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Analog Devices recently introduced the first dual 14-bit analog-to-digital converter (ADC) to achieve sampling rates of 150 Msps. Supporting all third-generation (3G) base station wireless standards, including W-CDMA, CDMA2000 and TD-SCDMA, the AD9640 is the only dual 14-bit ADC that samples at rates beyond 135 Msps, a common requirement for the emerging worldwide interoperability for microwave access (WiMAX) standard.

With the AD9640, base station designers are able to reach higher sampling rates with one dual ADC, enabling a 50% reduction in board space requirements. Additionally, the AD9640 simplifies the design of multicarrier wireless infrastructure systems by decreasing the amount of analog filtering in front of the ADC and offering low power consumption.

The new ADC delivers best-in-class performance, while only consuming 390 mW of power per channel. The AD9640 offers signal-to-noise ratio (SNR) of 72.7 dBFS and spurious free dynamic range (SFDR) of 85 dBc with a 70 MHz intermediate frequency (IF). It is also capable of supporting IFs as high as 450 MHz, enabling WiMAX designers to use a single downconversion receiver design instead of the traditional two downconversion stages. For optimal performance, the AD9640 can be driven with ADI’s AD8352 low distortion differential amplifier.

Incorporated on the AD9640 are digital features that reduce system costs by simplifying the automatic gain control (AGC) loop in the receiver. The new converter is the industry’s first to integrate digital features including a block that monitors the incoming composite signal power, and indicates whether the gain of the receiver needs to be increased or decreased. While the signal monitor block can act as a slow mechanism to change the receiver gain, the AD9640 also includes fast detect (FD) modes, allowing designers to detect an input over-range condition in as little as 2 clock cycles, immediately reducing the gain to avoid overdriving the analog front end. In addition to providing clipping information, the FD bits have programmable thresholds that are useful in optimizing the receiver AGC loop.

The AD9640 is sampling with production quantities available in April. The ADC is available in 12-bit and 14-bit resolutions with sample rates of 80, 105, 125 and 150 MSPS. CMOS and LVDS output modes are supported. The 14-bit ADC is priced between $37.50 and $87.50 and the 12-bit ADC is priced between $25.05 and $47.97 in 1,000-piece quantities. Both versions are packaged in a 9 mm × 9 mm 64-lead lead-frame chip-scale package.