A New Technique for the Direct Measurement of Y-Parameters at Microwave Frequencies
A technique has been developed which makes practical the direct measurement of active device two-port y-parameters at microwave frequencies. The instrumentation involved is a simple modification of a conventional s-parameter test set, and the measurement procedure is only slightly more complicated than in a conventional s parameter measurement.
Large Signal GaAs MESFET Oscillator Design
Techniques for large signal GaAs MESFET oscillator design are described which do not require repeated large signal measurement. In the first technique, small signal S-parameter measurements are used with a computer program to compute the packaged and mounted device equivalent circuit. Large signal measurements are made to determine a mathematical relationship between only those parameters which vary under large signal conditions. These relationships are included in the computer program. Then, once the equivalent circuit has been computed from the small signal S-parameter measurements, those parameters varying under large signals are incrementally altered until large signal S parameters are obtained which correspond to maximum oscillator output power. These values are used to calculate embedding element values for six oscillator topologies. A coaxial cavity FET oscillator was built and tested using the large signal design theory, and it substantially verified the design technique. The second design technique is based on the fact that S/sub 21/ varied more than other S parameters under large signals. By making design calculations based on S/sub 21/ reduced to the point corresponding to maximum oscillator power, it was possible to get usable design information for an FET oscillator.
On Oscillator Design for Maximum Power
A method of oscillator design that maximizes the output power is presented. The embedding network is derived from a set of four linear algebraic equations. The method is applicable to the class of nonlinear elements whose single frequency largesignal parameters depend on a single port voltage.