Super heterodyned power detector with enhanced linearity for use in power leveling loops

An adjustable gain power leveling detector wherein the leveling detector receives an output signal from a directional coupler, the leveling detector comprising:

• a local oscillator and a frequency converter for producing a signal whose amplitude is proportional to the amplitude of the output signal from the directional coupler and whose frequency is equal to a fixed intermodulation IF frequency,
• a low noise amplifier;
• a frequency splitter for providing two signals, a first signal and a second signal, each of which is proportional to the input signal;
• the low noise amplifier amplifying the IF frequency sufficiently to compensate for losses in the frequency splitter which injecting as little noise as possible;
• a programmable gain amplifier for amplifying the first splitter signal by a programmable gain factor;
• a band pass filter for band pass filtering the amplified programmable gain amplifier signal;
• a narrow band power detector for providing a stable DC output voltage signal for an input of a single power at the IF frequency;
• a low pass filter for removing residual IF signal from the DC output of the power detector;
• a linear IF detector for linearly calibrating the second splitter signal over a wide range of signal levels;
• a power control algorithm for setting the gain to an appropriate level to give desired power at an RF output.

In an adjustable gain power leveling detector wherein the leveling detector receives an output signal from a directional coupler, the method comprising:

• producing a signal whose amplitude is proportional to the amplitude of the output signal from the directional coupler and whose frequency is equal to a fixed intermodulation IF frequency,
• providing a stable DC output voltage signal for an input of a single power at the IF frequency;
• and
• maintaining the power detector DC voltage signal substantially constant.