Application Note 5499

Transcription

1 MGA and MGA High-Gain Driver Amplifier Using Avago MGA and MGA Application Note 5499 Introduction The MGA and MGA from Avago Technologies are.1 Watt flat-gain driver amplifier monolithic microwave integrated circuits (MMICs). These devices feature broadband inputs and outputs pre-matched at 5 Ω, making them easy to use. Operating on a single +5 V supply, they deliver a flat gain of +/-.2 db across a frequency bandwidth of +/- 1 MHz exceptional high-gain and high-linearity performance. These amplifiers exhibit good input and output return losses and low noise figure (NF) performance. The MGA is the proper amplifier for applications ranging from 25 MHz to 1.5 GHz application, while the MGA best serves the 1.5 GHz to 3 GHz range. Table 1 below provides a summary of the performance figures extracted from the data sheets. Measured performance at each frequency in this table corresponds to a specific application circuit and bill of material in the datasheet. These products provide a nominal gain of more than 19 db, and input return loss (IRL) and output return loss (ORL) greater than 1 db. Both products exhibit high OIP3 (>+37 dbm), making them suitable for use as a driver amplifier in the transmit chain or as a second-stage LNA in the receiver chain. Table 1. MGA-31X89 series performance summary Low Band Product High Band Product Symbol Unit MGA (25 MHz to 1.5 GHz) MGA (1.5 GHz to 3 GHz) Frequency MHz Vdd V Idd ma Gain db IRL db ORL db OIP3 dbm OP1dB dbm NF db

2 MGA and MGA Product Overview The MGA-31X89 product line uses Avago Technologies proprietary.25 μm GaAs Enhancement mode PHEMT process. MGA-31X89 is housed in a three-lead (SOT-89) surface mount plastic package with the dimensions of 4.5 x 2.5 x 1.5 mm. The footprint and pin configuration are shown in Figure 1. Output GND GND Input Figure 1. MGA-31X89 SOT-89 package and pin connections MGA-31X89 Demonstration Board a) Demonstration Board Layout Since both the input and output ports of MGA-31X89 devices are pre-matched at 5 Ω, a 5 Ω transmission line on demonstration board is essential to minimize the loss and maximize power transfer. Proper transmission line design is important for a successful amplifier design. In this design, all micro-strip sections use a 1-mil-thick PCB layer of RO435 dielectric material. The board has a coplanar waveguide (CPWG) transmission line with a characteristic impedance of 5 Ω at a 9 MHz design frequency. The CPWG dimensions are easily calculated using the free AppCad simulation software available from Avago ( The AppCad CPWG design screen is shown in Figure 2 below. Table 2 shows the pin configuration and description for both MGA-31X89 devices. MGA products are very easy to use. For most applications, all that is required is to apply +5 V DC to the RF output pin and the device should draw a current of 6 ma to 9 ma. The RF input and RF output ports are closely matched to 5 Ω impedance, thereby minimizing the need for external matching components in the application circuit. Table 2. MGA-31X89 pin configuration Pin Label Description Input RF In RF Input of the device Output RF Out and Vdd RF Output of the device Voltage supply for the device GND GND Grounding for the device Figure 2. App CAD Calculator for coplanar waveguide design 2

3 b) Demonstration Board Materials This demonstration board is a three-layer board with a 1-mil-thick top layer and a 52-mil thick bottom layer. The first layer uses Rogers RO435 material with a dielectric constant of 3.48, while the second layer consists of FR4 with a dielectric constant of 4.2 which provides better mechanical rigidity. The stacking structure of the PCB is illustrated in Figure 3. The total thickness of the board is about 62 mils, allowing SMA connectors (EF Johnson ) to be easily slipped in at the edges. DC pin headers are soldered at the top edge of the top layer of the board. Figure 4 shows the top layer and bottom layer of the MGA-31X89 series demonstration board. c) PCB Grounding The demonstration board uses plated through holes (vias) to bring the ground to the top side of the circuit where needed. Multiple vias are used to reduce the inductance of the path to ground. Via (1 mils) Total Thickness 62 mils RO435 (1 mils) FR4 (52 mils) Copper Layer (.5 oz) Figure 3. Stacking Structure for MGA-31X89 Demonstration Board Top View Figure 4. Top view and bottom view of the demonstration board Bottom View 3

