

Table 1. Bill of materials for the BLF574 input and output circuits

PCB material: Taconic RF35;

Designator Description Part number Manufacturer

B1 63.5 mm (2.5 ”)/50 Ω semirigid through

B2 coax cable; 124.5 mm (4.9 ”)/50 Ω;

C1 not connected - C2, C3 4700 pF ceramic chip capacitor ATC700B472KW50X American Technical Ceramics C4, C7, C26, C29 1 μF ceramic chip capacitor GRM31MR71H105KA88L MuRata C5, C6, C9 100 nF ceramic chip capacitor GRM21BR71H104KA01L MuRata C8 620 pF ceramic chip capacitor ATC100B621JT100X American Technical Ceramics C10, C11 390 pF ceramic chip capacitor ATC100B220GT500X American Technical Ceramics C12, C13 180 pF ceramic chip capacitor ATC100B181JT200X American Technical Ceramics C14 6.8 pF ceramic chip capacitor ATC100B6R8CT500X American Technical Ceramics C15, C16 15 pF ceramic chip capacitor ATC100B150JT500X American Technical Ceramics C17, C21, C31, C32 100 nF/250 V ceramic chip capacitor GRM32DR72E104KW01L MuRata C18, C22, C33, C34 2.2 μF/100 V ceramic chip capacitor GRM32ER72A225KA35 MuRata C19, C23 not connected - C20, C24 1000 μF, 100 V electrolytic capacitor EEV-TG1V102M Panasonic C25, C28 10 nF/35 V ceramic chip capacitor GRM32ER7YA106KA12L MuRata C27, C30 100 nF ceramic chip capacitor GRM31CR72E104KW03L MuRata D1 LED APT2012CGCK KingBright L1 21.7 mm × 1.75 mm (855 mil × 69 mil) - L2 9.2 mm × 1.65 mm (364 mil × 65 mil) - L3 9.9 mm × 1.75 mm (390 mil × 69 mil) - L4, L5 6.2 mm × 5.5 mm (243 mil × 218 mil) - L6, L7 L8, L9 5.2 mm × 5.54 mm (205 mil × 218 mil) - L10, L11 13.0 mm × 13.2 mm (511 mil × 520 mil) - L12, L13 8.8 mm × 13.2 mm (345 mil × 520 mil) - L14, L15 8.83 mm × 3.81 mm (348 mil × 150 mil) - L16, L17 L18, L23 3 turns 14 gauge wire;

L19 21.2 mm × 1.75 mm (834 mil × 69 mil) - L20 9.5 mm × 1.82 mm (373 mil × 72 mil) - L21 13.99 mm × 1.7 mm (551 mil × 65 mil) - L22 ferroxcube bead 2743019447 Fair Rite L24 50.8 mm (2 ”); 14 gauge wire;

L25 7.6 mm × 15.3 mm (299 mil × 604 mil) - -

= 3.5; thickness 0.76 mm (30 mil). Figure 3 shows the BLF574 PCB layout.

[1]

ferrite

ID = 3.5814 mm (0.141 ")

[2]

ID = 7.9 mm (0.310 ”)

ID = 15.5 mm (0.61 ”)

[3]

ferrite: BN-61-202 Amidon semirigid: 047-50 Micro-Coax UT-141C-Form-F Micro-Coax

- -

Application note Rev. 01 — 26 January 2010 7 of 21

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Using the BLF574 in the 88 MHz to 108 MHz FM band

Table 1. Bill of materials for the BLF574 input and output circuits …continued

PCB material: Taconic RF35;

