45-MHz AFE Boosts Performance Of Office Peripherals

Operating at speeds up to 45 MHz, the LM98714 three-channel, 16-bit analog front end (AFE) from National Semiconductor Corp. improves the performance of multifunction peripherals intended for small-office environments. The IC is the first AFE to integrate a programmable timing generator for charge-coupled devices or contact image sensors as well as serial low-voltage differential signaling output, according to NSC. Signal-to-noise ratio is -74 dB, and power consumption is 505 mW. The highly integrated device offers color copying speeds of more than 40 pages per minute, but it is also well-suited for use in bank-note readers, high-speed document scanners, facsimile equipment, and flatbed or handheld color scanners.

The LM98714 employs either correlated double sampling (CDS) or sample-and-hold (S/H) inputs. The AFE also has signal paths that use a 10-bit offset correction digital-to-analog converter (DAC), 8-bit programmable gain amplifiers (PGAs), and independently controlled digital black-level correction loops for each input. The PGAs and DAC are programmed independently, which allows unique values of gain and offset for each of the three inputs. For maximum flexibility, the LM98714 can be configured in operate in several different modes. A CMOS output option ensures compatibility with older application-specific ICs and simplifies system debugging. The device comes in a 48-pin TSSOP.