Receiver input stage with an improvement of the signal to noise ratio

A receiver input stage comprising:

• an upper sideband parametric degenerated down converter for converting a high frequency input signal into an intermediate frequency signal;
• demodulating means having a signal input;
• a controllable oscillator connected in a control loop with said converter and said demodulating means for supplying said converter with a pump signal which follows the intermediate signal in frequency and phase and which has a frequency equal to twice the intermediate frequency such that the sum of the pump signal frequency and the intermediate frequency equals three times the intermediate frequency;
• and means for terminating said converter, connecting the output of said converter to said demodulating means signal input, and defining a real resistance at the converter reflective frequency, where the reflective frequency is the difference between the pump signal frequency and the intermediate signal frequency whereby said circuit has an available power gain greater than unity and an improved signal to noise ratio for the intermediate frequency signal at said signal input of said demodulating means.