Balanced mixer circuit apparatus using two matched integrated circuit field effect transistors as active elements wherein one input signal is applied to the gates of the transistors in push-pull relationship and a second input signal is applied to the substrates of the transistors in a common mode push-push manner. Both input signals thus look into capacitive loads which for practical purposes can be considered to be open circuits, thereby averting any harmonic distortion which might otherwise be produced by loading of the input drive circuits.
A high frequency coil arrangement, comprising an input side coil and an output side coil electromagnetically coupled with each other, the input side coil being divided into two coil elements having substantially equal inductances by provision of a tap, characterized in that two parallel tuner capacitors are provided for the two coil elements for providing two tuner circuits of equal frequencies, and that a further separate capacitor is provided and connected with both ends of the input side coil for adjustment of its tuning frequency.
A transistor circuit is provided with a symmetrical floating configuration for attaining multifunction operation of a transistor having symmetrical source and drain characteristics, preferably a GaAs MESFET. The circuit includes a balun which may be configured as a transformer, a differential amplifier, or a magic-tee waveguide depending on the frequency of signals to be processed by the circuit. Balanced terminals of the balun may be directly or capacitively coupled to source and drain terminals of the transistor. Tuning circuits are employed for applying signals having different frequencies to the transistor and for extracting intermodulation products generated by the transistor in response to the signals at the different frequencies. With the direct connection between the balun and the transistor, alternating voltages may be impressed between the terminals of the transistor to alternate source and drain regions of the transistor. Functions of amplification, modulation, bipolar attenuation, four-quadrant multiplication and correlation, power frequency tripling, and mixing are obtainable. The transistor may be replaced with a pair of transistors connected in series or in antiparallel connection.
Series connected field-effect transistors (FET's) of complementary conductivity types are employed to mix two input signals. The transistors are biased in their linear operating region and operate as common source amplifiers for the signals to be mixed. The input signals are applied to the respective gate electrodes of the transistors and the output signal containing upper and lower sideband frequencies is available at the common drain connection of the transistors.
A frequency converter uses first and second complementary symmetry FET's to perform respective oscillator and mixer functions. The first and second FET's are arranged with respective conduction channels connected in series. The oscillator function is performed by the first FET via feedback provided between its source or drain electrode to its gate electrode. The mixer function is provided by the second FET via an input circuit coupling an input signal to its gate electrode. Sum and difference beat frequencies are available at the circuit node interconnecting the conduction channels of the first and second FET's.
An electronic control device using a field effect transistor (f.e.t.) of a particular design and capable of causing in a h.f. circuit a phase shift appreciable at a frequency of the order of several Gc/s. To this effect, in a f.e.t. formed by an active layer of a thickness a deposited onto a semiconductor substrate of high resistivity, the gate of the f.e.t. is longer than the thickness a for instance the length of the gate measured along the path of the charge carriers in the conductive channel is of 10 microns, giving an appreciable phase shift at an operating frequency of 10 Gc/s.