Designator Description Part number Manufacturer

Q1 7808 voltage regulator NJM#78L08UA-ND NJR Q2 SMT 2222 NPN transistor PMBT2222 NXP Semiconductors Q3 600 W LDMOST BLF574 NXP Semiconductors R1 200 Ω potentiometer 3214W-1-201E Bourns R2, R3 432 Ω resistor CRCW0805432RFKEA Vishay Dale R4 2 kΩ resistor CRCW08052K00FKTA Vishay Dale R5 75 Ω resistor CRCW080575R0FKTA Vishay Dale R6 not connected - R7, R9 1.1 kΩ resistor CRCW08051K10FKEA Vishay Dale R10 11 kΩ resistor CRCW080511K0FKEA Vishay Dale R11 5.1 Ω resistor CRCW08055R1FKEA Vishay Dale R12 499 Ω/0.25 W resistor CRCW2010499RFKEF Vishay Dale R13, R16 9.1 Ω resistor CRCW08059R09FKEA Vishay Dale R14 5.1 kΩ resistor CRCW08055K10FKTA Vishay Dale R15 910 Ω resistor CRCW0805909RFKTA Vishay Dale T1, T2 63.5 mm (2.5 ”)/25 Ω semirigid through

T3, T4 coax cable 86.36 mm (3.4 ”)/25 Ω;

= 3.5; thickness 0.76 mm (30 mil). Figure 3 shows the BLF574 PCB layout.

[1]

ferrite

ID = 2.18 mm (0.086 ")

ferrite: BN-61-202 Amidon semirigid: 047-25 Micro-Coax E22[1]STJ Thermax

[1] The semirigid cable length is defined in Figure 4. [2] Contact your local NXP Semiconductors sales person for the artwork file containing the dimensions. [3] N-male connector mounted as close to the package as possible.

semirigid cable length

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Fig 4. Cable length definition

Application note Rev. 01 — 26 January 2010 8 of 21

NXP Semiconductors

2.4 PCB form factor

Care has been taken to minimize board space for the desig n. Figure 5 shows how 600 W can be generated in a space only as wide as the transistor itself.

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

Fig 5. Photograph of the BLF574 circuit board

3. Amplifier design

3.1 Mounting considerations

To ensure good thermal cont act, a heatsink compo und (such as Dow Corning 340) shou ld be used when mounting the BLF574 in the SOT539A package to the heatsink. Improved thermal contact is obtainable when the devices are soldered on to the heatsink. This lowers the junction temperature at high operating power and results in slightly better performance.

When greasing the part down, care must be taken to ensure that the amount of grease is kept to an absolute minimum. The NXP Semiconductors’ website can be consulted for application notes on the recommended mounting procedure for this type of device or from your local NXP salesperson.

3.2 Bias circuit

A temperature compensated bias circuit is used and comprises the following: An 8 V voltage regulator (Q1) supplies the bias circui t. The temper ature sensor (Q2) must

be mounted in good thermal contact with the device under test (Q3). The quiescent current is set using a potentiometer (R1). The gate voltage correction is approximately

−4.8 mV/°C to −5.0 mV/°C. The V

range is also reduced using a resistor (R2).

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Application note Rev. 01 — 26 January 2010 9 of 21

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The −2.2 mV/°C at its base is generated by Q2. This is then multiplied by the R14 : R15 ratio for a temperature slope (i.e. approximately −15 provided by the transistor is the reason it is used rather than a diode. A portion of the

−15 The amount of temperature compensation is set by resistor R4. The ideal value of which

proved to be 2 compensation. However, they are used for baseband stability and to improve IMD asymmetry at lower power levels.

3.3 Amplifier alignment

There are several points in the circuit that allow performance parameters to be readily traded off against one another. In general, the following areas o f th e circu it h ave th e m ost impact on the circuit operating frequency and P are listed in order of sensitivity, with the most sensitive tuning elements listed first.

Effect of changing the output capacitors (C12 and C13):

• This is a key tuning point in the circuit. This point has the strongest influence on the

Using the BLF574 in the 88 MHz to 108 MHz FM band

mV/°C is applied to the potentiometer (R1).

kΩ. The values of R11 and R13 are not important for temperature

trade-off between efficiency and linearity.

AN10714

mV/°C). The multiplication function

performance. The modification areas

L(1dB)

Effect of the length of the output balun (B2):

• The frequency can be shifted by modifying this element. Typically, the longer the

balun, the more the response is shifted to lower frequencies. Conversely, a short balun shifts the response to higher frequencies.

