Efficient nonlinear Stability Analysis of Microwave Circuits using Commercially Available Tools

Abstract

In this paper, two techniques for checking stability of multi-transistor MMIC circuits are analyzed. The two approaches allow both linear and nonlinear stability analysis of any complex circuit fed by small or large signals. The agreement found gives a unified way to propose a fast and efficient tool to ensure stability of a design during the design step using commercially available software. An example is given to evidence the suitability of the approach. It concerns a MMIC HBTpower amplifier, which exhibited afrequency division phenomena that has been detected by simulations and confirmed by measurements.

Detecting and avoiding odd-mode parametric oscillations in microwave power amplifiers

“…Indeed, the presence of complex-conjugate poles with a positive real part in H n (s) indicates the start-up of a spurious oscillation with increasing amplitude. In doing so, a parametric frequency division has been detected during simulation of the X-band power amplifier, thus confirming the experimentally observed behaviour [9,10].…”

“…The stability of this amplifier has been studied in [10] using different large-signal stability analysis methods [8,11]. Here, the approach proposed in [8] for stability analysis of the large-signal steady-state solutions obtained with harmonic balance is extended.…”

“…In this article, a technique for predicting the nature of parametric oscillations is applied to the detection of various odd-mode oscillations in two monolithic power amplifiers, each having a different topology. Firstly, an X-band amplifier, already analyzed in [9,10], is used to describe the bases of the technique. Then the technique is extended to the analysis of a novel example (L-band amplifier) having a different topology and oscillation mode, in order to demonstrate the general validity of the procedure.…”

Sensitivity Enhancement in Pole-Zero Identification Based Stability Analysis of Microwave Circuits

“…2 can be analyzed connecting a voltage source in series at the same probe point. To illustrate the benefits of this approach, the dual I-V probe is applied to an f0l2 parametric oscillation in an X-band multi-stage MMIC power amplifier [3] and to a bias oscillation in a medium power FET amplifier built in hybrid microstrip technology. In the case of the MMIC amplifier the dual I-V probe has been connected to the collector of one of the output stage transistors as it is shown in Fig.…”

43W, 52% PAE X-Band AlGaN/GaN HEMTs MMIC Amplifiers

“…The simulation of the stability of these amplifiers was first performed in linear operation mode at the quiescent biasing point. Then, the non linear stability was analyzed at high input power level [6]. S 11 and S 22 are better than -7dB in the [8.5-10.5] GHz bandwidth.…”