High efficiency photoconductive semiconductor switch-based amplifier for high power microwave transmission
Power amplifier apparatuses and techniques for optimizing the design of power amplifiers are disclosed. In one aspect, a method for optimizing a power amplifier includes selecting a circuit topology for the power amplifier. The circuit topology includes one or more photoconductive switches and an impedance matching network including one or more parameter values representative of the impedance matching network or the photoconductive switches that can be adjusted. The method further includes selecting one or more optimization goals for the impedance matching network and the one or more photoconductive switches, and adjusting the one or more parameter values according to the one or more optimization goals. The one or more optimization goals include an efficiency at a particular power output.
1. A method for optimizing a power amplifier, comprising:
selecting a circuit topology for the power amplifier including one or more photoconductive switches and an impedance matching network including one or more parameter values representative of the impedance matching network or the photoconductive switches that can be adjusted;
selecting one or more optimization goals for the impedance matching network and the one or more photoconductive switches; and
adjusting the one or more parameter values according to the one or more optimization goals, wherein the one or more optimization goals comprise an efficiency at a particular power output.
2. The method of claim 1 , wherein the circuit topology includes one or more circuit locations for the one or more photoconductive switches and the impedance matching network includes one or more matching stubs, one or more transmission lines, and one or more lumped or distributed matching structures.
3. The method of claim 1 , wherein the one or more parameter values include at least one of:
a transmission line length;
a transmission line impedance;
a matching stub length, matching stub location, or matching stub impedance;
a lumped element value; or
a distributed element impedance.
4. The method of claim 1 , wherein the one or more parameter values include a switch capacitance, a switch inductance, and a conductivity as a function of time for the one or more photoconductive switches.
5. The method of claim 1 , wherein the one or more optimization goals further comprise:
a gain,
a linearity, or
a bandwidth.
6. The method of claim 1 , wherein the adjusting comprises:
determining an impedance of the impedance matching network at a fundamental frequency and a plurality of harmonics of the fundamental frequency;
determining a conductivity for each of one or more photoconductive switches at the fundamental frequency and the plurality of harmonics; and
determining an output voltage and a power amplifier power consumption using a harmonic balance approach.
7. A method for optimizing a power amplifier, comprising:
determining an impedance of an impedance matching network at a fundamental frequency and a plurality of harmonics of the fundamental frequency, the impedance matching network belonging to a circuit topology of the power amplifier that further includes one or more photoconductive switches;
determining a conductivity for each of the one or more photoconductive switches at the fundamental frequency and the plurality of harmonics;
determining an output voltage and a power amplifier power consumption using a harmonic balance approach; and
adjusting one or more parameter values representative of the impedance of the impedance matching network, the conductivity for each of the one or more photoconductive switches, the output voltage, or the power amplifier power consumption according to one or more optimization goals.
8. The method of claim 7 , wherein the circuit topology includes circuit locations for the one or more photoconductive switches and the impedance matching network includes one or more matching stubs, one or more transmission lines, and one or more lumped or distributed matching structures.
9. The method of claim 7 , wherein the one or more parameter values include at least one of:
a transmission line length;
a transmission line impedance;
a matching stub length, matching stub location, or a matching stub impedance;
a lumped element value; or
a distributed element impedance.
10. The method of claim 7 , wherein the one or more photoconductive switches is characterized by a switch capacitance, a switch inductance, and a conductivity as a function of time.
11. The method of claim 7 , wherein the one or more optimization goals include one or more of an efficiency at a particular power output, a gain, a linearity, or a bandwidth.
12. A microwave power amplifier, comprising:
one or more photoconductive switches;
an optical source carrying an optical signal coupled to the one or more photoconductive switches, wherein the optical signal is transformed to an electrical signal by the one or more photoconductive switches; and
an impedance matching network comprising a plurality of circuit elements connected with the one or more photoconductive switches in a circuit topology, wherein one or more parameter values characterize at least a portion of the circuit elements and the one or more photoconductive switches, and wherein the one or more parameter values are selected to achieve one or more optimization goals.
13. The microwave power amplifier of claim 12 , wherein the circuit topology includes circuit locations for the one or more photoconductive switches and the impedance matching network includes one or more matching stubs, one or more transmission lines, and one or more lumped or distributed matching structures.
14. The microwave power amplifier of claim 12 , wherein the one or more parameter values include at least one of:
a transmission line length;
a transmission line impedance;
a matching stub length, a matching stub location, or a matching stub impedance of a stub tuner of the microwave power amplifier;
a lumped element value; or
a distributed element impedance.
15. The microwave power amplifier of claim 12 , wherein the one or more parameter values include a switch capacitance, a switch inductance, and a conductivity as a function of time for the one or more photoconductive switches.
16. The microwave power amplifier of claim 12 , wherein the one or more optimization goals include one or more of an efficiency at a particular power output, a gain, a linearity, or a bandwidth.
17. The microwave power amplifier of claim 12 , wherein the one or more optimization goals is achieved by:
determining an impedance of the impedance matching network at a fundamental frequency and a plurality of harmonics of the fundamental frequency;
determining a conductivity for each of one or more photoconductive switches at the fundamental frequency and the plurality of harmonics;
determining an output voltage and a power amplifier power consumption using a harmonic balance approach; and
adjusting the one or more parameter values according to the one or more optimization goals.
18. The microwave power amplifier of claim 14 , wherein the stub tuner is a radial stub tuner, a bowtie stub tuner, or a butterfly stub tuner.