Texas Instruments has introduced a new monolithic, high-linearity quadrature demodulator for direct down conversion applications. The new device is said to reduce the component count of the receive signal chain in 3G base stations by at least 75 percent, compared to superheterodyne architectures. The TRF3710 demodulator improves the RF receive signal chain by integrating all the devices required to go directly from RF to baseband onto one chip. With the addition of this device, TI now offers a more complete analog signal chain for wireless infrastructure.
The TRF3710 is optimized for use in direct down-conversion architectures where space and cost savings are key requirements. It is the first RF device in the industry to integrate a baseband filter that is software-programmable with 1-dB corner frequency, which can continuously cover signal bandwidths of 615 kHz (single carrier CDMA2000) to 1.92 MHz (single WCDMA carrier).
The device also includes a programmable gain amplifier with 24-dB of gain range in 1-dB increments, and an analog-to-digital converter (ADC) driver that allows for direct connection to the ADC. When compared to two-stage superheterodyne architectures, the TRF3710 significantly reduces overall complexity in the system by eliminating many of the receive signal chain components, including filters, mixers, a phase-locked loop (PLL) or voltage-controlled oscillator (VCO), RF and baseband amplifiers,.
The TRF3710 directly converts the RF signal to complex baseband, which ultimately reduces system cost by eliminating the need for premium, high-IF and high sample-rate ADCs. Additionally, the device provides a high linearity receiver and superior RF performance with IIP2 of 60 dB, IIP3 of 21 dB, and a noise figure of 13.5 dB.