A frequency conversion circuit having first and second input signal terminals, and first and second output terminals includes a plurality of non-linear elements, each one having a pair of input electrodes and an output electrode. The first input electrode of each non-linear element is successively interconnected by a two port input coupling means, said input coupling means having a first end coupled to the first input signal terminal and a second end terminated in a terminating impedance. The output electrode of each non-linear device is successively interconnected by a two port output coupling means coupled between the pair of output terminals. An input signal is fed to the first input signal terminal and is coupled to the input coupling means and a portion of such signal is fed to the first input electrode of each non-linear device. Each portion of the input signal is provided with a successive phase shift as it propagates along the input coupling means. The second input signal terminal is fed by a second signal which is fed to the second input electrode of each non-linear element. In response to the pair of input signals, an output signal is provided at the output electrode of each one of said non-linear devices having frequency components equal to the sum and difference of the frequencies of the first and second input signals. In a preferred embodiment, the frequency propagation characteristics of the output coupling means are selected to support propagation of a first one of said sum and difference frequency components of the output signal.
A radio frequency circuit having at least one output terminal includes a plurality of non-linear elements, each having an output electrode. Means are provided for feeding at least one input signal to each one of the non-linear elements. The feeding means includes an electrical pathlength including at least one two port phase shifting element fed by at least the input signal, for providing a plurality of signal portions, each one fed to a corresponding one of the plurality of non-linear elements. These signal portions have a successively increasing phase shift related to the electrical pathlength of the two port phase shifting elements. The output electrodes of each non-linear element are interconnected by an input coupling means including at least one, different, two port phase shifting element, for successively electrically interconnecting the output electrode of each non-linear element. With such an arrangement, by providing two port phase shift elements in the input and output coupling means, proper phasing characteristics may be provided to such circuits without the necessity of using couplers or baluns which are generally difficult to fabricate, particularly, as broadband monolithic microwave integrated circuits.
A matrix mixer includes an amplifier having a plurality of successively coupled transistors and a mixer stage comprised of a plurality of mixer elements successively connected by a common transmission line to output of the plurality of transistors of the amplifier. A matrix provides a circuit having improved gain characteristics and improved isolation between the local oscillator and the input RF signal terminals. Moreover, due to shared transmission lines, smaller circuit sizes is also provided.
A monolithic distributed mixer includes a plurality of dual gate field effect transistors (FETs) and first and second corresponding pluralities of T shaped constant K-filters connected respectively to first and second gates of the dual gate FETs for delaying in time the LO and RF voltages applied thereto whereby the phase shift is the same at each filter and the phase difference between the LO and RF at each FET is equal. Thus, the IF energy developed at each drain is in phase. The plurality of dual gate FETs have their drains commonly connected for summing the IF outputs thereof to provide a flat response throughout the bandwidth which is limited only by the cutoff voltages of the FETs or first and second pluralities of K-filters which act as low pass filters.
An up-conversion mixer includes a first and a second hybrid couplers and a first and a second traveling-wave mixers is disclosed. The first hybrid coupler receives an input intermediate frequency (IF) signal and produces a first IF signal (IF1) and a second IF (IF2) signal, the second IF signal being 180 degree off-phase compared to the first IF signal. The first traveling-wave mixer mixes the first IF signal (IF1) and a first local oscillator (LO1) signal to produces a first radio frequency signal (RF1). The second traveling-wave mixer mixes the second IF signal (IF2) and a second local oscillator signal (LO2) to produces a second RF signal (RF2). The second hybrid coupler to combines the first RF signal and the second RF signal to produce an output RF signal. The use of the traveling-wave mixers allow for a wide bandwidth operation of the up-conversion mixer.
An image rejection mixer including a first and a second hybrid couplers and a first and a second traveling-wave mixers is disclosed. The first hybrid coupler divides an input radio frequency (RF) signal to a first RF signal and a second RF signal, the second RF signal being in quadrature to the first RF signal. The first traveling-wave mixer mixes the first RF signal and a local oscillator (LO) signal to produces a first intermediate frequency (IF) signal. The second traveling-wave mixer mixes the second RF signal and the local oscillator signal to produces a second IF signal. The second hybrid coupler combines the first IF signal and the second IF signal to produce an upper sideband of the IF signals and a lower sideband of the IF signals. The use of the traveling-wave mixers allow for a wide bandwidth operation of the image rejection mixer.
