Noise and Power efficient source follower per detector unit cell for readout integrated circuits of photodiode sensor arrays

Abstract

In this work, an interface circuit for readout integrated circuit (ROIC) has been proposed employing source follower per detector (SFD) unit cell and current mirror integration (CMI) in order to have high performance with less circuit complexity. In terms of complexity, SFD unit cell is a good choice because it has three only transistors and less complexity. SFD is a simple interface topology for high density and low power ROICs. The SFD unit cell has disadvantage of instable detector bias voltage that makes it non-linear and increases the noise factor at the output side. The interfaced approach has been proposed here to combine the two basic unit cells. To reduce the noise factor at the output side here SFD is interfaced with the current mirror integration unit cell. It is shown here that the noise performance improves by about 98.93% with respect to the conventional SFD unit cell. The proposed circuit shows 18.18% degradation in power after simulation. Cadence 180 nm technologies have been used for the simulations/calculations.