Electronic Design

IQ Demodulator Cuts 3G Basestation Component Count By 75%

The TRF3710 quadrature demodulator from Texas Instruments manages direct downconversion in 3G basestations. Using this device in place of the traditional superheterodyne architectures common in infrastructure designs reduces the need for external filters, attenuators and amplifiers, and other support circuits, cutting component count in the receive chain by as much as 75%.

The TRF3710 is the first RF device to integrate a software-programmable baseband filter with 1-dB corner frequency and cover signal bandwidths of 615 kHz in single-carrier cdma2000 applications to 1.92 MHz in single-carrier WCDMA applications. The chip also includes a programmable gain amplifier (PGA) with a maximum gain up to 24 dB programmable in 1-dB increments.

A built-in analog-to-digital converter (ADC) driver allows for direct connection to the ADC. Typical specs include a second-order intercept of 60 dB, a third-order intercept of 21 dB, and a noise figure of 13.5 dB. The programming interface is a three-wire serial peripheral interface (SPI).

The TRF3710 is available in a 48-pin quad flat no-lead (QFN) package. It costs $9.75 each in 1000-unit lots. Other TI products targeting the wireless infrastructure include the TRF3703 quadrature modulator, the TRF3761 low-noise phase-locked loop frequency synthesizer, and the ADS5231, ADS5240, and ADS5270 ADCs.

Texas Instruments


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