Effect of changing the output 4 : 1 transformers (T3 and T4):

• The frequency can be shifted by modifying these elements. In general, longer

transformers shift the whole response to a lower frequency. Shortening the transformers shifts the response to higher frequencies. Changes in efficiency and P

is seen when the characteristic impedance of these transformers is changed.

L(1dB)

Effect of changing the output capacit or (C14):

• Changing this output capacitor has an ef fect of tilting the respo nse over the band. The

efficiency or P modifying C14.

Effect of adding capacitance off the drain (C10, C11 , C15, and C16):

• A small adjustment in the trade-off between ef ficiency and P

made by changing these capacitors.

performance can be made more consistent over the band by

L(1dB)

performance can be

L(1dB)

Application note Rev. 01 — 26 January 2010 10 of 21

NXP Semiconductors

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4. RF performance characteristics

4.1 Continuous wave

T able 2. Class-B performance of the BLF574 at 50 V/600 W

This table summarizes the Class-B performance of the BLF574 at 50 V, IDq = 200 mA and

= 25 °C.

Frequency (MHz) PL (W) Gp (dB) η (%) RL (dB)

88 600 24.8 73.3 7.5 98 600 25.3 73.5 9 108 600 25.6 71.9 11.5

4.2 Continuous wave graphics

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

(dB)

0 800600400200

(1) (2) (3)

PL (W)

(%)

VDD = 50 V; IDq = 200 mA. (1) 88 MHz. (2) 98 MHz. (3) 108 MHz.

Fig 6. Typical CW data; 88 MHz to 108 MHz

Figure 7 shows the difference in gain and efficiency depen ding on the drain voltage

conditions.

Application note Rev. 01 — 26 January 2010 11 of 21

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001aal309

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Using the BLF574 in the 88 MHz to 108 MHz FM band

(dB)

0 800600400200

(1) (2) (3) (4)

PL (W)

(%)

BLF574 at 98 MHz, IDq = 200 mA. (1) 46 V. (2) 48 V. (3) 50 V. (4) 52 V.

Fig 7. Output gain and efficiency variation under different drain voltage conditions

Figure 8 compares the performance of Class-B and Class-AB amplifier configurations.

(dB)

0 800600400200

BLF574 at 98 MHz, VDD = 50 V.

(1) (2)

PL (W)

(1) 200 mA. (2) 1 A.

Fig 8. Output gain and efficiency comparison for Class-B and Class-AB amplifiers

Figure 9 shows the second order harmonic performance.

(%)

Application note Rev. 01 — 26 January 2010 12 of 21

NXP Semiconductors

001aal310

Fig 9. Second order harmonics as a function of output power against frequency

−20

(dBc)

−30

−40

−50

0 800600400200

VDD = 50 V; IDq = 200 mA. (1) 88 MHz. (2) 98 MHz. (3) 108 MHz.

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

(1)

(2)

(3)

PL (W)

Application note Rev. 01 — 26 January 2010 13 of 21

NXP Semiconductors

5. Input and output impedance

The BLF574 input and output impedances are given in Table 3. These are generated from a first order equivalent circuit of the device and ca n be u sed to get the first-pass matching circuits.

Table 3. Input and output impedance per section

Frequency (MHz) Input (Zi) Output (Zo)

25 2.020 − j26.216 4.987 − j0.241 50 2.020 − j13.087 4.947 − j0.477

75 2.020 − j8.701 4.882 − j0.705 100 2.020 − j6.500 4.794 − j0.922 125 2.021 − j5.175 4.685 − j1.125 150 2.021 − j4.286 4.559 − j1.310 175 2.022 − j3.647 4.418 − j1.478 200 2.023 − j3.164 4.266 − j1.626 225 2.023 − j2.768 4.106 − j1.755 250 2.024 − j2.480 3.941 − j1.864 275 2.025 − j2.227 3.773 − j1.955 300 2.026 − j2.014 3.605 − j2.028 325 2.028 − j1.832 3.439 − j2.084 350 2.029 − j1.673 3.275 − j2.126 375 2.030 − j1.534 3.116 − j2.154 400 2.032 − j1.410 2.962 − j2.170 425 2.033 − j1.299 2.814 − j2.176 450 2.035 − j1.199 2.673 − j2.172 475 2.037 − j1.108 2.538 − j2.159 500 2.039 − j1.025 2.410 − j2.140

