Abstract: A cascode amplifier circuit having substantial linearity, while maintaining other advantages of cascode amplifiers such as relatively high input-to-output isolation and relatively high gain. The cascode amplifier circuit also provides substantially matched impedance between input and output, at least within a selected frequency band, with the effect of providing a circuit that is well-suited for use in a communication system. The cascode amplifier circuit includes feedback loops, such as for example DC feedback loops and AC feedback loops, and bias optimization, with the effect of improving linearity, maintaining gain, minimizing return loss, and providing a relatively high dynamic range.

Abstract: A sub-harmonic mixer having at least one diode ring array used for up-conversion in a transmitter and for down-conversion in a receiver. Each diode ring array has a plurality of (e.g., four) diode rings arranged in parallel. The diode ring array may be connected in parallel or series with the signal flowing in the circuit. In a transmitter, a local oscillator (LO) generates an LO frequency signal. The sub-harmonic mixer generates a signal having twice the LO frequency using the LO frequency signal, and multiplies it to an intermediate frequency (IF) signal to generate a radio frequency (RF) signal for transmission. The sub-harmonic mixer may be a sub-harmonic image rejection mixer having two diode ring arrays (i.e., sub-harmonic mixers) that are coupled together through a 90° hybrid at an input and a 90° hybrid at an output. In a receiver, the sub-harmonic mixer receives an input RF signal and generates an output IF signal in a reverse process.

Abstract: Disclosed are planar structures for coupling electromagnetic signals between planar transmission lines and waveguides. A preferred exemplary structure comprises a shielded patch antenna and one or more capacitive diaphragms disposed adjacent to the patch antenna. This structure is advantageous to MMIC modules in connecting from a planar transmission line of a substrate carrying an MMIC to an external waveguide without the need of a non-planar back metal short, which is normally essential to avoid back scattering from the waveguide and also normally needed to achieve impedance matching. In structures according to the present invention, a patch antenna radiates into the waveguide while the antenna's ground plane reduces back scattering from the waveguide. The one or more capacitive diaphragms provide impedance matching between the microstrip and the waveguide.

Abstract: Disclosed are planar structures for coupling electromagnetic signals between planar transmission lines and waveguides. A preferred exemplary structure comprises a shielded patch antenna and one or more capacitive diaphragms disposed adjacent to the patch antenna. This structure is advantageous to MMIC modules in connecting from a planar transmission line of a substrate carrying an MMIC to an external waveguide without the need of a non-planar back metal short, which is normally essential to avoid back scattering from waveguide and also normally needed to achieve impedance matching. In structures according to the present invention, a patch antenna radiates into the waveguide while the antenna's ground plane reduces back scattering from waveguide. The one or more capacitive diaphragms provide impedance matching between the microstrip and the waveguide.

Abstract: A monolithic microwave integrated circuit (MMIC) semiconductor chip, for use with a hybrid coupler, in a frequency downconverter. The chip has a first input lead for receiving a first combined input signal from the coupler, a second input lead for receiving a second combined input signal from the coupler, and an output lead. Each input signal is a microwave signal combined with a further frequency signal, and one of the microwave and further frequency signals of the first combined signal is out of phase with one of the microwave and further frequency signals of the second combined signal. A single balanced mixer has a first single ended mixer for converting the first combined signal to a first intermediate frequency signal and a second single ended mixer for converting the second combined signal to a second intermediate frequency signal.