4 MGA-31X89 Application Circuit V dd = 5 V (Optional) C3 C2 C1 L1 RFin C4 Pin 3 RFout Pin 1 V d C5 L2 (Optional) Pin 2 (GND) L3 (Optional) Figure 5. MGA-31X89 application circuit Figure 5 shows the basic application circuit for MGA-31X89 to function as amplifier. This application circuit includes blocking capacitors on the input and output including RF chokes at the output and bypass capacitors along the voltage supply line at the output pin. In this application note, two types of output matching will be discussed in detail, specifically Best Output IP3 and Best Output RL. The input match for both of the application circuits remains unchanged because the input impedance location is very close to 5 Ω. So only a coupling capacitor C4 with a low reactance relative to 5 Ω at the lowest operating frequency is needed as input matching network. For a 9 MHz application circuit, the calculation to determine the value for C4 is shown below: The formula for the impedance of an input capacitor is defined as: X C = 1 / jωc, where ω = 2πf = 1 / (j x 2π x 9 x 1 6 x C) Assume X C =.2 Ω (Short at 9 MHz) C4 = 1 / (2π x 9 x 1 6 x.2) = 88 pf (1 pf was chosen for C1 and C2 at 9 MHz) The bypass capacitors C1, C2 and C3 help to eliminate the out-of-band low-frequency signals from the power supply. For output match, inductor L1 and a coupling capacitor C5 are required to match the output impedance for either Best OIP3 performance of performance. A detailed discussion follows: 4

5 a) Matching for Best OIP3 Performance For Best OIP3 matching, L1 and C5 are chosen based on the Gamma Input and Output data which is available from the data sheet. Inductor L1 and capacitor C5 are essential to steer the output impedance towards the impedance location that provides the Best OIP3 performance. The input and output were tuned to Gamma locations derived from the data sheet for 45 MHz, 9 MHz and 15 MHz for MGA and 19 MHz and 25 MHz for MGA to give the Best Output IP3 performance. Table 3 shows the input and output impedance location to achieve the Best OIP3 performance. The bill of material for this matching is available in table 4 and 5. Figure 6a shows the Gamma Input and Gamma Output location for Best OIP3 performance at 9 MHz application circuit. Table 3. Gamma Input and Output Matching for Best OIP3 performance b) Matching for Best Output RL Performance For Best Output RL, a conjugate match output will give a very good output return loss (ORL). As shown in Figure 6b (left impedance circle) below, for a 9 MHz application circuit, a shunt inductor followed by a series capacitor is needed to move the S22 impedance towards the 5 Ω match point. The right impedance circle shows the output impedance location, which is close to 5 Ω impedance after the conjugate match method is applied. This matching provides a good Output RL of >18 db at 9 MHz, resulting in a minimum reflected power at the output port. This approach will be used for the rest of the frequencies (i.e., 9 MHz, 15 MHz and 19 MHz). For 45 MHz and 25 MHz, an additional L3 shunt inductor is required to move the output impedance to the 5 Ω location. Γ Input Γ Output Part Number Freq (MHz) Magnitude Angle Magnitude Angle MGA MGA MGA MGA MGA Output Matching for Gamma Location Input Matching for Gamma Location Figure 6a. Input Gamma and Output Gamma location for MGA at 9 MHz application Series Capacitor Shunt Inductor m1 MGA31389_S2P_Verify_9MHz..S(2,2) Moving towards the 5 point for 9 MHz m2 freq (5. MHz to 3. GHz) freq (5. MHz to 3. GHz) Figure 6b. S22 Impedance Circle for MGA for 9MHz matching 5

