Abstract: An operational comparator 10 includes a current source circuit, load circuits driven by the current source circuit, and a current mirror circuit. The load circuits are constituted with MOS transistors, predetermined reference voltage is supplied to the gate terminals of MOS transistors, and each of signal voltages constituting the differential output signal of the differential output circuit is supplied to gate of MOS transistors.

Abstract: A signal receiver includes a first-stage circuit, a second-stage circuit, a current compensation circuit, and a biasing circuit. A first input end of the first-stage circuit receives a reference voltage, and a second end of the first-stage circuit receives an input signal. A first input end and a second input end of the second-stage circuit are respectively coupled to a first output end and a second output end of the first-stage circuit. The current compensation circuit is coupled to the first input end of the second-stage circuit for dynamically providing a compensation current to the first input end of the second-stage circuit in response to a biasing voltage, so as to stabilize its voltage level. The biasing circuit biases the first-stage circuit and the current compensation circuit and sets the biasing voltage of the current compensation circuit in response to the reference voltage.

Abstract: A switched capacitor has a differential amplifier and a sampling capacitance and a feedback capacitance at least one of which has a variable capacitance value, and is switchable between a first drive mode of amplifying an input signal with a positive gain responsive to the capacitance ratio of the sampling capacitance to the feedback capacitance and a second drive mode of amplifying the input signal with a negative gain responsive to the capacitance ratio. A control circuit changes the capacitance ratio, and also changes the drive mode of the switched capacitor, at predetermined timing.

Abstract: Disclosed are a high-efficiency power amplifier and base station device with respect to high-speed, broadband radio communication method. A broadband power supply circuit includes a linear voltage amplifier to which an input signal is applied, a resistor connected to an output side of the linear voltage amplifier, a switching regulator amplifying the voltage difference between both ends of the resistor to convert the amplified voltage difference into current, and a high frequency amplifier. The high frequency amplifier is designed to exhibit high efficiency at a frequency band where the efficiency of the switching regulator starts to be deteriorated, or at a high frequency band where the operation of the linear amplifier is dominant. In this case, the amplification of low frequency components are performed by the switching regulator, and the amplification of high frequency components are performed by the linear amplifier and the high frequency amplifier.

Abstract: A digitally controlled circuit is arranged to provide the combined functions of level shifting, multiplexing, and delay control functions. The circuit is compact, and uses lower power and lower overall noise susceptibility over other solutions. A programmable bias current is arranged to adjust the delay through the circuit. The bias current can be provided by a digitally controlled current source, a binary weighted current DAC, or other digitally controlled means. The multiplexing functions are provided by an input stage circuit that is current limited by the programmable bias current. An output stage is arranged to convert signals from the input stage to a desired voltage level.

Abstract: Methods and systems for reducing parasitic capacitance of a buffer for an electric circuit are disclosed and may include coupling a gate of a first transistor to a first differential input of the buffer via a first capacitor, coupling a gate of a second transistor to a second differential input of the buffer via a second capacitor. The first and second transistors may be biased by a common mode output of a direct current (DC) voltage source for the buffer. The common mode output of the DC voltage source may be directly coupled to at least one differential output of the buffer via an inductor. The first transistor and the second transistor may comprise NMOS transistors and/or PMOS transistors. The DC voltage source may comprise a PMOS transistor and/or an NMOS transistor.

Abstract: Aspects of a method and system for wide range amplitude detection are provided. In this regard, many electronic systems may require amplitude detection of a variety of signals with widely varying amplitudes. Aspects of the invention may comprise suitable logic, circuitry, and/or code to perform amplitude detection and may be easily configured to accommodate a wide range of amplitudes. In this regard, the configuration of the amplitude detector may be performed via simple design changes and/or may be dynamically configured by suitable logic, circuitry, and/or code. Accordingly, multiplexing a single instance of the wide range amplitude detector and/or multiplexing multiple instances of the wide range amplitude detector may result in reduced design time, reduced circuit size, and/or reduced cost.

