Oscillation with Negative Impedance

TL;DR

This paper provides a theoretical analysis of oscillation phenomena using negative impedance circuits with active and passive components, focusing on their resonant frequencies and modulation capabilities.

Contribution

It introduces a comprehensive circuit analysis of negative impedance oscillators using cross-coupled transconductance pairs and passive components, expanding understanding of their oscillation behavior.

Findings

Negative impedance can be negative resistance, inductance, or capacitance.

Oscillation occurs when negative impedance supplies energy to passive components.

Resonant frequency can be modulated by passive RLC components.

Abstract

Oscillation and frequency modulation have been leveraged for applications in detection (or sensing), data processing, and telemetry. This work provides a theoretical analysis of oscillation phenomena with negative impedance implemented using a cross-coupled transconductance pair. The negative impedance can consist not only of a negative resistance but also of a negative inductance and a negative capacitance, where the negative resistance supplies energy to the inductance and capacitance, causing oscillation at a resonant frequency. Also, the resonant frequency can be modulated by combining with passive components such as a resistor, an inductor, and a capacitor. In this work, a comprehensive circuit analysis employing small-signal models and transfer functions is performed to understand the oscillation phenomena and resonant frequencies arising from a combination of active and passive RLC circuits, in which the active RLC circuit is modeled as a negative impedance and implemented using a cross-coupled transconductance pair.