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AN11135

Replacing HMC625 by NXP BGA7204

Rev. 2.0 — 10 December 2011

Application note

Document information

Info

Content

Keywords

BGA7204, VGA, HMC625, cross reference, drop-in replacement,

OM7922/BGA7204 Customer Evaluation Kit

Abstract The document provides guidelines to replace the HMC625 manufactured

by Hittite Microwave Corporation by the NXP BGA7204 Variable Gain

Amplifier. It includes circuit, BOM and performance information.

Summary The BGA7204 Variable Gain Amplifier can replace the HMC625 without

changing any of the external components. It will yield the similar

performance as the HMC625 from 700 MHz to 2850 MHz.

Compared to the HMC625 the BGA7204 requires less external

components, which allows for further simplification of the circuitry.

The BGA7204 assumes the HMC625 SPI mode. However the BGA7204

features an extended Serial Peripheral Interface (SPI) which can be

enabled by simply exchanging one SMD component.

Summary of content (16 pages)

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AN11135 Replacing HMC625 by NXP BGA7204 Rev. 2.0 — 10 December 2011 Application note Document information Info Content Keywords BGA7204, VGA, HMC625, cross reference, drop-in replacement, OM7922/BGA7204 Customer Evaluation Kit Abstract The document provides guidelines to replace the HMC625 manufactured by Hittite Microwave Corporation by the NXP BGA7204 Variable Gain Amplifier. It includes circuit, BOM and performance information.
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AN11135 NXP Semiconductors BGA7204 Revision history Rev Date Description 2.0 20111210 Reviewed document 1.0 20111129 Initial document Contact information For more information, please visit: http://www.nxp.com For sales office addresses, please send an email to: salesaddresses@nxp.com AN11135 Application note All information provided in this document is subject to legal disclaimers. Rev. 2.0 — 10 December 2011 © NXP B.V. 2011. All rights reserved.
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AN11135 NXP Semiconductors BGA7204 1. Introduction This document describes how to replace the VGA HMC625 manufactured by Hittite Microwave Corporation by the NXP BGA7204. The BGA7204 MMIC is an extremely linear Variable Gain Amplifier (VGA), operating from 0.4 GHz to 2.75 GHz. At minimum attenuation it has a gain of 18.5 dB, an output IP3 of 38 dBm and a noise figure of 7 dB. The attenuation range is 31.5 dB with an attenuation step of 0.5 dB.
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AN11135 NXP Semiconductors BGA7204 2.2 Schematic In the picture below the BGA7204 is placed in the HMC625 reference application circuit, without changing any of the external components. Not all components are needed, but this drop-in approach could simplify the component qualification at the customer side, at the expense of placing unnecessary components. Fig 2. The HMC625 application circuit using NXP’s BGA7204. 2.3 Component list In the Table below the used components have been listed.
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AN11135 NXP Semiconductors BGA7204 Component HMC625 Low cost BGA7204 data sheet performance C7 100 pF 100 pF 100 pF C8 100 pF 100 pF 100 pF C9 100 pF 100 pF 1 nF C11 1 nF 1 nF 47 nF C12 1 nF 1 nF 100 pF C14 2.2 µF 2.2 µF 4.7 µF [3] 24 nH 24 nH 47 nH R15 1.8 Ω 1.8 Ω or 0 Ω 0Ω L1 [1] Place 0 Ω jumper to use the BGA7204’s extended SPI mode. [2] 1 nF decoupling capacitor C9 value will remove 300 MHz dip, see Chapter 3.
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AN11135 NXP Semiconductors BGA7204 S21 (in dB) S21 vs Frequency (Gmax = DSA 63) 20 18 16 14 12 10 8 6 4 2 S21 BGA7204 BOM S21 HMC625 BOM 0 1 2 3 4 3 4 3 4 Frequency (in GHz) S21 vs Frequency (Gmid = DSA 32) 4 2 S21 (in dB) 0 -2 -4 S21 BGA7204 BOM -6 S21 HMC625 BOM -8 -10 -12 0 1 2 Frequency (in GHz) S21 vs Frequency (Gmin = DSA 0) -10 -12 S21 (in dB) -14 -16 -18 S21 BGA7204 BOM -20 S21 HMC625 BOM -22 -24 -26 0 1 2 Frequency (in GHz) Fig 3.
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AN11135 NXP Semiconductors BGA7204 2.4.1.2 Input return loss The component value of the RF choke (L1 = 24 nH instead of 47 nH) also has minor influence on the input return loss.
