Features: Low cost 3.3 V CMOS MxFE(TM) for broadband applications
DOCSIS, EURO-DOCSIS, DVB, DAVIC compliant
232 MHz quadrature digital upconverter
12-bit direct IF DAC (TxDAC+(R))
Up to 65 MHz carrier frequency DDS
Programmable sampling clock rates
Analog Tx output level adjust
Dual 12-bit, 29 MSPS direct IF ADCs with video clamp input
10-bit, 29 MSPS sampling ADC
8-bit -? auxiliary DAC
Direct interface to AD832x family of PGA cable drivers
ApplicationCable set-top boxes
Cable and wireless modems
Pinout
Specifications
| Parameter |
Rating |
Power Supply (VAVDD, VDVDD, VDRVDD)
Digital Output Current
Digital Inputs
Analog Inputs
Operating Temperature
Maximum Junction Temperature
Storage Temperature
Lead Temperature (Soldering, 10 sec) |
3.9 V
5 mA
-0.3 V to VDRVDD + 0.3 V
-0.3 V to VAVDD + 0.3 V
-40°C to +85°C
150°C
-65°C to +150°C
300°C |
DescriptionThe AD9878 is a single-supply, cable modem/set-top box, mixed-signal front end. The device contains a transmit path interpolation filter, a complete quadrature digital upconverter, and a transmit DAC. The receive path contains dual 12-bit ADCs and a 10-bit ADC. All internally required clocks and an output system clock are generated by the phase-locked loop (PLL) from a single crystal oscillator or clock input.
The transmit path interpolation filter provides an upsampling factor of 16* with an output signal bandwidth up to 4.35 MHz. Carrier frequencies up to 65 MHz with 26 bits of frequency tuning resolution can be generated by the direct digital synthesizer (DDS). The transmit DAC resolution is 12 bits and can run at sampling rates as high as 232 MSPS. Analog output scaling from 0 dB to 7.5 dB in 0.5 dB steps is available to preserve SNR when reduced output levels are required.
The 12-bit ADCs provide excellent undersampling performance, allowing this device to typically deliver better than 10 ENOBs with IF inputs up to 70 MHz. The 12-bit IF ADCs can sample at
rates up to 29 MHz, allowing them to process wideband signals.
The AD9878 includes a programmable -? DAC, which can be used to control an external component such as a variable gain amplifier (VGA) or a voltage controlled tuner.
The AD9878 also integrates a CA port that enables a host processor to interface with the AD832x family of programmable gain amplifier (PGA) cable drivers or industry equivalent via
the MxFE serial port (SPORT).
The AD9878 is available in a 100-lead, LQFP package. The AD9878 is specified over the extended industrial (-40°C to +85°C) temperature range.
AD9878 Data Sheet
