Design and construction of a high voltage piezoelectric transducer driver
Abstract
Piezoelectric transducers (PZT) are important devices used in laser research. Their stable oscillatory linear motion provides the necessary controlled variations in optical path lengths particularly in experimental setups requiring a Michelson Interferometer. Another important application of PZTs is the cavity tuning of a Fabry-Perot resonator. The mirror mounted on a PZT oscillates along the laser axis at a frequency around the atomic center line frequency in the gain curve. Maximum intensity is attained if the cavity length is at a certain value such that an atomic line froqucncy is contained in (and is supported by) the gain curve. In this case, a single cavity mode oscillates. On the other hand, the intensity approaches a minimum at other cavity lengths if there is no line frequency within the gain curve.
One major difficulty of their use is its high voltage requirement to produce any significant oscillatory motions. In some PZTs, the voltage retirement is at least 500 to 700 volts. In this paper, we present the design of a low-power PZT driver capable of generating high voltage levels of triangular and ramp waveforms. The PZT driver functions as a high voltage amplifier capable of producing 1,000 volts peak-to-peak (Vp-p) triangular and ramp waveforms. The circuit consists of two MOSFETSs with a breakdown voltage of 1 kV and 2 Amperes. MOSFET1 was used as a common-source inverting amplifier driving MOSFET2 which was configured as a source follower. The npn transistor (Ql) used in the circuit was a low voltage device that floats on the output. The operational amplifier (OP-AMP1) served as a feedback mechanism which makes the overall amplifier circuit linear. The input signal to OP-AMP1 was a variable frequency low-voltage (0-12 Vp-p) triangular or ramp signal. This was the same frequency which controls the frequency of vibration of the PZT. The amplitude of the high voltage signal is proportional to the low voltage signal such that the former was controlled by adjusting the amplitude of the latter.
