Automatic level control circuit for local oscillator signals with the lever control signal being derived from the DC current present in the diode circuit of an MIC frequency mixer

An automatic level control circuit for local oscillator signals coupled to frequency mixers comprising:

• a first source of radio frequency signals;
• a second source of local oscillator signals;
• a frequency mixer including a hybrid junction coupled to said first source and a circuit having a pair of series connected diodes therein coupled to said hybrid junction;
• first means coupled to said circuit to derive a level control signal from the direct current flowing in said circuit;
• and
• second means coupled to said second source, said hybrid junction and said first means, said second means being responsive to said control signal to maintain said local oscillator signals coupled to said hybrid junction at a selected constant level.