User manual PHILIPS BLF574

[. . . ] 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 MHz to 108 MHz band in a space smaller than 50. 8 mm × 101. 6 mm (2 " × 4 "). The circuit only needs to be 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. 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. AN10714_1 © NXP B. V. [. . . ] 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 of the circuit have the most impact on the circuit operating frequency and PL(1dB) performance. The modification areas 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 trade-off between efficiency and linearity. 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. 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 PL(1dB) is seen when the characteristic impedance of these transformers is changed. Effect of changing the output capacitor (C14): · Changing this output capacitor has an effect of tilting the response over the band. The efficiency or PL(1dB) performance can be made more consistent over the band by modifying C14. Effect of adding capacitance off the drain (C10, C11, C15, and C16): · A small adjustment in the trade-off between efficiency and PL(1dB) performance can be made by changing these capacitors. AN10714_1 © NXP B. V. 01 -- 26 January 2010 10 of 21 NXP Semiconductors AN10714 Using the BLF574 in the 88 MHz to 108 MHz FM band 4. 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 Th = 25 °C. 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 can be used to get the first-pass matching circuits. Table 3. Input and output impedance per section Input (Zi) 2. 020 - j26. 216 2. 020 - j13. 087 2. 020 - j8. 701 2. 020 - j6. 500 2. 021 - j5. 175 2. 021 - j4. 286 2. 022 - j3. 647 2. 023 - j3. 164 2. 023 - j2. 768 2. 024 - j2. 480 2. 025 - j2. 227 2. 026 - j2. 014 2. 028 - j1. 832 2. 029 - j1. 673 2. 030 - j1. 534 2. 032 - j1. 410 2. 033 - j1. 299 2. 035 - j1. 199 2. 037 - j1. 108 2. 039 - j1. 025 Output (Zo) 4. 987 - j0. 241 4. 947 - j0. 477 4. 882 - j0. 705 4. 794 - j0. 922 4. 685 - j1. 125 4. 559 - j1. 310 4. 418 - j1. 478 4. 266 - j1. 626 4. 106 - j1. 755 3. 941 - j1. 864 3. 773 - j1. 955 3. 605 - j2. 028 3. 439 - j2. 084 3. 275 - j2. 126 3. 116 - j2. 154 2. 962 - j2. 170 2. 814 - j2. 176 2. 673 - j2. 172 2. 538 - j2. 159 2. 410 - j2. 140 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 500 Frequency (MHz) The convention for these impedances is shown in Figure 10. They indicate the impedances looking into half the device. Zo Zi 001aak541 Fig 10. 01 -- 26 January 2010 14 of 21 NXP Semiconductors AN10714 Using the BLF574 in the 88 MHz to 108 MHz FM band 6. Base plate drawings 6. 1 Input base plate P O F E M Q (2×) D C N (2×) (4×) B A A G HI A K L A engraved letter "M" J Unit mm A 0 B C D E F G H I J K L M 9 N M2 10. 922 37. 211 45. 847 65. 278 76. 200 6. 350 9. 068 12. 573 71. 120 3. 505 6. 223 Unit mm O 8 P 44. 32 Q 5. 6 001aak566 Fig 11. [. . . ] 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. 11. 3 Trademarks Notice: All referenced brands, product names, service names and trademarks are the property of their respective owners. AN10714_1 © NXP B. V. 01 -- 26 January 2010 20 of 21 NXP Semiconductors AN10714 Using the BLF574 in the 88 MHz to 108 MHz FM band 12. 11 Output gain and efficiency variation under different drain voltage conditions . [. . . ]