Tiny Transistors Route Wireless Signals

March 19, 2009
Packaged transistors can provide a variety of different functions in wireless communications systems, from providing gain in oscillators to switching signals.

Packaged transistors serve a multitude of analog-signal- processing purposes in wireless systems, from amplification to switching. The latest additions to a line of packaged devices from California Eastern Laboratories cram a great deal of performance into miniature surface-mount housings that are suitable for mobile handset applications through 5.8 GHz.

For example, model UPA828TD is a "twin transistor," two discrete devices within a single leadless, 6-pin minimold package measuring 1.2 x 1.0 x 0.5 mm (Fig. 1). Having two transistors in one package can simplify the design of an oscillator, where one device is used as the active oscillation transistor and the other to buffer the oscillator output signal. The transistors are NE687 GaAs field-effect-transistor (FET) devices from NEC with typical cut-off frequency (gain-bandwidth product) of 9 GHz. They deliver 7.5 dB typical gain at 2 GHz with typical noise figure of 1.3 dB when operating from a +1-VDC supply at 3 mA. The devices are designed for maximum power dissipation of 180 mW (both devices), maximum collector-to-base voltage of 5 V, maximum collector-toemitter voltage of 3 V, and maximum collector current of 30 mA.

For switching signals, model UPG2156TB is a single-pole, doublethrow (SPDT) GaAs radio-frequencyintegrated- circuit (RFIC) usable from 800 to 2500 MHz. Designed to operate from a single control line, the compact SPDT switch features 0.45 dB typical insertion loss at 2 GHz. It can handle maximum input power of +37 dBm (with 0.1-dB loss compression) and suppresses second and third harmonics to -75 dBc. The switch achieves typical isolation of 23 dB to 1 GHz and 16.0 dB through 2.5 GHz. The typical switching speed is 1 s.

The SPDT switch is housed in an SOT-363/SC-70 equivalent TB package measuring 2.0 x 2.1 x 0.9 mm (Fig. 2). It is designed to operate with maximum supply voltage of +8 VDC and maximum control voltage of +8 VDC. It is rated for supply voltages of +2.4 to +5.0 VDC, control high voltages of +2.4 to +5.0 VDC and control low voltages of 0 to +0.2 VDC.

Finally, model NESG4030M14 is a low-noise heterojunction bipolar transistor (HBT) based on NEC's UHS4 silicon-germanium-on-carbon (SiGe:C) process. It delivers 11.5-dB typical small-signal gain at 5.8 GHz with typical noise figure of 1.1 dB. It can deliver output levels to +9 dBm at 1-dB gain compression.

The low-noise HBT is supplied in a four-pin leadless RoHS-compliant package measuring just 1.2 x 1.0 x 0.5 mm. It incorporates onboard electrostaticdischarge (ESD) protection to 80 V. The three devices are examples of lowcost, packaged semiconductor devices that support a wide range of wireless applications, from cellular handsets to remote monitoring and meter-reading applications. California Eastern Laboratories, 4590 Patrick Henry Dr., Santa Clara, CA 95054-1817; (408) 919-2500, FAX: (408) 988-0279, Internet: www.cel.com.

About the Author

Jack Browne | Technical Contributor

Jack Browne, Technical Contributor, has worked in technical publishing for over 30 years. He managed the content and production of three technical journals while at the American Institute of Physics, including Medical Physics and the Journal of Vacuum Science & Technology. He has been a Publisher and Editor for Penton Media, started the firm’s Wireless Symposium & Exhibition trade show in 1993, and currently serves as Technical Contributor for that company's Microwaves & RF magazine. Browne, who holds a BS in Mathematics from City College of New York and BA degrees in English and Philosophy from Fordham University, is a member of the IEEE.

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