Abstract: A low-current input buffer is disclosed. The buffer uses self-biased N and P channel differential pairs with their outputs tied together. The self-biasing assists in reducing current consumption. The combination of N and P-channel differential pairs results in symmetry across a wide range of reference and supply voltages.

Abstract: A signal conversion circuit 2 comprises a differential amplifier portion 10 and a source follower portion 20. When differential voltage signals INp and INn are input to a first input terminal 5 and second input terminal 6 respectively, operations occurs either in a mode in which only the differential amplifier portion 10 operates, or a mode in which both the differential amplifier portion 10 and the source follower portion 20 operate, or a mode in which only the source follower portion 20 operates, according to the levels of the differential voltage signals INp and INn. The differential amplifier portion 10 and source follower portion 20 have fewer components compared with a circuit comprising two differential amplifier circuits. By this means, the circuit area can be reduced, and in addition current consumption can be reduced. Also, because the source follower portion 20 performs non-inverting amplification of the differential voltage signals INp and INn, high-speed operation is possible.

Abstract: Protection against anti single event effects associated with strikes of energetic particles is provided in current-mode logic (CML) or similar integrated circuits (ICs) using a current-switching architecture.

Abstract: An input buffer receiver circuit for electronic devices (e.g., memory chips) to receive and process reduced-swing and high bandwidth inputs to obtain “buffered” output signals therefrom with symmetrical rising and falling delays, and without additional current dissipation over previous receiver circuits, is disclosed. The receiver circuit may include two stages of differential amplifier pairs (i.e., a total of 4 separated differential amplifiers). The differential amplifiers in the first stage convert the single-ended input signal to a full-differential signal, which is then converted back to a single-ended output signal by the differential amplifier pair in the second stage. The output of a P-diff first stage may be connected to the input of an N-diff second stage and the output of an N-diff first stage may be connected to the input of a P-diff second stage thereby creating a “cross” coupled structure.

Abstract: A single-ended differential sense amplifier comprises a dynamic reference voltage generation circuit and a differential sense amplifier circuit. Input data with an input data line voltage is provided to the differential sense amplifier circuit. The input data line voltage also feeds back to the dynamic reference voltage generation circuit, which then generates a dynamic reference voltage based on the input data line voltage. The differential sense amplifier circuit is coupled to the dynamic reference voltage generation circuit and receives the dynamic reference voltage for determining the input data. The dynamic reference voltage increases and the input data line voltage decreases when reading the input data of a logic state, e.g., logic “0.

Abstract: A bipolar differential output circuit includes an input differential bipolar stage for receiving an input signal and generating a differential output current. An output differential pair of bipolar transistors without a bipolar tail current source responds to the input signal by providing a representative output signal. And a current mirror circuit passes current from the input differential pair to the output differential pair.

Abstract: A gm compensation current source controls current that runs through a current source transistor, source-grounded transistors that determine a gain so that mutual conductance gm of the source-grounded transistors is compensated and the gain is compensated. A 1/r current source runs current inversely proportional to variation of load resistors of an amplifier so that gate bias points of gate-grounded transistors that are connected to the source-grounded transistors remain constant, and deterioration of linearity at a drain terminal of a gate-grounded transistor is suppressed.

Abstract: A circuit assembly for converting a differential input clock signal pair into a single-ended output clock signal comprises a NMOS differential amplifier (20) including two N-channel field-effect transistors (N1, N2) which converts the input clock signal pair (CLK, NCLK) applied to its differential inputs into a first single-ended signal, a PMOS differential amplifier (22) including two P-channel field-effect transistors (P3, P4) which converts the input clock signal pair applied to its differential inputs into a second single-ended signal, a bias circuit (N5, N6, N7, P5, P6) generating for each differential amplifier a bias voltage defining its working point at which said field-effect transistors (N1, N2; P3, P4) change state as a function of said input clock signal pair (CLK, NCLK), and a NAND circuit (32) for linking said first and said second single-ended signal and outputting the single-ended output clock signal (A-CLK) as the result thereof.