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AN11135 NXP Semiconductors BGA7204 2.4.1.3 Output return loss The component value of the RF choke (L1 = 24 nH) has influence on the output return loss. For frequencies below 700 MHz it might make sense to improve this by changing the component value of the RF choke (L1 = 47 nH instead of 24 nH), see Chapter 3.
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AN11135 NXP Semiconductors BGA7204 2.4.2 Output third order intercept point No degradation on OIP3 for frequencies above 700 MHz by using the HMC625 bill of material. The OIP3 at 400 MHz drops 0.7 dB, resulting from the gain drop at frequencies below 700 Mhz. The component value of the RF choke (L1 = 24 nH) causes the gain drop. This can be improved, see Chapter 3.
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AN11135 NXP Semiconductors BGA7204 Pout at 1dB Compression vs Frequency (Gmax = DSA 63) 30 28 P1dB (in dBm) 26 24 22 20 18 P1dB HMC625 BOM 16 P1dB BGA7204 BOM 14 12 10 0 0.5 1 1.5 2 2.5 3 Frequency (in GHz) Fig 7. P1dB out, BGA7204 using BGA7204 BOM and the HMC625 BOM 3. Tips and tricks The application circuitry described in Chapter 2 leaves the bill of material of the HMC625 reference application circuitry intact. This means that unnecessary external components are being placed.
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AN11135 NXP Semiconductors BGA7204 3.3 Using extended SPI mode The BGA7204 can be set to extended SPI mode which allows extra features (like chip temperature read out), to use this mode some changes on the BOM has to be done. The position on the printed circuit board for the capacitor C2 needs to be used to ground pin 7, by placing a 0 Ω jumper. See also the table of paragraph 2.3 component list column ‘BGA7204 Data Sheet performance.
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AN11135 NXP Semiconductors BGA7204 Removing 300 MHz dip (Gmax = DSA = 63) 25 20 15 S21 SWAP Capacitor S21 & S22 (in dB) 10 5 S21 HMC625 BOM 0 S22 SWAP Capacitor S22 HMC625 BOM -5 -10 -15 -20 -25 0 200 400 600 800 1000 Frequency (in GHz) Fig 8. AN11135 Application note Gain and output return loss at minimum attenuation of the BGA7204 using the printed circuit board of the OM7922/BGA7204 Customer Evaluation Kit. The effect of swapping C9 and C12 is shown, see text.
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AN11135 NXP Semiconductors BGA7204 4. Legal information 4.1 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. 4.
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AN11135 NXP Semiconductors BGA7204 5. List of figures Fig 1. Fig 2. Fig 3. Fig 4. Fig 5. Fig 6. Fig 7. Fig 8. Top layer printed circuit board of the BGA7204 Customer Evaluation Kit (OM7922/BGA7204). . 3 The HMC625 application circuit using NXP’s BGA7204. ......................................................... 4 Gain at max, mid and min attenuation. ............. 6 Input return loss at max, mid and min attenuation ........................................................
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AN11135 NXP Semiconductors BGA7204 6. List of tables Table 1. Components values for drop-in replacement (column: HMC625), for low cost replacement (column: Low cost) and for obtaining BGA7204 performance as published in the BGA7204 data sheet (column: BGA7204 data sheet performance)..................................................... 4 AN11135 Application note All information provided in this document is subject to legal disclaimers. Rev. 2.0 — 10 December 2011 © NXP B.V. 2011.
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AN11135 NXP Semiconductors BGA7204 7. Contents 1. 2. 2.1 2.2 2.3 2.4 2.4.1 2.4.1.1 2.4.1.2 2.4.1.3 2.4.2 2.4.3 3. 3.1 3.2 3.3 3.4 4. 4.1 4.2 4.3 5. 6. 7. Introduction ......................................................... 3 Application Circuit for drop-in replacement ..... 3 OM7922/BGA7204 Customer Evaluation Kit ..... 3 Schematic .......................................................... 4 Component list ................................................... 4 Measurements .............................