8bits, 200Msps Sub-Ranging Flash AD Converter

CT22501 is a dual stage sub-ranging 8bits ADC which is able to operate at 200MSps.

The conversion is thus carried out in 2 stages. The 4 most significant bits (MSBs) results from the operation of a Coarse Flash ADC. Its outputs are feed to a DAC in order to generate the inputs for the Fine Flash ADC (FADC) depending both on the input signal to be converted and on the results of the first part of the conversion.

The flash ADCs are implemented using dynamic latched comparators, in order to minimize static/DC power dissipation. In order to improve accuracy, self-calibration of the FADCs is employed. A redundant FADC is implemented so that calibration can be performed in background without stopping conversion, and is in power down while not converting and not performing calibration. Conversion takes 2 clock cycles.

CT22501 features a track and hold circuit that samples the input signal and feeds it to the flash ADCs.