1 Features
• 256 channels
• On-chip, 16-bit ADC
• High performance:
– Noise: 440 electrons RMS
(1.2-pC input charge range)
– Low correlated noise
– Full-channel integral nonlinearity:
±2 LSB at 16 bit
– Scan time: < 16 μs to 204.8 μs
• Integration:
– Programmable full-scale input charge range:
0.3 pC to 12.5 pC with resolution of 0.3 pC
– Internal timing generator (TG)
– Built-in correlated double sampler
– Software programmable electron or hole
integration mode
– Pipelined integrate-and-read for improved
throughput—data-read during integration
– Serial LVDS output
– On-chip temperature sensor
• Simple power supply scheme:
– Single 1.85-V power supply operation
• Multiple power modes with power consumption
ranging from 1 mW/ch to 2 mW/ch
• Power-down modes: sleep and standby
• Binning mode support
• Custom chip-on-film (COF) packages

2 Applications
• Flat-panel, X-ray detectors
• Charge detectors
• Capacitance measurement

3 Description
The AFE3256 is a 256-channel, analog front-end
(AFE) designed to suit the requirements of flat-panel
detector (FPD) based digital X-ray systems. The
device includes 256 integrators, correlated double
samplers (CDSs) with dual banking, and 256:2 analog
multiplexers. The device also features two 16-bit
successive-approximation register (SAR) analog-todigital
converters (ADCs). Serial data from the ADCs
are available in low-voltage differential signaling
(LVDS) format.
The device, also commonly referred as a readout
integrated circuit (ROIC), optimizes the overall system
performance using features such as multiple power
modes and in-system debug options.
The sleep and standby modes enable substantial
power saving which is critical for battery-powered
systems.