Abstract: A wireless instrument and methods for the remote monitoring of a plurality of biological parameters is described. The instrument includes a means of receiving data from a plurality of sensors, a means for converting the sensor data to a digital format, a means for collating the digitised sensor data into a single digital data stream, a transmitter for modulating a carrier signal with the digital data stream to create a modulated signal suitable for wireless transmission, an antenna for generating a radiating electromagnetic field to be received by a remote receiver, and an electrical power source. In a further embodiment, an additional means is provided for including an identification code in the transmitted digital data stream. In a further embodiment, an additional means is provided for monitoring operational parameters of the instrument and the inclusion of the monitored operational parameters in the transmitted digital data stream.

Abstract: A low-noise, linearized double-balanced active mixer circuit is described, including a first input for a local oscillator (LO), a second input for an intermediate frequency (IF) signal, and an output for a resulting product radio frequency (RF) signal. The mixer circuit also includes a feedback transformer circuit for the purpose of improving the intermodulation (IM) performance. The lossless nature of the feedback topology gives the active mixer a lower noise figure (NF) characteristic than is realizable with conventional methods. The number of active devices is minimized in order to ensure that the mixer attains the lowest possible NF.

Abstract: A low-noise, linearized double-balanced active mixer circuit is described, including a first input for a local oscillator (LO), a second input for an intermediate frequency (IF) signal, and an output for a resulting product radio frequency (RF) signal. The mixer circuit also includes a feedback transformer circuit for the purpose of improving the intermodulation (IM) performance. The lossless nature of the feedback topology gives the active mixer a lower noise figure (NF) characteristic than is realizable with conventional methods. According to a further embodiment, the mixer circuit includes an additional pair of complementary amplifier transistors for the purpose of further improving the IM performance.

Abstract: An augmented common-base transistor amplifier circuit is described, including an input terminal and an output terminal. The amplifier circuit also includes an augmentation circuit, connected from the emitter to the base of the amplifying transistor, which detects an error voltage at the transistor emitter, amplifies and inverts the error voltage, and then applies the amplified error voltage to the base of the amplifying transistor, for the purpose of reducing the emitter error voltage and thus linearizing the common-base amplifier. According to a further embodiment, a second transistor is used for amplifying the emitter error voltage, and a further embodiment uses a transformer for augmentation. Circuits are described for single-ended, push-pull, and complementary amplifiers.

Abstract: A low-noise, linearized double-balanced active mixer circuit is described, including a first input for a local oscillator (LO), a second input for an intermediate frequency (IF) signal, and an output for a resulting product radio frequency (RF) signal. The mixer circuit also includes a feedback transformer circuit for the purpose of improving the intermodulation (IM) performance. The lossless nature of the feedback topology gives the active mixer a lower noise figure (NF) characteristic than is realizable with conventional methods. The mixer circuit further includes an augmentation circuit for correcting the non-linear input resistance of the common-base transistor amplifier. According to a further embodiment, the augmentation circuit includes a common-emitter transistor amplifier circuit. According to a further embodiment the augmentation circuit includes a positive-feedback transistor amplifier circuit. According to a further embodiment the augmentation circuit includes a two-winding transformer.

Abstract: A lossless feedback transistor amplifier circuit is described, including an input terminal and an output terminal, for the purpose of amplifying a signal voltage. The amplifier circuit also includes an augmentation circuit, connected from the emitter to the base of a common-base amplifying transistor, which detects an error voltage at the common-base transistor emitter, amplifies and inverts the error voltage, and then applies the amplified error voltage to the base of the common-base amplifying transistor, for the purpose of reducing the emitter error voltage and thus reducing the harmonic and intermodulation distortion of the lossless feedback amplifier. According to a further embodiment, a second transistor is used for amplifying the emitter error voltage. In a further embodiment, an inverting positive feedback amplifier is used for amplifying the emitter error voltage. In a further embodiment, a transformer is used to amplify and invert the emitter error voltage.

Abstract: A linearized double-balanced active mixer circuit is described, including a first input for a local oscillator (LO), a second input for an intermediate frequency (IF) signal, and an output for a resulting product radio frequency (RF) signal. The mixer circuit also includes a feedback circuit, along with a pair of operational amplifiers, for the purpose of improving the intermodulation (IM) performance. According to a further embodiment, the mixer circuit includes a series-shunt feedback amplifier in place of the operational amplifier, and a further embodiment includes an additional pair of transistors to further improve the IM performance. The output of the mixer circuit includes a signal combining circuit, composed of either a network of resistors having two output terminals, or two transformers having a common output terminal.