A Cost-Effective Angle Demodulator IC for Path Matched Differential Interferometry Based Sensors

Abstract

The angle demodulator (ADM) is a key component for the path matched differential interferometry (PMDI) sensors. Conventional ADMs require tens of operational amplifiers (OPAMPs) and bulky capacitors and resistors, making them diflicult to be realized as integrated circuits (ICs). This paper presents the first ADM IC design that requires only one OPAMP and thus saves significant area and power. In addition, this novel ADM design tolerates a wide range of modulation depth of the optical interferometer of the PMDI sensors. As a result, the yield of the PMDI sensor significantly increases. A test chip has been designed and successfully verified in 0.18-mu m CMOS. The active area of the proposed circuits is only 476 by 368 mu m(2) and it consumes only 6.26 mW.