The LM98620 is a fully integrated, 10-Bit, 70 MSPS signal
processing solution for high performance digital color copiers,
scanners, and other image processing applications. Highspeed
signal throughput is achieved with an innovative six
channel architecture utilizing Correlated Double Sampling
(CDS), or Sample and Hold (SH) type sampling. 1x or 2x gain
settings are available in the CDS/SH input stage. Each channel
has a dedicated 1x to 10x (8 bit) PGA that allows accurate
gain adjustment of each channel. The Digital White Level auto
calibration loop can automatically set the PGA value to
achieve a selected white target level. Each channel also has
a ±4 bit coarse and ±10-bit fine analog offset correction DAC
that allows offset correction before the sample-and-hold amplifier.
These correction values can be controlled by an automated
Digital Black Level correction loop. The PGA and offset
DACs for each channel are programmed independently allowing
unique values of gain and offset for each of the six
channels. A 2-to-1 multiplexing scheme routes the signals to
three 70MHz high performance ADCs. The fully differential
processing channels achieve exceptional noise immunity,
having a very low noise floor of -68.5dB. The 10-bit analogto-
digital converters have excellent dynamic performance
making the LM98620 transparent in the image reproduction
chain.