6 2. MGA-31X89 Demonstration board part placement and bill of material Figure 7. A complete populated demo board for MGA & MGA Table 3 and Table 4 show the component values for both MGA and MGA for different matching frequencies. Table 4. MGA bill of material 45 MHz 9 MHz 15 MHz Unit Best RL Best RL Best RL C1 pf C2 pf C3 pf C4 pf C5 pf L1 nh L2 nh Not Needed L3 nh 27 Not Needed Table 5. MGA bill of material 19 MHz 25 MHz Unit Best RL Best RL C1 pf 1 C2 uf.1 C3 uf 2.2 C7 pf C8 pf L1 nh L2 nh Not Needed 3.9 6

7 MGA & MGA Measured Performance In this section, an optimized performance for MGA and MGA for Best Output Return Loss will be discussed in details and a comparison performance between Best Output Return Loss and performance will be shown. a) RF Performance for MGA at 45 MHz, 9 MHz and 15 MHz i. 45 MHz RF performance application Table 6 below shows the performance summary of MGA that was optimized for Best Output RL and Best OIP3 performance at 45 MHz. Figure 8 shows the performance of MGA optimized at 45 MHz for and Best OIP3 performance. At 45 MHz, the ORL for circuit is -29 db compared to Best OIP3 circuit with db. Figure 9 also shows that at 45MHz, the circuit has a better gain of 21.8 db compared to Best OIP3 circuit with 21.5 db. Table 6. Measured performance of MGA optimized at 45 MHz Unit Best Output RL Best OIP3 Vdd V 5 Id ma 74 Gain db IRL db ORL db Isolation db NF db OIP3 dbm OP1dB dbm Stability (up to 2 GHz) K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 * OIP3 test condition: F1-F2 = 1 MHz, with input power of -12 dbm per tone measured at worst case side band ORL (db) Figure 8. Measured ORL of MGA optimized at 45 MHz GAIN (db) Figure 9. Measured Gain of MGA optimized at 45 MHz 7

8 Figure 1 shows the comparison between and Best OIP3 circuit for OIP3 performance. It is evident that at 45 MHz, the OIP3 performance for degraded to dbm as compared to Best OIP3 circuit with OIP3 of dbm. OIP3 (dbm) Figure 1. Measured OIP3 of the MGA optimized at 45 MHz In short, it is clear that the application circuit provides a better ORL and gain but the OIP3 performance degrades when compared to the Best OIP3 application circuit. Figure 11 to 15 shows the RF performance of MGA (optimized at 45 MHz) across the frequencies. IRL (db) Figure 11. Measured IRL of MGA optimized at 45 MHz ISO (db) -2-3 Stability, K Figure 12. Measured isolation of MGA optimized at 45 MHz Figure 13. Measured stability, K, of the MGA OP1dB (dbm) 22. NF (db) Figure 14. Measured OP1dB of the MGA optimized at 45 MHz Figure 15. Measured NF of the MGA optimized at 45 MHz 8

9 ii. 9 MHz RF performance Table 7 below shows the performance summary of MGA that was optimized for Best Output RL and Best OIP3 performance at 9 MHz. Figure 16 shows the performance of MGA optimized at 9 MHz for and Best OIP3 performance. At 9 MHz, the ORL for circuit is db compared to Best OIP3 circuit with db. Figure 17 also shows that at 9 MHz, the circuit has a better gain of 21.4 db compared to the Best OIP3 circuit with 21.3 db. Table 7. Measured performance of MGA optimized at 9MHz Unit Best Output RL Best OIP3 Vdd V 5 Id ma 74 Gain db IRL db ORL db Isolation db NF db OIP3 dbm OP1dB dbm Stability K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 (up to 2 GHz) * OIP3 test condition: F1-F2 = 1 MHz, with input power of -12 dbm per tone measured at worst case side band ORL (db) -1-2 GAIN (db) Figure 16. Measured ORL of the MGA optimized at 9 MHz Figure 17. Measured gain of the MGA optimized at 9 MHz 9

