RFMD® Low Noise Amplifiers Provide Broadband Performance for Multi-Market Applications
By BJ Lyman, Frank Nicosia and Phil Garber, RFMD

RFMD® introduces the first series (RF386X) of pseudomorphic high electron mobility transistors (pHEMT) low noise amplifiers (LNAs) to their Multi-Market Products Group (MPG) product offering. RFMD’s newly formed MPG designs and develops RF Integrated Circuits (RFIC) for the cellular infrastructure, broadband cable television (CATV), wireless connectivity, and aerospace and defense markets. The RF386X series of LNAs, consisting of single-stage, dual-stage, and dual-channel architecture, provide users with a variety of design choices, broadband performance, and ease of integration. (See Table 1a)

Table 1a: Product Overview
Utilizing a 0.25µ gate-length pHEMT process, the RF386X series achieves competitive in-package noise figures (NF)ranging from 0.8dB to 1.2dB as well as excellent OIP3 performance of up to 36 dBm. With a broad frequency range of operation (700 MHz to 3800 MHz), the 386X series provides an extremely flexible platform design approach affording cost savings through economy of scale. The LNAs are self-biased, 50 ohm matched, and incorporate input and output DC blocking capacitors. A variety of printed circuit board assemblies (PCBA) are outlined in each datasheet, optimizing performance for key applications ranging from CDMA, PCS, UMTS, WLAN, and WiMax.

In addition, a single match may be used over an extended frequency range, simplifying design, lowering PCBA costs, and speeding time to market. For example, the single-stage amplifiers (RF3861, RF3863 & RF3867) can be matched from 1.5-2.7 GHz, while the dual-stage amplifiers (RF3865, RF3866) operate over a 2 GHz bandwidth. (See Figure 1b)

Note: 34 – 38 dBm OIP3 is maintained over the whole 1.8 – 3.8 GHz band. OP1dB is a flat 22 dBm.

Adding to the flexibility of these LNAs is the single supply voltage requirement ranging from 3.0 volts to 6.0 volts. In addition, one might utilize these as driver amplifiers by incorporating an external resistor which increases bias and adds 1.0-1.5 dB in OIP3. Low thermal resistance provides very high reliability operation.

The RF3861 and RF3863 are both single-stage amplifiers providing Gain of up to 15dB, while the RF3865 and RF3866 are dual-stage amplifiers providing gain of up to 30dB. The RF3867 is a dual-channel design providing 15dB of gain (each channel) for applications utilizing multiple transmit or receive channels (See Table 2a). This integrated dual-channel design approach provides multi-channel users a single part solution, which lowers part count and overall cost while providing improved performance through the incorporation of two paths into one RFIC, hence lowering system insertion losses.

Each part in this family is integrated into a low-cost QFN package available as 25-piece bags, and standard tape-and-reel configurations ranging from 100 pieces (RF386X-SR), 750 pieces (-TR7), or 2500 pieces (-TR13). Custom designs are also supported through the availability of fully assembled evaluation boards pre-configured for either 0.7-1.1 GHz (RF386XPCK-412), 1.5-2.7 GHz (PCK-410), or 3.3-3.8 GHz (PCK-411).
 
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