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

The convention for these impedances is shown in Figure 10. They indicate the impedances looking into half the device.

Fig 10. Device impedance convention

Application note Rev. 01 — 26 January 2010 14 of 21

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6. Base plate drawings

6.1 Input base plate

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

UnitmmA0B

10.922C37.211D45.847E65.278F76.200G6.350H9.068I12.573J71.120

Unit

O8P

44.32Q5.6

(2×)

engraved letter "M"

(2×)

(4×)

AKLH

3.505L6.223M9NM2

001aak56

Fig 11. Input base plate drawing

Application note Rev. 01 — 26 January 2010 15 of 21

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6.2 Device insert

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

(2×)

engraved letter "M"

(2×)

HG A IA E

UnitmmA0B

10.922C65.278D76.200E6.350F11.328G5.156H10.312I4.978J11.328K10.185L1.143M8NM5

Unit O

72.644P59.309Q23.749

3.556S3.5TM2.5

(1) +0.5 mm.

Fig 12. Device insert drawing

(1)

0.254V10.058

001aak56

Application note Rev. 01 — 26 January 2010 16 of 21

NXP Semiconductors

6.3 Output base plate

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

UnitmmA

0B10.922C37.211D45.847E65.278F76.200G6.350H9.068I12.573J71.120

Unit

N8O

(2×)

engraved letter "M"

(4×)

3.505LM5MM2

001aak56

Fig 13. Output base plate drawing

7. Reliability

Time-to-Failure (TTF) is defined as the expected time elap sed until 0.1 % of the devices of a sample size fail. This is different from Mean-Time-to-Failure (MTBF), where half the devices would have failed and is orders of magnitude are shorter. The predominant failure mode for LDMOS devices is electromigration. The TTF for this mode is primarily dependant on junction temperature (T device junction temperature is measured and in-depth knowledge is obt ained of the average operating current for the application, the TTF can be calculated using and the related procedure.

7.1 Calculating TTF

The first step uses the thermal resistance (Rth) of the device to calculate the junction temperature. The R the device is soldered down to the heat sink, this same value can be used to determine T If the device is greased down to the heatsink, the R

Application note Rev. 01 — 26 January 2010 17 of 21

from the junction to the device flange for the BLF574 is 0.25 °C/W . If

) added to the effect of current density. Once the

Figure 14

value becomes 0.4 °C/W.

th(j-h)

NXP Semiconductors

Example: Assuming the device is running at 600 W with the RF output power at 70 %

efficiency on a heatsink (e.g. 40 °C). T efficiency for the given heatsink temperature:

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

can be determined based on the operating

• Dissipated power (P

• Temperature rise (T

• Junction temperature (T

) = 257 W

) = Pd × Rth = 257 W × (0.4 °C/W) = 103 °C

) = Th + Tr = 40 °C + 103 °C = 143 °C

Based on this, the TTF can be estimated using a device greased-down heatsink as follows:

• The operating current is just above 17 A

• T

= 140 °C

The curve in Figure 14 intersects the x-axis at 17 A. At this point, it can be estimated that it would take 100 years for 0.1 % of the devices to fail.

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TTF

(y)

(1)

(2)

(3) (4) (5) (6) (7) (8)

(9) (10) (11)

0 20168124

(1) Tj = 100 °C. (2) Tj = 110 °C. (3) Tj = 120 °C. (4) Tj = 130 °C. (5) Tj = 140 °C. (6) Tj = 150 °C. (7) Tj = 160 °C. (8) Tj = 170 °C.

