Fujitsu Corporation

Fujitsu Semiconductor Limited

Win Chaivipas

Atsushi Matsuda

Daisuke Yamazaki

Masazumi Marutani

A signal transmission system includes a transmitter configured to encode a transmission signal to generate 2N (N: integer larger than or equal to two) binary signals among which a number of 0s and a number of 1s are equal to each other, and to transmit the 2N binary signals, 2N signal lines configured to transmit the 2N binary signals, respectively, and a receiver configured to detect a bit pattern among a plurality of possible bit patterns of the 2N binary signals in response to a plurality of differential components between 2N received signals received through the 2N signal lines, and to decode the detected bit pattern.

Signal transmission system

An oscillator circuit includes: a plurality of delay elements, a first delay element configured to receive a first oscillator signal outputted from a second delay element in one stage before the first delay element and a second oscillator signal outputted from a third delay element in two or more stages before the first delay element, the plurality of delay terminals being connected in a ring by at least three or more delay elements, and the first oscillator signal and the second oscillator signal having phases different from one another; and a bias voltage generator configured to change a ratio of a first input bias current for the first oscillator signal to a second input bias current for the second oscillator signal, in accordance with a first bias voltage and a second bias voltage supplied to the plurality of delay elements.

Oscillator circuit

A phase control circuit includes: a phase interpolation circuit including a first transistor connected between a power source and an output terminal, and configured to output an output signal from the output terminal by combining input signals having different phases with each other based on a ratio of input bias currents; a bias circuit configured to control an ON-resistance of the first transistor by adjusting a gate voltage of the first transistor based on a total amount of the input bias currents, and to maintain an output common voltage of the phase interpolation circuit regardless of the total amount; and a current controller configured to control a through rate of the output signal with respect to the input signals by adjusting the total amount.

Phase control circuit and receiving device

A timing adjustment circuit includes a detection unit to generate a detection signal in response to a first clock having a duty cycle of 50% and a first frequency, a second clock having a duty cycle of 50% and a second frequency that is half the first frequency, and a third clock having a duty cycle of 50%, the second frequency, and a phase displacement of 90 degrees relative to the second clock, the detection signal indicating timing relationship between the first clock and the second and third clocks, a low-pass filter to receive the detection signal, and a variable-delay circuit to adjust relative timing relationship between the first clock and the second clock in response to an output of the low-pass filter such that a center point of a pulse of the first clock is aligned with a center point of a pulse of the second clock.

Timing adjustment circuit, clock generation circuit, and method for timing adjustment

A receiver circuit includes: a data interpolation switched capacitor circuit which samples a data signal and outputs a voltage value interpolated from a sampled voltage value in correspondence with an interpolation code indicating an interpolation ratio; a comparator which performs comparison between the voltage value outputted from the data interpolation switched capacitor circuit and a threshold value; a phase detection circuit which detects a boundary based on an output of the comparator and decides whether to advance or delay a phase; and an interpolation code generation circuit which generates an interpolation code corresponding to an output of the phase detection circuit, wherein a phase offset related to sampling is imparted and an offset corresponding to an amount of the phase offset is imparted to the threshold value of the comparator.

Receiver circuit and method for controlling receiver circuit

A digitally controlled oscillator has a high-order &#x394;&#x3a3; modulator configured to be of at least an order higher than a first order and configured to input a digital control signal and output a pseudorandom digital output signal, a first-order &#x394;&#x3a3; modulator configured to input the pseudorandom digital output signal and generate a control pulse signal including a pulse width corresponding to the pseudorandom digital output signal, a low pass filter configured to pass a low frequency component of the control pulse signal, and an oscillator configured to generate a high-frequency output signal whose frequency is controlled based on the control pulse signal outputted by the low pass filter so as to be a frequency corresponding to the digital control signal.

Digitally controlled oscillator and digital PLL including the same

A first switching unit configured to switch a first state for inputting a first clock signal input from a first input terminal, and a second state for inputting an output signal of a second delay element, to a first delay element. A second switching unit configured to switch a first state for inputting a second clock signal input from a second input terminal, and a second state for inputting an output signal of a first delay element, to a second delay element. After the two clock signals are respectively taken in the first delay elements and the second delay elements by putting the first and second switching units into the first state, the control unit puts the first and second switching units into the second state. An output unit outputs a phase difference obtained by decoding values stored in FFs in the second state.

Time-to-digital converter and control method

A clock generating circuit includes: a counter that counts a number of pulses of an oscillation clock signal existed within one cycle of a reference clock signal; a first time-to-digital converter that generates a plurality of phases of first clock signals by delaying the oscillation clock signal; a second time-to-digital converter that generates a plurality of phases of second clock signals by delaying the oscillation clock signal by a short delay time; a third time-to-digital converter that generates a plurality of phases of third clock signals by delaying the delayed first clock signal; a delay control unit that outputs a delay control signal based on a difference between a cycle of the oscillation clock signal and a target cycle; and an oscillator that generates, based on a cycle of the reference clock signal, the oscillation clock signal whose cycle is 1/m of the cycle of the reference clock signal.

Clock generating circuit

A clock generator includes a delay circuit to have 2N delays, in which a delay time from a first delay of the 2N delays to a last delay is set to a length of one cycle of an input; a first phase-detector to detect a first phase-difference between the input and an output from the last delay; a first charge-pump to generate a first current according to the first phase-difference; a first loop-filter to adjust a delay amount of each of the 2N delays, based on a voltage of the first current; a second phase-detector to detect a second phase-difference between the input and an output from an Nth delay; a second charge-pump to generate a second current according to the second phase-difference; and a second loop-filter to adjust a duty ratio of an output from each of the 2N delays, based on a voltage of the second current.

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Kawasaki, Japan

Win Chaivipas