Patent ID: 7553152

Claim:
An electronic circuit for generating a trapezoidal excitation waveform, comprising: a controllable frequency source configured to generate a square wave having a frequency that, upon energization of the controllable frequency source, decreases from an initial frequency value to a substantially constant frequency value a time period after energization of the controllable frequency source; and a trapezoidal waveform generator coupled to receive the square wave and operable, in response thereto, to generate a trapezoidal waveform at least when the square wave frequency attains the substantially constant frequency value, the trapezoidal waveform generator comprising: an integrator circuit coupled to receive the square wave and operable, in response thereto, to supply an integrated waveform, the integrated waveform having peak positive and negative voltage amplitude values, and a wave shape that is a mathematical integral of the source waveform over time; and a clipper circuit coupled to receive the integrated waveform and operable, in response thereto, to limit the peak positive and negative voltage amplitude values to predetermined positive and negative values, respectively.