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12-/14-bit ADCs target WiMAX and 3G wireless applications

Santa Clara, Calif. — National Semiconductor Corp. has launched two 12-bit 170 mega-sample per second (MSPS) analog-to-digital converters (ADCs) and a 14-bit, 155 MSPS ADC, each with a full-power bandwidth of 1.1 GHz. Available in dual-data rate, low-voltage differential signaling (LVDS) and CMOS output options, the ADCs target WiMAX and 3G wireless communications applications.

In high intermediate frequency (IF) sampling receiver applications, the 1.1 GHz bandwidth capability of these ADCs provide high spurious free dynamic range (SFDR) and signal-to-noise ratio (SNR) performance that extends beyond 250-MHz input frequencies. This enables the system designer to digitize the signal at the first IF, thereby eliminating a down conversion stage, which reduces component count and system power, said National.

The 12-bit ADC12C170 with parallel CMOS outputs and 12-bit ADC12V170 with dual-data rate, parallel LVDS outputs are said to offer the industry's highest SFDR above 250 MHz input frequencies. At an input frequency of 70 MHz, the ADC12C170 provides 85.4 dB SFDR and 67.2 dB SNR, while the ADC12V170 provides 85.8 dB SFDR and 67.2 dB SNR. Compared to competitive devices, the ADC12C170 at 84.1 dB offers 5.5 dB better SFDR and the ADC12V170 at 83 dB offers 3.8 dB better SFDR at an input frequency of 250 MHz. These characteristics make them suitable for digital pre-distortion techniques to improve power amplifier efficiency in base station applications.

The ADC12C170 operates from a 3.3V supply and typically consumes 715 mW, while the ADC12V170 typically consumes 781 mW. Both ADCs include a power-down feature to reduce power consumption to 5 mW.

At 1.1 GHz, the ADC14V155 delivers 57 percent higher full-power bandwidth than competing 14-bit ADCs. The device also provides a SFDR of 85 dB and SNR of 69.5 dB at an input frequency of 238 MHz. In addition, the device's low-jitter front-end allows the digitization of high frequency inputs up to 450 MHz. The 14-bit ADC operates from a 3.3-V supply and typically consumes 951 mW. It offers a power-down feature to reduce power consumption to 15 mW, while a separate 1.8-V supply for the digital interface allows low-power operation with reduced noise.

Pricing: Supplied in 48-pin LLP packages, the 12-bit ADC12C170 and 12-bit ADC12V170 are priced at $39.20, and the 14-bit ADC14V155 is priced at $67.10 in quantities of 1,000.
Availability: Available now including samples and evaluation boards.
Product information: ADC12C170, , ADC12V170, , ADC14V155, and data conversion products

National Semiconductor , www.national.com

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