(9) Tj = 180 °C. (10) Tj = 190 °C. (11) Tj = 200 °C.

(A)

Fig 14. BLF574 time-to-failure

Application note Rev. 01 — 26 January 2010 18 of 21

NXP Semiconductors

8. Test configuration block diagram

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

SIGNAL

GENERATOR

E4437B

SPINNER

SWITCH

DRIVER

AMPLIFIER

Ophir 5127

Fig 15. BLF574 test configuration

9. PCB layout diagrams

NETWORK ANALYZER

HP8753D

10 30 10

COUPLER

HP778D

ANZAC

CH132

DUT

POWER

METER

E4419B

POWER

SENSOR

HP8481A

TENULINE

30 dB

1 kW

SPECTRUM

ANALYZER

Rhode & Schwarz

FSEB

NARDA

3020A

10 dB

PA D

ANZAC

CH132

RF LOW PASS

FILTER

POWER

SENSOR

HP8481A

001aal31

Please contact your local NXP Semiconductors’ salesperson for copies of the PCB layout files.

10. Abbreviations

Table 4. Abbreviations

Acronym Description

CW Continuous Wave ESD ElectroStatic Discharge FM Frequency Modulation IMD InterModulation Distortion IRL Input Return Loss LDMOST Laterally Diffused Metal-Oxide Semiconductor Transistor PAR Peak-to-Average power Ratio PCB Printed-Circuit Board SMT Surface Mount Technology VHF Very High Frequency VSWR Voltage Standing Wave Ratio

Application note Rev. 01 — 26 January 2010 19 of 21

NXP Semiconductors

11. Legal information

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

11.1 Definitions

Draft — The document is a draft version only. The content is still under

internal review and subject to formal approval, which may result in modifications or additions. NXP Semiconductors does not give any representations or warranties as to the accuracy or completeness of information included herein and shall have no liability for the consequences of use of such information.

11.2 Disclaimers

General — Information in this document is believed to be accurate and

reliable. However, NXP Semiconduct ors does not give any repr esentatio ns or warranties, expressed or implied, as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information.

Right to make changes — NXP Semiconductors reserves the right to make changes to information published in this document, including without limitation specifications and product descriptions, at any time and without notice. This document supersedes and replaces all information supplied prior to the publication hereof.

Suitability for use — NXP Semiconductors products are not designed, authorized or warranted to be suitable for use in medical, military, aircraft, space or life support equipment, nor in applications where failure or malfunction of an NXP Semiconductors product can reasonabl y be expected to result in personal injury, death or severe property or environmental damage. NXP Semiconductors accepts no liability for inclusion and/or use of NXP Semiconductors products in such equipment or applications and therefore such inclusion and/or use is at the customer’s own risk.

Applications — Applications that are described herein for any of these products are for illustrative purposes only. NXP Semiconductors makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification.

Export control — This document as well as the item(s) described herein may be subject to export control regulations. Export might require a prior authorization from national authorities.

11.3 Trademarks

Notice: All referenced brands, prod uct names, service names and trad emarks are the property of their respective owners.

Application note Rev. 01 — 26 January 2010 20 of 21

NXP Semiconductors

12. Figures

AN10714

Using the BLF574 in the 88 MHz to 108 MHz FM band

Fig 1. BLF574 input circuit schematic;

88 MHz to 108 MHz. . . . . . . . . . . . . . . . . . . . . . . .4

Fig 2. BLF574 outp ut circuit schematic;

88 MHz to 108 MHz. . . . . . . . . . . . . . . . . . . . . . . .5

Fig 3. BLF574 PCB layout . . . . . . . . . . . . . . . . . . . . . . . .6

Fig 4. Cable length definition . . . . . . . . . . . . . . . . . . . . . .8

Fig 5. Photograph of the BLF57 4 circuit board . . . . . . . .9

Fig 6. Typical CW data; 88 MHz to 108 MHz. . . . . . . . .11

Fig 7. Outp ut gain and efficiency variation under

different drain voltage conditions. . . . . . . . . . . . .12

13. Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Circuit diagrams and PCB layout. . . . . . . . . . . 4

