GB875420A - Parametric amplifier - Google Patents

Abstract

875,420. Parametric amplifiers. MULLARD Ltd. June 3, 1960, No. 19762/60. Class 40 (9). A parametric amplifier comprises three independently tunable resonant circuits coupled together so as to have a portion common to the three circuits, said common portion including a voltage-dependent reactor, each resonant circuit having independent tuning means located outside the common portion. As shown the common portion consists of a junction of three coaxial lines G, H, J, a voltage dependent capacitor, such as a diode (not shown) being connected between the inner and outer conductors at the common point. The pump frequency (6 Gc/s.) is fed into a waveguide P tunable by the capacitative probe B and thence to the coaxial line G whose centre conductor extends into the guide as a probe. The cut-off frequency of the guide is sufficiently high that the signal and idler frequencies (2.8 and 3.2 Gc/s.) are reflected therefrom. The signal frequency is applied to a waveguide S tunable by the probe A, and thence by a band-pass filter E, which rejects the pump and idler frequencies. Coaxial line I tunable by the short-circuiting plunger C resonates at the idler frequency, the filter F which rejects the signal and pump frequencies connecting it to the coaxial line J. The waveguides may be replaced by coaxial lines provided that a suitable filter is included in the case of P.