Class-A Amplifier Analysis: High Frequency Approximation
In order to estimate the gain losses of a high frequency class-E amplifier versus a class-A amplifier, using the same device (MRF182), at the same frequency (100 MHz), output power level [P.sub.OUT] (20 W) and supply voltage [V.sub.DC] (24 V), two amplifiers have been designed and simulated: a class-A power amplifier and a class-E amplifier with square voltage drive.
Much literature exists, covering small-signal class-A amplifier analysis and design.
Class-A Amplifier Analysis: Low Frequency Approximation
(8) Figure 3 shows the schematic of the class-A amplifier under analysis.
The typical value of third-order intermodulation distortions for many microwave high power class-A amplifiers when operated near saturation is approximately -22 dBc or worse.
Class-AB amplifiers, especially those using laterally diffused metal oxide semiconductor transistors, are more DC efficient compared to class-A amplifiers. The intermodulation performance of these amplifiers usually is good when they are operated backed off 3 dB or more, making them good candidates for applications requiring moderate intermodulation performance.
However, two class-A amplifiers were chosen as the main and error amplifiers because of their ready availability.