The S-probe-a new, cost-effective, 4-gamma method for evaluating multi-stage amplifier stability

The authors describe a generalized, automated, noninvasive, 4-gamma technique for stability analysis of multistage active circuits. It operates directly in the circuit simulator environment and eliminates all off-line calculations. This technique can be extended to n-port networks and works equally well with circuit models or S-parameter descriptions. Most importantly, it can detect special cases of instability involving active terminations. These are often missed using conventional stability analysis approaches.<>