RF Chip Sets Support 802.16d/e Front Ends

Aug. 19, 2005
These 2.5- and 3.5-GHz chip sets provide multiple duplex modes while a 5.8-GHz offering includes both the RF and IF transceivers.

Broadband wireless market forecasts predict huge opportunities, despite the fact that sales are still modest. To give the broadband market a boost, Texas Instruments (Dallas, TX) recently introduced three RF chip sets at various frequencies: the TRF11xx chip set at 2.5 GHz, the TRF12xx chip set at 3.5 GHz, and the TRF24xx chip set at 5.8 GHz. The chip sets support frequency-division-duplex (FDD), half-frequency-division-duplex (HFDD), and time-division-duplex (TDD) modes and include an interface to link intermediate-frequency (IF) outputs with a data-conversion system. They are fully compliant with IEEE 802.16d/e and support portable mobile applications like WiMAX and WiBro.

The 2.5-GHz TRF112x and 3.5-GHz TRF122x chip sets comprise four chips. Each chip boasts fully integrated superheterodyne receivers and transmitters. The operating frequency of the TRF112x chip set ranges from 2.3 to 2.7 GHz. Its transmission specifications include output power at 1-dB compression (P1dB) of +31.5 dBm, +48-dBm output third-order intercept point (OIP3), 0.5° RMS phase error, and 80 dB of digital gain control (in 1-dB steps). The receiver figures for the TRF112x include 4 dB of cascaded noise figure (NF), P1dB of –3 dBm, and a maximum gain of nearly 100 dB. The chip set has a local-oscillator (LO) RMS phase error of 0.5°, an automatic-gain-control (AGC) range of almost 90 dB, with differential output voltage of better than 1.2 Vp-p.

The 3.5-GHz TRF122x operates from 3.3 to 3.8 GHz. It boasts P1dB of +30 dBm, OIP3 of +45 dBm, and phase error of 0.5° RMS. The chip has 80-dB digital gain-control range in 1-dB steps. Its receiver section includes cascaded NF of better than 3.5 dB, P1dB of +5 dBm or more, and maximum gain of almost 110 dB. The LO RMS phase error is 0.5°. The chip has an AGC range of nearly 100 dB and better than 1.2 Vp-p differential output voltage.

Two optimized power amplifiers complement these chip sets. The TRF11233 and TRF1223 support a range of frequencies between 2.1 and 2.7 GHz and from 3.3 to 3.8 GHz, respectively. To enable the support of orthogonal-frequency-division-multiplexing (OFDM) signals, these power amplifiers provide an OIP3 of +45 dBm or better. In applications that require more output power, the power amplifiers can be used as driver amplifiers.

Compared to its lower-frequency siblings, the 5.8-GHz chip set flaunts a higher level of integration. Both variations of this chip set—the TRF2432 and TRF2436—are two-chip solutions consisting of an IF and RF transceiver (see figure). The chips support the 4.9-to-5.9-GHz air-interface frequency band. The 5.8-GHz chip sets also support TDD mode with a complex I/Q interface. Due to their high level of integration, they also promise to reduce space. The chip sets strive to simplify design while lowering bill-of-material (BOM) costs.

The TRF243x operates from 4.9 to 5.9 GHz. Its transmission specifications include the following: +22.5 dBm P1dB, +32.5 dBm OIP3, 1.2° RMS phase error, and 31-dB digital gain control in 1-dB steps. The TRF243x's reception performance is defined by a cascaded NF of 6 dB, P1dB of –3 dBm, and maximum gain of almost 94 dB. The chip set boasts a LO RMS phase error of 1.2° and an AGC range approaching 75 dB.

The release of this chip-set family underscores TI's plans to provide a complete analog-signal-chain solution for wireless-infrastructure OEMs. The new chip sets add to this effort by acting as complete RF front-end solutions for the 2.5-, 3.5-, and 5.8-GHz wavebands. They provide support for fixed wireless access as well as emerging portable and mobile applications. As a result, the chip sets could be used in a variety of applications. Examples include wireless base stations, point-to-point microwave, wireless access points, safety band, customer premise equipment (CPE), and backhaul.

All three chip sets are available in lead-free and RoHS-compliant packaging. Samples and reference designs are available for all three chip sets. Texas Instruments, Inc., 12500 TI Blvd., Dallas, TX 75243-4136; (800) 336-5236, Internet: www.ti.com.

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