A Micro-phase Difference Measurement Circuit Using 4-bit Input Stage

This paper presents a transimpedance amplifier (TIA) used as a micro-phase difference measurement circuit for real-time monitoring of urine volume in the bladder. The proposed TIA consists of an input transconductance amplifiers (TCAs) and feedback TCAs. TIA requires adjustment of output amplitude when measuring micro-phase differences. The output amplitude is adjusted using the input transconductance of the input TCA. The transconductance of the input TCAs is adjusted using a 4-bit input stage whose transconductance can be changed by 4 -bit and the gate voltage $V_{\text {cont }}$ of a MOS connected in parallel with the 4-bit input stage. The power consumption of the proposed circuit is $910 \mu \mathrm{W}$ when supplied with a 5 V voltage and the circuit area is $0.182 \mathrm{mm}^{2}$. The results of measuring the micro phase difference with the proposed circuit showed an error rate of 0.160% for the same input signal amplitude and an error rate of 1.72% for a 1 mV difference in input voltage amplitude.