127 results about "Constant impedance" patented technology

This invention permits the upstream transmission of short packets of information in a cable TV system, and blocking upstream noise at all other times, and does so without interfering with image quality of normal TV viewing. A remotely operable ingress noise blocking filter is placed at the terminating junction between a subscriber's coaxial drop cable and a corresponding feeder tap in a cable TV system. The ingress noise blocking filter contains a high pass filter to pass the normal TV band. This high pass filter is bypassed by a section containing low pass filters and a switch operated when receiving a control signal from a cable modem during those short durations the cable modem is authorized to transmit an upstream signal. Low pass filters isolate the switching elements so that switching transients cannot occur in the downstream TV band. The level of the amplitude of the downstream signal is unaffected whether the switching elements are open or closed. Further, the switching arrangement provides a relatively constant impedance, both when the switching element is on and off to provide a high return loss and avoid signal reflections and maintain signal quality. In a diagnostic mode, the location of each noise source is determined by correlating the energy measured at each a set of frequencies across the band at the headend during those periods when the cable modem is allowed to transmit versus the energy received during those periods when the same cable modem is not authorized to transmit.

A compensated driver for maintaining constant impedance during data transfer from an integrated circuit comprises an output portion having an output device to transfer data from the integrated circuit and a mimic circuit portion having a sample output device scaled to a fraction of the output device adapted to accept a reference current and generate a sample voltage. A mimic circuit portion has a sample output device scaled to a fraction of the output device adapted to accept a reference current and generate a sample voltage. A differential amplifier portion is adapted to generate a control voltage in response to a reference voltage and the sample voltage. A predrive portion applies either a ground or the predetermined control voltage from the differential amplifier portion to the output stage portion in response to an input, the control voltage regulating the output device in the output stage portion to achieve a more constant impedance.

A Transmission Line Pulse (“TLP”) measurement system for testing devices such as integrated circuits (“ICs”), and especially for testing the electrostatic discharge (“ESD”) protection structures connected to terminals on such ICs. The TLP measurement system measures the pulsed voltage and / or current of a device under test (“DUT”) by recording voltage and / or current pulse waveforms traveling in a constant impedance cable to and from the DUT. The pulses going to and returning from the DUT are processed to create signal replicas of the voltage and current pulses that actually occurred at the DUT. Oscilloscope operating settings optimize the recording of these signal replicas by improving the measurement signal-to-noise ratio. This improved TLP system is especially useful when very short width pulses on the order of less than 10 nanoseconds are used to test the DUT's response.

An RF power amplifier having reduced memory effects is disclosed. This is achieved by a novel design of the DC supply feed network to achieve low impedance across video frequencies, whilst maintaining the correct RF output matching. One or more transmission zeros are provided in the bias circuit transfer function, which are positioned in the video bandwidth so as to provide low and relatively constant impedance across the video bandwidth. Also, a parallel DC feed line may be employed to reduce impedance across the video bandwidth. The reduction in memory effects allows improved performance of predistortion linearization techniques and an implementation in a feed forward amplifier employing predistortion linearization is also disclosed.

An input stage for an integrated circuit device provides constant gain in selectable modes of either differential or single-ended operation. In one embodiment, transconductance devices are arranged so that the input impedance of the input stage matches the signal source impedance, regardless whether the input stage is selected to operate in a differential mode or in a single-ended mode. In accordance with an alternative embodiment, constant-gain and constant-impedance conditions are maintained in a configuration that comprises and input signal attenuator. In one application, the input stage may serve as a low-noise amplifier (LNA) for an integrated transceiver.

The device for simulating a rectified constant impedance load provide by the present invention is to test a power product and comprises an analog-digital converter, a digital signal processor, a digital-analog converter, and an active electrical load module in order to replacing the passive components of a traditional rectified passive load. method for simulating a rectified constant impedance load being applied to test a power product and comprising the steps of: (S1) replacing the plurality of passive components of the rectified constant impedance load with a digital control module and an active electrical load module; (S2) establishing a passive load model function in order to represent the application relationships of the plurality of the passive components; (S3) executing the operation of the passive load model function by the digital control module in order to gain a load current value, and transferring the load current value to an analog control signal via the digital control module; and (S4) controlling the active electrical load module via the analog control signal so as to draw currents from the power product.