10 Figure 18 shows the comparison between and Best OIP3 circuit for OIP3 performance. It is evident that at 9 MHz, the OIP3 performance for degraded to dbm as compared to the Best OIP3 circuit with OIP3 of dbm. In short, it is clear that the application circuit provides a better ORL and gain but the OIP3 performance degrades as compared to the Best OIP3 application circuit. Figure 19 to 23 show the RF performance of MGA (optimized at 9 MHz) across the frequencies OIP3 (dbm) IRL (db) Figure 18. Measured OIP3 of the MGA optimized at 9 MHz Figure 19. Measured IRL of the MGA optimized at 9 MHz ISO (db) -2-3 Stability, K Figure 2. Measured Isolation of the MGA optimized at 9 MHz Figure 21. Measured Stability, K, of the MGA OP1dB (dbm) NF (db) Figure 22. Measured OP1dB of the MGA optimized at 9 MHz Figure 23. Measured NF of the MGA optimized at 9 MHz 1

11 iii. 15 MHz RF performance Table 8 below shows the performance summary of MGA that was optimized for Best Output RL and Best OIP3 performance at 15 MHz. Figure 24 shows the performance of MGA optimized at 15 MHz for and Best OIP3 performance. At 15 MHz, the ORL for circuit is.6 db compared to the Best OIP3 circuit with db. Figure 25 shows that at 15 MHz, the circuit has a better gain of 21 db compared to the Best OIP3 circuit with 2.6 db. Table 8. Measured performance of MGA optimized at 15 MHz Unit Best Output RL Best OIP3 Vdd V 5 Id ma 74 Gain db IRL db ORL db Isolation db NF db OIP3 dbm OP1dB dbm Stability K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 (up to 2 GHz) * OIP3 test condition: F1-F2 = 1 MHz, with input power of -12 dbm per tone measured at worst case side band ORL (db) Figure 24. Measured ORL of the MGA at 15 MHz GAIN (db) Figure 25. Measured gain of the MGA at 15 MHz 11

12 Figure 26 shows the comparison between and Best OIP3 circuit for OIP3 performance. It is evident that at 15 MHz, the OIP3 performance for degraded to dbm as compared to the Best OIP3 circuit with OIP3 of dbm. OIP3 (dbm) Figure 26. Measured OIP3 of the MGA optimized at 15 MHz In short, it is clear that the application circuit provides a better ORL and gain but the OIP3 performance degrades as compared to Best OIP3 application circuit. Figure 27 to 31 shows the RF performance of MGA (optimized at 15 MHz) across the frequencies. IRL (db) Figure 27.Measured IRL of the MGA at 15 MHz ISO (db) -2-3 Stability, K Figure 28. Measured Isolation of the MGA at 15 MHz Figure 29. Measured stability, K, of the MGA OP1dB (dbm) 22. NF (db) Figure 3. Measured OP1dB of the MGA optimized at 15 MHz Figure 31. Measured NF of the MGA optimized at 15 MHz 12

13 b) RF Performance for MGA at 19 MHz and 25 MHz. i. 19 MHz RF Performance Table 9 below shows the performance summary of MGA that was optimized for Best Output RL and Best OIP3 performance at 19 MHz. Figure 32 shows the performance of MGA optimized at 19 MHz for and Best OIP3 performance. At 19 MHz, the ORL for circuit is db as compared to the Best OIP3 circuit with db. Figure 33 also shows that at 19 MHz, the circuit has a better gain of 2.1 db as compared to the Best OIP3 circuit with 19.6 db. Table 9. Measured performance of MGA optimized at 19 MHz Unit Best Output RL Best OIP3 Vdd V 5 Id ma 7 Gain db IRL db ORL db Isolation db NF db OIP3 dbm OP1dB dbm Stability (up to 2 GHz) K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 * OIP3 test condition: F1-F2 = 1 MHz, with input power of -12 dbm per tone measured at worst case side band ORL (db) -1-2 GAIN (db) Figure 32. Measured ORL of the MGA optimized at 19 MHz Figure 33. Measured gain of the MGA optimized at 19 MHz 13

