Improved impedance analyzer with binary excitation signals

The impedance analyzers are widely used to measure, test and validate the properties of the materials, tissues, electrical and electronics networks etc. To make simple power-and cost-efficient device for real-time dynamical measurements in the wide frequency range, special binary waveforms excitation signals can be used, covering the desired spectrum points. Drawback of the using of the binary measurement signals is the presence of the aliased spectrum part in the response signal, giving reasonable measurement error in some cases. In the current paper the solution is proposed, where the measurement error is corrected by the reverse estimation and modeling of the circuit-under-test and the over-all measurement device and system. Examples of the real measurements and improvements are described, for the Piccolo DSP-chip based solution, working in the frequency range from 1 to 500 kHz (15 simultaneous frequencies, with 1 ms output refresh-rate), where the excitation signal is generated by the advanced PWM-unit of the Piccolo-chip and the response signal is acquired by the on-chip 12-bit ADC of the same Piccolo chip and processed on the place. By using of the proposed and described estimation-correction solution the impedance measurement error can be decreased from several tens of ohms till few ohms or even less, if using the fixed 1 kOhm resistor /Zx (measured impedance) voltage divider for the measurement circuit.