Time-of-flight distance sensor with MOSFET lowpass filter as key element for suppression of ambient light |
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| Authors: | Zach G. Zimmermann H. |
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| Affiliation: | Microwave and Circuit Engineering, Vienna University of Technology, Institute of Electrodynamics, Vienna, Austria; |
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| Abstract: | A lowpass filter consisting of small MOSFET transistors is presented for application in a time-of-flight distance sensor. As a decisionmaking element, it activates the mechanism for background-light suppression in combination with some logic components. The cutoff frequency around 1 MHz is designed to smooth a signal with 10 MHz ripple. A filter attenuation of -35 dB/decade is achieved at smaller area compared to an RC-filter of only first order in the used 0.6 μm BiCMOS technology. The functionality is proven by distance measurements up to 150 klx of extraneous light with centimetre accuracy, exceeding the performance of existing sensors. |
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