2.1 Circuit diagrams . . . . . . . . . . . . . . . . . . . . . . . . 4

2.2 BLF574 PCB layout . . . . . . . . . . . . . . . . . . . . . 6

2.3 Bill Of Materials . . . . . . . . . . . . . . . . . . . . . . . . 7

2.4 PCB form factor . . . . . . . . . . . . . . . . . . . . . . . . 9

3 Amplifier design. . . . . . . . . . . . . . . . . . . . . . . . . 9

3.1 Mounting considerations. . . . . . . . . . . . . . . . . . 9

3.2 Bias circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.3 Amplifier alignment . . . . . . . . . . . . . . . . . . . . . 10

4 RF performance characteristics. . . . . . . . . . . 11

4.1 Continuous wave . . . . . . . . . . . . . . . . . . . . . . 11

4.2 Continuous wave graphics . . . . . . . . . . . . . . . 11

5 Input and output impedance. . . . . . . . . . . . . . 14

6 Base plate drawings . . . . . . . . . . . . . . . . . . . . 15

6.1 Input base plate . . . . . . . . . . . . . . . . . . . . . . . 15

6.2 Device insert. . . . . . . . . . . . . . . . . . . . . . . . . . 16

6.3 Output base plate . . . . . . . . . . . . . . . . . . . . . . 17

7 Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

7.1 Calculating TTF . . . . . . . . . . . . . . . . . . . . . . . 17

8 Test configuration block diagram . . . . . . . . . 19

9 PCB layout diagrams. . . . . . . . . . . . . . . . . . . . 19

10 Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . 19

11 Legal information. . . . . . . . . . . . . . . . . . . . . . . 20

11.1 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

11.2 Disclaimers. . . . . . . . . . . . . . . . . . . . . . . . . . . 20

11.3 Trademarks. . . . . . . . . . . . . . . . . . . . . . . . . . . 20

12 Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

13 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Fig 8. Output gain and efficiency comparison for

Class-B and Class-AB amplifiers . . . . . . . . . . . . 12

Fig 9. Second order harmonics as a function of

output power against frequency . . . . . . . . . . . . . 13

Fig 10. Device impedance convention . . . . . . . . . . . . . .14

Fig 11. Input base plate drawing. . . . . . . . . . . . . . . . . . .15

Fig 12. Device insert drawing . . . . . . . . . . . . . . . . . . . . .16

Fig 13. Output base plate drawing . . . . . . . . . . . . . . . . . 17

Fig 14. BLF574 time-to-failure. . . . . . . . . . . . . . . . . . . . . 18

Fig 15. BLF574 test configuration. . . . . . . . . . . . . . . . . . 19

Please be aware that important notices concerning this document and the product(s) described herein, have been included in section ‘Legal information’.

For more information, please visit: http://www.nxp.com For sales office addresses, please send an email to: salesaddresses@nxp.com

Date of release: 26 January 2010

Document identifier: AN10714_1

Philips AN10714 Application note

Specifications and Main Features

Frequently Asked Questions

User Manual

1. Introduction

2. Circuit diagrams and PCB layout

2.1 Circuit diagrams

2.2 BLF574 PCB layout

2.3 Bill Of Materials

2.4 PCB form factor

3. Amplifier design

3.1 Mounting considerations

3.2 Bias circuit

3.3 Amplifier alignment

4. RF performance characteristics

4.1 Continuous wave

4.2 Continuous wave graphics

5. Input and output impedance

6. Base plate drawings

6.1 Input base plate

6.2 Device insert

6.3 Output base plate

7. Reliability

7.1 Calculating TTF

8. Test configuration block diagram

9. PCB layout diagrams

10. Abbreviations

11. Legal information

11.1 Definitions

11.2 Disclaimers

11.3 Trademarks

12. Figures

13. Contents