AD9869is a mixed-signal front-end (MxFE)® IC for transceiver applications requiring transmit path and receive path functionality at data rates up to 80 MSPS. The device is a low cost, pin-compatible version of the AD9866 that removes the current amplifier (IAMP) IOUTP function and limits the PLL VCO operating frequency range to 80 MHz to 200 MHz.
The device is ideal for half- and full-duplex applications. The flexibility of this digital interface allows for simple interfacing with digital backends that support half- or full-duplex data transmission, so the AD9869 is often used to replace discrete ADC and DAC solutions. Power-down modes can reduce power consumption for individual function blocks or shut down unused modules in half-duplex applications. The serial port interface (SPI) allows software programming of many functional blocks. The on-chip PLL clock multiplier and synthesizer provide all required internal clocks, as well as external clocks for single crystal oscillators or clock sources.
The transmit signal path consists of a 2×/4× low-pass interpolation filter, a 12-bit TxDAC, and line drivers. At an input data rate of 80 MSPS, the transmit path signal bandwidth can be as high as 34 MHz. The TxDAC provides a differential current output that can be directed directly to an external load or to an internal low distortion current amplifier (IAMP) capable of delivering 17 dBm peak signal power. The transmit power can be digitally controlled over a range of 19.5 dB in 0.5 dB steps.
The receive path consists of a programmable amplifier (RxPGA), a tunable low-pass filter (LPF), and a 12-bit ADC. The low-noise RxPGA has a programmable gain range of −12 dB to +48 dB in 1 dB steps; For gain settings above 36 dB, the input-referred noise is less than 3 nV/√Hz. The receive path LPF cutoff frequency can be set from 15 MHz to 35 MHz or simply bypassed. The 12-bit ADC achieves excellent dynamic performance up to 80 MSPS. Both the RxPGA and ADC provide adjustable power consumption for power/performance optimization.
The AD9869 provides a highly integrated solution for many broadband modems. It is available in a space-saving 16-pin LFCSP package and is specified over the commercial temperature range of −40°C to +85°C.
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