A low power high speed readout circuit for 320×320 IRFPA
A low power high speed Readout Integrated Circuit(ROIC) design for 320 × 320 IRFPA is proposed in this paper. The ROIC operates as follows: after integration phase, voltages on column bus of odd rows and even rows are read out alternately. And the results are sampled and stored alternately on two sample capacitors added at the output point of column CSA. When sample capacitor for odd row samples and holds data, sample capacitor for even row works as feedback capacitor of output buffer so that voltage stored on sample capacitor can be read out directly. In this design, each column has one low power charge amplifier, and output buffer's power is optimized. Besides, capacitance of sample capacitor is much larger than that of CSA's feedback capacitor, so the KTC noise is lower and the charge injection is suppressed while the output range is not impaired. This design is also applicable to window readout. The readout speed can reach 8MHz with power consumption lower than 50mW. A 320 × 320 ROIC with pixel size of 30 × 30 µm2 has been designed and fabricated with a 0.35 µm DPTM CMOS process under 5v supply voltage.