Hewlett-packard Company

Knud L Knudsen

Thomas Hornak

An image-rejecting receiver comprises a tunable mixer stage, a time-share I-Q mixer stage, a complex filter, and an image rejector. The time-share I-Q mixer stage includes a switch assembly, inphase and quadrature polarity inverters, and a clock generator. The switch assembly generates pulses and distributes them in alternation to the polarity inverters. Performing distribution prior to polarity inversion preserves the orthogonality of the inphase and quadrature target signal components despite pulse-to-pulse bleeding. Charge accumulated at the distributor switch input is dumped between pulses to further minimize such bleeding. A current-mode field-effect-transistor implementation ensures unity gain across each polarity inverter so that they are gain-matched. Gain matching and preservation of orthogonality optimize the conditions for the complex filter to attenuate and for the image rejector to cancel an image signal. The polarity inverters are switched in quadrature to relax polarity-inverter transition timing tolerances, decreasing costs and increasing reliability.

Time-share I-Q Mixer system with distribution switch feeding in-phase

A method and apparatus for maintaining stability while substantially compensating an output signal of a high gain, wide band amplifier having an undesirable signal dependent offset voltage, generated by signal dependent self heating of circuit components. A thermal offset voltage generator producing a signal dependent thermally generated offset voltage similar to that of the wide band amplifier is provided. The input of the thermal offset voltage generator is coupled an output of the wide band amplifier. The output of the thermal offset voltage generator is amplified and low pass filtered to provide a filtered compensating signal. The filtered compensating signal is injected into the wide band amplifier so as to substantially compensate an output signal of the wide band amplifier for the signal dependent thermally generated offset voltage of the wide band amplifier.

Method and apparatus for compensating thermal time constants in an

A high speed charge-coupled sampler and rate reduction circuit is disclosed. The present invention allows measurement of high frequency input signals while reducing actual data rates for a series of accurately interleaved sampler data streams. The charge-coupled sampler includes a source means for providing a steady supply of charge and a sampling gate means adjacent to the source means for dividing the charge stream into discrete charge packets separated uniformly in time. An input gate means, adjacent to the sampling gate means, modulates the discrete charge packets, such that size of each charge packet is directly proportional to the instantaneous voltage applied to the input gate means. A plurality of sequential charge output means in turn surround and are adjacent to the input signal gate means. Each sequential charge output means comprises a transfer gate and a storage gate for transferring and storing the charge packet modulated by the input gate means. Once a charge packet is stored by storage gate, it is available for further processing as part of that particular data stream. By interleaving the data streams from all sequential charge output means, the original input signal may be reconstructed. The high speed charge-coupled sampler and rate reduction circuit disclosed and claimed in this patent application provides an advanced, highly accurate and compact instrument for high frequency data acquisition and processing.

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Mountain View, CA, United States of America

Knud L Knudsen