Comparison of analog front-ends for digital synthetic impedance device

Piezoelectric actuator connected to the digital synthetic-impedance device (DSID) represents a modern approach for vibration damping. For efficient use of DSID there are requirements for low input-to-output time delay and high output impedance of the DSID's main part - the voltage controlled current source. In this paper we present two types of these analogue front-ends. The first discussed circuit is based on the voltage compensation method, while the second on the current compensation method - Howland current pump. We compare directly measured output impedance, input-to-output time delay and also the relative error between synthesized and prescribed impedance. Final part of the article is devoted to discussion of practical aspects of these two implementations. Discussed is the possibility to offset voltage at the output, tolerance of passive elements and options for tuning of the output impedance.