14 Figure 34 shows the comparison between and Best OIP3 circuit for OIP3 performance. It is evident that at 19 MHz, the OIP3 performance for degraded to dbm as compared to the Best OIP3 circuit with OIP3 of dbm. In short, it is clear that the application circuit provides a better ORL and gain but the OIP3 performance degraded as compared to the Best OIP3 application circuit. Figure 35 to 39 show the RF performance of MGA (optimized at 19 MHz) across the frequencies OIP3 (dbm) IRL (db) Figure 34. Measured OIP3 of the MGA optimized at 19 MHz Figure 35.Measured IRL of the MGA optimized at 19 MHz ISO (db) Stability, K Figure 36. Measured Isolation of the MGA optimized at 19 MHz Figure 37. Measured stability, K, of the MGA OP1dB (dbm) NF (db) Figure 38. Measured OP1dB of the MGA optimized at 19 MHz Figure 39. Measured NF of the MGA optimized at 19 MHz 14

15 ii. 25 MHz RF performance Table 1 below shows the performance summary of MGA that was optimized for Best Output RL and Best OIP3 performance at 25 MHz. Figure 4 shows the performance of MGA optimized at 25 MHz for and Best OIP3 performance. At 25 MHz, the ORL for the circuit is db compared to the Best OIP3 circuit with db. Figure 41 also shows that at 25 MHz, the circuit has a better gain of 2.5 db compared to the Best OIP3 circuit with 2.2 db. Table 1. Measured performance of MGA optimized at 25 MHz Unit Best Output RL Best OIP3 Vdd V 5 Id ma 7 Gain db IRL db ORL db Isolation db NF db OIP3 dbm OP1dB dbm Stability K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 K > 1 (up to 2 GHz) * OIP3 test condition: F1-F2 = 1 MHz, with input power of -12 dbm per tone measured at worst case side band ORL (db) GAIN (db) Figure 4. Measured ORL of MGA optimized at 25 MHz Figure 41. Measured Gain of MGA optimized at 25 MHz 15

16 Figure 42 shows that the comparison between the Best ORL and Best OIP3 circuits for OIP3 performance. It is evident that at 25 MHz, the OIP3 performance for Best ORL degraded to +34dBm as compared to the Best OIP3 circuit with OIP3 of dbm. In short, it is clear that the application circuit provides a better ORL and gain but the OIP3 performance degraded as compared to the Best OIP3 application circuit. Figure 43 to 47 show the RF performance of MGA (optimized at 25 MHz) across the frequencies OIP3 (dbm) IRL (db) Figure 42. Measured OIP3 of the MGA optimized at 25 MHz Figure 43. Measured IRL of MGA at 25 MHz ISO (db) Stability, K Figure 44. Measured isolation of the MGA optimized at 25 MHz Figure 45. Measured Stability, K, of the MGA OP1dB (dbm) 22. NF (db) Figure 46. Measured OP1dB of the MGA optimized at 25 MHz Figure 47. Measured NF of the MGA optimized at 25 MHz 16

17 Conclusion The Avago Technologies MGA and MGA are fully integrated amplifiers that can be used for several frequency ranges. With proper selection of lump components, the amplifiers provide NF of 2 db, nominal gain (19.5 db or more), and very good OIP3 (>37 dbm) coincident with good input and output return loss. Avago also offers products with higher linearity (>+42 dbm OIP3) than the MGA and MGA-31489, namely MGA and MGA as shown in the table below. References 1. Application Note: High Linearity CATV Amplifier Design Simplified with the MGA-3689 Gain Block AN Application Note: Push-Pull Amplifier Design for CATV Application using Avago Technologies MGA-3x89 Amplifier Series AN 5477 Part Number Unit MGA MGA MGA MGA Frequency Band GHz.25 to to 3.25 to to 3 Gain db OIP3 dbm For product information and a complete list of distributors, please go to our web site: Avago, Avago Technologies, and the A logo are trademarks of Avago Technologies in the United States and other countries. Data subject to change. Copyright Avago Technologies. All rights reserved. AV2-2788EN - January 12, 211