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Synthesis of a digitally controlled impedance element
R Kleffel1, I D Schneider, D Jennings
1Electronics Division, Cardiff School of Engineering, UK.
Medical & Biological Engineering & Computing
|September 14, 2000
Summary
This study presents a digitally controlled electrical impedance element with a wide impedance range (1:1000) and stability up to 1.5 MHz using negative k values. Positive k values offer limited range and stability below 100 kHz.
Area of Science:
- Electrical Engineering
- Circuit Design
- Materials Science
Background:
- Developing digitally controlled electrical components is crucial for modern electronics.
- Existing impedance elements often have limitations in range, stability, or frequency response.
Purpose of the Study:
- To present a practical design for a digitally controlled electrical impedance element.
- To analyze the impact of a gain factor (k) on the element's performance and stability.
- To validate circuit models with practical measurements.
Main Methods:
- A novel circuit design incorporating a real impedance element in series with a voltage source controlled by a factor k.
- Experimental measurements to assess impedance range, stability, and frequency response.
- Comparative analysis of performance with positive and negative k values.
Main Results:
- Negative k values enabled a 1:1000 controlled impedance range and stability up to 1.5 MHz with low source impedance.
- Positive k values provided a restricted impedance range and stability only up to 100 kHz.
- Strong correlation observed between circuit models and practical measurements.
Conclusions:
- The digitally controlled impedance element demonstrates significant potential, particularly with negative k values for high-frequency applications.
- Further optimization of the multiplier is needed to extend the operational frequency range to low megahertz.
- The design offers a versatile solution for applications requiring tunable impedance.