DATA SHEET SKY65050-372LF: 0.45-6.0 GHz Low Noise Transistor Applications Wireless infrastructure: WLAN, WiMAX, broadband, cellular base stations Test instrumentation LNA for GPS receivers Satellite receivers Figure 1. SKY65050-372LF Block Diagram Features Externally matched for wideband operation Description Noise Figure = 0.45 dB 2.4 GHz of device only The SKY65050-372LF is a high performance, n-channel low-noise Noise Figure = 0.65 dB 2.4 GHz including matching network transistor. The device is fabricated from Skyworks advanced loss depletion mode pHEMT process and is provided in a Gain = 15.5 dB 2.4 GHz 2.20 x 1.35 x 1.10 mm, 4-pin SC-70 package. OIP3 = +23.5 dBm 2.4 GHz, VDD = 3 V, IDD = 20 mA rd The transistors low Noise Figure (NF), high gain, and excellent 3 P1dB = +10.5 dBm 2.4 GHz, VDD = 3 V, IDD = 20 mA Order Intercept Point (IP3) allow the device to be used in various receiver and transmitter applications. Adjustable supply current, 5 to 55 mA A functional block diagram is shown in Figure 1. The pin Small, SC-70 (4-pin, 2.20 x 1.35 x 1.10 mm) package (MSL1, configuration and package are shown in Figure 2. Signal pin 260 C per JEDEC J-STD-020) assignments and functional pin descriptions are provided in Table 1. Figure 2. SKY65050-372LF Pinout 4-Pin SC-70 (Top View) Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com 200967G Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice November 14, 2012 1 DATA SHEET SKY65050-372LF LOW NOISE TRANSISTOR Table 1. SKY65050-372LF Signal Descriptions Pin Name Description Pin Name Description 1 SOURCE Source lead. Provides DC self-biasing point 3 SOURCE Source lead. Provides DC self-biasing point and AC ground. and AC ground. 2 DRAIN RF output. Requires external matching 4 GATE RF input. Requires external matching network for optimum performance. Supply network for optimum performance. voltage required through external RF choke. Table 2. Self-Biasing Resistors Resistor Value ( ) Drain Current (mA) 130 5 47 10 27 15 20 20 15 25 10 30 desired negative VGS value. This simplifies the design by Functional Description eliminating the need for a second DC supply. The SKY65050-372LF is a depletion mode pHEMT designed for low noise, high frequency applications. The SKY65050-372LF has Table 2 provides the resistor values used to properly bias the a typical NF of 0.65 dB tested at the 2.4 GHz wireless LAN SKY65050-372LF. frequency band. A gain of 15.5 dB typical is achieved using the same circuit. If the frequency of operation is lowered to the 1 GHz RF Matching Networks range, NF performance of the device can approach 0.5 dB The SKY65050-372LF Evaluation Board assembly diagram is including input matching network losses. shown in Figure 12 and a circuit schematic is provided in De-embedded scattering and noise parameters are provided in Figure 13. The schematic shows the recommended RF matching addition to typical circuit topologies for commonly used frequency network used for the 2.4 GHz wireless LAN frequency band. The bands. With an appropriate circuit, the SKY65050-372LF can be network was designed using de-embedded s- and n-parameters. used for many applications from 450 MHz up to 6 GHz. The The circuit was primarily tuned for gain, NF, and input and output compact SC-70 package makes the SKY65050-372LF an ideal return loss, while maintaining proper stability. low noise and low cost solution. Optimal noise performance is attained when the impedance presented to the input of the amplifier is equal to its minimum NF Biasing impedance point. Components C1, C2, C3, L1, and L2 shown in To properly bias a depletion mode pHEMT, both the gate and drain Figures 12 and 13 provide the necessary impedance match for NF of the device must be properly biased. At VGS = 0 V and and input return loss. Circuit board and input matching structure VDS 2 V, the device is in a saturated state and draws the losses on the input of the amplifier directly add to the overall NF of maximum amount of current, IDSS. The device typically achieves the amplifier. It is critical to minimize RF trace lengths and to use the best noise performance at VDS = 3 V and IDSS = 15 mA. To high-Q components to achieve optimal NF performance. control IDS, VGS must be biased with a negative voltage supply. Components R2 and C14 provide self biasing for the device and To eliminate the need for a negative DC supply, self-biasing RF grounding for one of the two source leads. Components C5 and should be used when a resistor is placed between one of the L3 are placed on the opposing source lead and are used to tune source leads and ground. A bypass capacitor should be placed in the transistors source inductance. parallel to this resistor to provide an RF ground and to ensure performance remains unchanged at the operating frequency. When current flows from drain to source and through the resistor, the source voltage becomes biased above DC ground. The gate pin of the device should be left unbiased at 0 V, which creates the Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com 2 November 14, 2012 Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice 200967G