Abstract: There is provided a method and apparatus for performing an eye scan. Said apparatus comprises: a receiver for receiving input signals; an equaliser for processing said input signals; a data sampler for sampling said processed input signals at certain sampling points to produce a data output, said data sampler being controlled by a clock signal; an edge sampler for detecting the edges of the processed input signal; an early/late voter for deciding whether a current sampling point needs to be advanced or retarded. The early/late voter passes an Up/Down signal to an interpolator for maintaining said clock signal, said interpolator acting on said Up/Down signal to adjust the clock signal by stepping it forward or backward according to control need, so that said sampling point can be advanced or retarded.

Abstract: A differential data transmission system that transmits encoded data symbols as differential signals. A signal for transmitting symbols on a set of at least three parallel channels, each channel having a first terminal, P1 to PN, and each channel having a second terminal connected to a common node Z. The signal comprising for each symbol an active signal on two of those channels and an inactive signal on the remaining channel or channels, the symbols being distinguishable by which two of the channels have the active signals.

Abstract: There is provided a clock phase interpolator comprising a pair of output nodes, at least three complementary clock signal inputs, an equal plurality of current sources, and an equal plurality of clock switching sections. Each clock switching section is connected to switch, under the control of a complementary clock signal on a respective one of the complementary clock signal inputs, the current provided by a respective one of the current sources between the two output nodes. The current sources are controllable to provide interpolation between signals on the complementary clock signal inputs. Also provided is a clock phase interpolator comprising a pair of output nodes, two complementary clock signal inputs, an equal plurality of current sources, an equal plurality of clock switching sections.

Abstract: There is provided a CML to CMOS converter comprising two current sources both connected between a first power supply, having a first potential, and a driving node, first and second push-pull drive stages each having a current path connected between a second power supply, having a second potential, and the driving node, and each having a control input for one half of a CML signal and an output node. Each of the two output nodes is connected to the control node of a respective one of the current sources, each current source being connected to decrease the current it supplies to the driving node if the potential of its respective output of the converter moves towards the potential of the first power supply.

Abstract: There is provided a Clock recovery apparatus comprising: an early/late voter for deciding whether a current sampling point needs to be advanced or retarded, wherein said early/late voter passes an Up/Down signal to an interpolator for maintaining a clock signal; a frequency accumulator and rate multiplier 30 for generating further signals which are summed with those of the Up/Down signal of the early/late voter to provide an improved control signal to the phase interpolator. The accumulator is responsive to frequency changes in the input signal, and said interpolator acts on said Up/Down signals to adjust the clock signal by stepping it forward or backward according to control need, so that said sampling point can be advanced or retarded.

Abstract: There is provided a receiver equalizer comprising, a first equalizer unit having a basic equalizer stage and a negative impedance cell connected to said basic equalizer stage. Preferably the negative impedance cell comprises a pair of back to back transistors, and connected thereto a parallel resistor capacitor RC network. The basic equalizer stage comprises: a pair of current sources; a pair of transistors arranged as a differential pair, each transistor connected to a different one of the current sources; and a degeneration impedance connected in between the two current sources, and the transistors, wherein the negative impedance cell is connected across the outputs of the pair of transistors.

Abstract: A differential data transmission system that transmits encoded data symbols as differential signals. A signal for transmitting symbols on a set of at least three parallel channels, each channel having a first terminal, P1 to PN, and each channel having a second terminal connected to a common node Z. The signal comprising for each symbol an active signal on two of those channels and an inactive signal on the remaining channel or channels, the symbols being distinguishable by which two of the channels have the active signals.

Abstract: Apparatus for generating an oscillating signal in a desired phase relationship with an input signal, including a mixer arranged to receive a pair of reference signals oscillating at a common frequency and having a phase offset between them, and to mix the reference signals in variable proportions according to the value of input weighting signals to generate an output signal. A comparator is to compare the phase of the output signal with that of the input signal to determine whether the signals are in the desired phase relationship and, if not, to output one or more control signals indicative of the required adjustment in the phase of the output signal to achieve the desired phase relationship. An adjustable ring oscillator including a plurality of stages is connected in a ring and arranged to propagate oscillations around the ring.

Abstract: Apparatus for generating an oscillating signal in a desired phase relationship with an input signal, including a mixer arranged to receive a pair of reference signals oscillating at a common frequency and having a phase offset between them, and to mix the reference signals in variable proportions according to the value of input weighting signals to generate an output signal. A comparator is to compare the phase of the output signal with that of the input signal to determine whether the signals are in the desired phase relationship and, if not, to output one or more control signals indicative of the required adjustment in the phase of the output signal to achieve the desired phase relationship. An adjustable ring oscillator including a plurality of stages is connected in a ring and arranged to propagate oscillations around the ring.

Abstract: A differential data transmission system that transmits encoded data symbols as differential signals. A signal for transmitting symbols on a set of at least three parallel channels, each channel having a first terminal, P1 to PN, and each channel having a second terminal connected to a common node Z. The signal comprising for each symbol an active signal on two of those channels and an inactive signal on the remaining channel or channels, the symbols being distinguishable by which two of the channels have the active signals.

Abstract: Parallel transmitted data in a plurality of channels is synchronised by generating a clock on the basis of the received data and synchronising the data received on each channel with the generated clock signal (50).