Abstract: A bi-directional amplifier having two symmetrical and versatile impedance matching circuits with a JFET therebetween, and a method for bi-directional amplification using a JFET. Each junction of the JFET may be a drain or a source depending on the direction of amplification. Each impedance matching circuit provides a low impedance for the junction that is a source and a high impedance for the junction that is a drain. The impedance is varied by adding a first capacitor parallel to a resonating inductor and a second capacitor, which is removed or inserted in series with the load, responsive to the direction of amplification. The frequency of the signal being amplified may be different for each direction.

Abstract: A singly-balanced active mixer circuit is disclosed for developing an IF signal by combining an RF signal and a local oscillator (LO) signal. The RF and LO signals are applied to a strip transmission line ring which provides balanced components of the LO signal to a pair of active devices arranged in an singly-balanced active mixer. The active devices are coupled directly, or via a balanced PI-network to the primary winding of an output transformer for application to the following IF stage of the radio receiver. DC biasing of the active devices is provided via a floating tap on the primary winding of the output transformer which is not bypassed at the input, LO and IF frequencies. The singly balanced active mixer circuit may be advantageously utilized in a radio having a receiver with broadband front-end RF selectivity.

Abstract: A singly-balanced active mixer circuit is disclosed for developing an IF signal by combining an RF signal and a local oscillator (LO) signal. The RF and LO signals are applied to a strip transmission line ring which provides balanced components of the LO signal to a pair of active devices arranged in a singly-balanced active mixer. The active devices are coupled directly, or via a balanced PI-network to the primary winding of an output transformer for application to the following IF stage of the radio receiver. The singly balanced active mixer circuit may be advantageously utilized in a radio having a receiver with broadband front-end RF selectivity.