wirelessZONE Products for the week of June 6, 2005
Texas Instruments Says . . .
TRF2432/36: Portfolio Of RF Products For Broadband
Wireless
Chipsets at 2.5 GHz, 3.5 GHz and 5.8 GHz Available for Wireless
Broadband Base Stations and Access Points
Texas Instruments expands its portfolio of complete wireless signal-chain solutions for broadband wireless access, introducing three radio frequency (RF) chipsets, the TRF11xx chipset at 2.5 GHz, the TRF12xx chipset at 3.5 GHz and the TRF24xx chipset at 5.8 GHz. TI´s new chipsets are designed to support IEEE 802.16d/e standard RF front end for wireless base stations, access points as well as equipment backhaul, point-to-point microwave and public safety band applications. These new chipsets are capable of supporting both emerging WiMAX and WiBro applications based on the IEEE 802.16 standard, as well as the more traditional fixed wireless access.
"TI is working with equipment providers to build a solid foundation to deploy any type of broadband infrastructure demanded in the future," said David Briggs, TI's analog wireless infrastructure business manager. "We understand that as carriers look to incorporate the newest applications that they expect technologies, such as 802.16, to be readily available. TI is best equipped to ensure that equipment providers have the tools and flexibility they need to support emerging access technologies in the shortest timeframe."
2.5 GHz and 3.5 GHz Flexible RF Chipsets with Power Amplifiers
Both the TRF112xx chipset at 2.5 GHz and the TRF122xx chipset at 3.5 GHz
consist of four chips, each with fully integrated super heterodyne receivers
and transmitters. These RF chipsets are capable of supporting Frequency
Division Duplex (FDD), Half Frequency Division Duplex (HFDD) and Time Division
Duplex (TDD) modes with a real interface at low IF to the data conversion
subsystem. TI´s flexible RF chipsets are compliant with today´s
demanding mask requirements, while the receivers feature excellent sensitivity
and blocker suppression.
The TRF11xx at 2.5 GHz and the TRF12xx at 3.5 GHz are also complemented by the optimized power amplifiers, TRF1123 and TRF1223. Supporting a range of frequencies between 2.1 - 2.7 GHz and 3.3 - 3.8 GHz, these power amplifiers provide excellent output third order intercept point (OIP3) of 45dBm or better, enabling the support of complex OFDM (orthogonal frequency division multiplexing) signals. These power amplifiers can also be used as driver amplifiers in applications requiring larger output power.
5.8 GHz Integrated Chipset
TI´s new TRF2432 and TRF2436 heterodyne transceiver chipset is the
most integrated solution available, with two chips. Consisting of an IF
and RF transceiver, the chips supports 4.9 - 5.9 GHz air interface frequency
band. The chipset supports TDD mode with complex I/Q interface. This highly
integrated chipset reduces space, making for easier design while saving
bill of material (BOM) cost.
analogZONE Says . . .
These two ICs are ASICs that offer the complete front-end and conversion to/from baseband in the 2.4-GHz ISM band (up to 2.5 GHz) and an expanded upper band of 4.9 GHz to 5.9 GHz, including the 5.8-GHz ISM band.
The TRF2436 is the RF front-end with dual transmit/receive switches on-chip and dual, gain-controlled, LNAs. The signals then exit the chip to go through an external, probably ceramic, band-pass filter. Back on chip the signals a mixed down to a 374 MHz IF. A single output is provided for either/or mixer outputs and the incoming LO is also switched either/or to the mixers. On the transmit side the same IF and LO lines is used, as are the same mixers, to produce the final frequencies. Those also pass through the same external filters before being amplified to the transmit/receive switches. Diode detectors on the RF outputs (with quite linear characteristics) are OR'd to a common detector line. Apart from the external filters only three external low-power MOSFETs are required for power switching while pins are provided for bias control on the PAs.
Typical receiver noise figures from the TRF2436 are 4 dB for the lower band and 6 dB for the upper band and those coupled with the power requirements suggest that this an SiGe part. Gain numbers are unknown as there appear to be some typos on the preliminary data sheet, but are in the 20s of dB. Gain flatness on both the receive and transmit channels are within 1 dB on the low band and 2 dB on the high band.
Receive P1dB (at high-gain) for the TRF2436 are -17 dBm for the low band and -18 dBm for the high band, while OIP3 are -1 dBm and -8 dBm. LO leakage numbers are better than -30 dBm while the input return losses are both +8 dB, which probably suggests a little external matching in critical designs. Power consumption (3.3-V nominal rail) in receive mode is a typical 65 mA, low band, and 80 mA, high band. Maximum numbers in transmit are 410 mA and 450 mA.
On the transmit side of the part the gains are 40 dB and 43 dB (low/high) with the P1dBs at 23.5 dBm and 22.5 dBm, and the OIP3s at 35 dBm and 32.5 dBm. The IF input return loss is just 8 dB. The PA harmonics on both channels are lower than -20 dBc when they are driven CW at P1dB.
The TRF2432 is called an IQ/IF "transceiver" by TI with both receive and transmit I/Q modulation channels. Gain control is in the first stage on the receive side and the last stage on the transmit side. On-chip low-pass filters follow the demodulation on the receive channels with a dc offset calibration capability following, and a buffer precedes the modulation on the transmit side.
The LO signal is produced from an on-chip synthesizer separately from the IF synthesization but both use the same external crystal (at either 40 MHz or 44 MHz). The LO output can range from 2650 MHz to 3150 MHz in 250 kHz tuning steps. Phase noise is -130 dBc/Hz at 4.5 MHz offset.
There are five power modes in the TRF2432: Off, sleep, standby, idle, and active. In the sleep mode power is connected but all the circuits are powered down. The maximum current drain (3.3 V rail) is 10 µA. In standby mode the oscillator is running with the REF OUT buffer active (at the crystal frequency), the registers are active and the serial port is active -- typical current drain is 10 mA. In idle mode the RF and IF synthesizers are powered up -- 70 mA. In active mode either the complete receive, or complete transmit, channel is powered -- 90 mA for receive, 100 mA transmit. The change between power modes is not a sequence, mode can be changed on the fly between all four powered modes.
This is a heavy-hitting pair of ICs that have terrific potential for Wi-MAX and other similar applications. There are other ICs out there and it would take a serious lab to compare them all before making a design decision, but this pair is timed right for the market.
Not yet publicly priced, and with no general samples available, the TRF2432 will be in a Pb-free thermally-enhanced LPCC-56 and the TRF2436 will be in a Pb-free thermally-enhanced LPCC-40.
Data
Sheet TRF2432
Data
Sheet TRF2436