Fully Integrated Mixed Mode Interface Circuit in 65 nm CMOS for Leukemia Detection and Classification

Abstract

Lab on a Chip (LOC) applications are taking the world by storm. This paper proposes a mixed mode interface circuit for LOC applications for Bioimpedance measurement. The interface circuit consists of a low noise instrumentation amplifier and an analog to digital converter. The proposed interface circuit utilizes the benefits of both current mode and voltage mode circuits. The design of the instrumentation amplifier uses a second-generation current conveyor to provide the low noise and high gain required to acquire the weak signal from the electrodes. The IA provides a maximum gain of 55.6 dB with 2 MHz bandwidth. A second order Sigma Delta Modulator with a maximum sampling rate of 128 MS/s provides the output digital bit stream capable of reaching a resolution of 11 bits for an input sinusoidal with 50 kHz frequency. The use of a buffered comparator allows the relaxation on the slew rate requirement while maintaining a high sampling rate. The full system power consumption is 5.5 mW with a chip area of only 0.0153 mm2.