69results about "Line impedence variation compensation" patented technology

A method and system provides for execution of calibration cycles from time to time during normal operation of the communication channel. A calibration cycle includes de-coupling the normal data source from the transmitter and supplying a calibration pattern in its place. The calibration pattern is received from the communication link using the receiver on the second component. A calibrated value of a parameter of the communication channel is determined in response to the received calibration pattern. The steps involved in calibration cycles can be reordered to account for utilization patterns of the communication channel. For bidirectional links, calibration cycles are executed which include the step of storing received calibration patterns on the second component, and retransmitting such calibration patterns back to the first component for use in adjusting parameters of the channel at first component.

Impedance adjusting transistors are once inactivated on every occasion of changing an impedance adjusting code. After restoring the potential to an initially set potential by once inactivating the impedance adjusting transistors, the state of the transistors is switched according to the impedance adjusting code. By starting the potential from the initially set potential at the time of switching the state of the transistors, no switching noise is generated. Since no switching noise is generated, a comparator always carries out stable comparison and judgment and thus there is obtained a calibration circuit that ensures stable outputs.

Systems and methods are described for transmitting a waveform having a controllable attenuation and propagation velocity. An exemplary method comprises: generating an exponential waveform, the exponential waveform (a) being characterized by the equation Vin=De−A<sub2>SD< / sub2>[x−v<sub2>SD< / sub2>t], where D is a magnitude, Vin is a voltage, t is time, ASD is an attenuation coefficient, and vSD is a propagation velocity; and (b) being truncated at a maximum value. An exemplary apparatus comprises: an exponential waveform generator; an input recorder coupled to an output of the exponential waveform generator; a transmission line under test coupled to the output of the exponential waveform generator; an output recorder coupled to the transmission line under test; an additional transmission line coupled to the transmission line under test; and a termination impedance coupled to the additional transmission line and to a ground.

A serial interface interacting with a transmission pad system circuitry wherein a differential impedance is reckoned across the system voltage source, includes a scheme for controlling transmitter rise-fall transitions (to selectively speed up or slow down transitions) without requiring additional timing controls or affecting reflection coefficient of the transmitter port. The scheme uses at least one pre-charged capacitor, e.g., PMOS capacitor, interacting with the transmitter pad and connected through resistances or otherwise across the differential impedance with a switch. A modified scheme uses first and second parallely connected PMOS capacitors connectable with the transmission pad by switches, which may be NMOS switches. The scheme may be used in a MIPI D-PHY compliant DSI transmitter operating at, for e.g. 800 Mbps, and low signal common-modes. The scheme controls signal transition times of high speed circuitry including transmitters and uses a DATA signal which is already available to the circuitry.

A system and method to correct or cancel MOS linear region impedance curvature employing an analog solution to trim out the MOS linear region impedance curvature while accommodating PVT spreads in values of internal or external precision resistors. The linear region curvature correction may be obtained by using two MOS transistors in the pad driver / buffer and operating the transistors so as to proportionately increase output impedance of one of them when the output impedance of the other decreases, and vice versa. A linear pad impedance may be maintained over a range of Vpad values, while also maintaining the Vgs supplied to pad driver transistors at its maximum possible value to obtain greater linearity. The approach of the present disclosure relaxes the requirements on the voltage / current references used in the MOS pad drivers and makes tight impedance control possible, especially in a situation where the MOS fabrication process (typically all currently used processes) does not have available an internal precision resistor with a reasonably well controlled value.

An automatic impedance-matching method for a radiofrequency reception chain, which includes an antenna, an amplifier and a configurable impedance-matching network, arranged between the antenna and an input of the amplifier. The method includes two steps: acquiring measurement of a gain of the reception chain and of a noise level at an output of the amplifier and tuning the impedance-matching network according to the measurements. A radiofrequency reception chain allowing the method to be implemented is also provided.

The present invention relates to an automatic gain control apparatus and method in a wireless telecommunication system which measures the strength of received signals using preamble symbols and automatically control the gain of an amplifier based on the measurement results. The automatic gain control apparatus and method according to present invention performs automatic gain control of measuring sample power in a sample unit for input signals, acquiring a sample power average value during a unit symbol period, detecting a maximum value during one frame period for the acquired sample power average value and then calculating a gain control value based on it.

The present invention discloses a receiver capable of enhancing accuracy of signal reception. The receiver includes a variable termination resistance unit, coupled to at least one channel, for utilizing at least one termination resistance corresponding to the at least one channel to perform impedance matching, and a signal detection and termination resistance adjustment unit, for detecting at least one external calibration signal corresponding to the at least one channel from at least one external signal generator, and adjusting the at least one termination resistance.

The invention provides a transmission apparatus (100) for transmission of electrical signals between a line driver (205), which is connected to a transmission line (201), and a switching center (301), having an analog feedback device (101) for coarse setting of a line voltage level (210) on the transmission line (201), and a digital feedback device (102), which is coupled to the analog feedback device (101) and has a feedback filter device (118), designed such that a filter input signal (404) can be converted to a filter output signal (405) at a rate which is lower than the sampling rate (fa) of an analog / digital converter (104).