Abstract: A method for tuning a filter is provided. The method includes: enabling a VCO circuit, wherein at least a portion of the VCO circuit is selected from the filter; generating an oscillation signal by the VCO circuit according to a driving signal; comparing the oscillation signal with a reference signal and generating a comparison result; and adjusting the driving signal according to the comparison result.

Abstract: Methods and apparatus for properly biasing differential comparators are provided. Using a feedback relationship, a bias for a main stage that receives a first differential input of the comparator is produced. Separately, a feedback relationship produces a bias for a main stage that receives a second differential input. These biases, produced as a result of the feedback relationship between bias stages and stages that replicate the main stages, are applied to the main stages. The outputs of the differential comparator are differential outputs with improved common-mode rejection as a result of the feedback and replica biasing.

Abstract: An input buffer receiver circuit for electronic devices (e.g., memory chips) to receive and process reduced-swing and high bandwidth inputs to obtain “buffered” output signals therefrom with symmetrical rising and falling delays, and without additional current dissipation over previous receiver circuits, is disclosed. The receiver circuit may include two stages of differential amplifier pairs (i.e., a total of 4 separated differential amplifiers). The differential amplifiers in the first stage convert the single-ended input signal to a full-differential signal, which is then converted back to a single-ended output signal by the differential amplifier pair in the second stage. The output of a P-diff first stage may be connected to the input of an N-diff second stage and the output of an N-diff first stage may be connected to the input of a P-diff second stage thereby creating a “cross” coupled structure.

Abstract: A transconductor for receiving a differential voltage signal and outputting a differential current signal, includes two transconductors for receiving the differential voltage signal and outputting a single-end current signal. An inversion input terminal of one of the two transconductors is connected with a non-inversion input terminal of the other. The transconductor outputs a current signal output from each of the two transconductors as the differential current signal.

Abstract: A low voltage differential signal driver includes first and second current sources, a first branch and a second branch. The first branch includes at least two transistors and at least two resistors between them that are all connected in series between the first and second current sources, to define a first node between adjacent resistors that is configured to transmit and receive differential signals. The second branch also includes at least two transistors and at least two resistors between them that also are all connected in series between the first and second current sources, to define a second node between adjacent resistors that is also configured to transmit and receive differential signals.

Abstract: An electrical circuit for conversion from differential to single-ended includes a differential amplifier stage and first and second buffer circuits. The differential amplifier stage includes a first and a second input; and a first and a different second charging circuit that can be operatively coupled, respectively, with an output of the conversion circuit and with an auxiliary output. Each of the first and second buffer circuits is functionally arranged between one of said outputs and between one of said charging circuits. The buffer circuits being configured so as to substantially equalize relative impedances seen towards said outputs.

Abstract: Apparatuses, circuits, and methods to amplify signals with reduced jitter are disclosed. Embodiments generally comprise amplifiers coupled with apparatuses that adjust peak frequencies of the amplifiers to reduce jitter. In many system and apparatus embodiments, the frequency gain boosters receive one or more feedback signals derived from input signals applied to the amplifiers. The frequency gain boosters generally respond to the feedback signals by manipulating or controlling active loads coupled to the amplifiers. In controlling the active loads, the frequency gain boosters generally cause the active loads to peak at frequencies at or near the input signals, the result being attenuated jitter in an output signal of the amplifier.

Abstract: An apparatus for regulating voltage for at least one differential transistor pair having a voltage follower buffer, the voltage follower section having a first voltage-temperature response, includes: (a) a differential amplifier having two input loci and an output locus, a first input locus of the two input loci receiving a reference voltage; (b) a temperature responsive unit coupled between the output locus and ground; and (c) a feedback line coupled between the temperature responsive unit and a second input locus of the two input loci. The temperature responsive unit has a second voltage-temperature response similar to the first voltage-temperature response.

Abstract: A differential amplifier is disclosed. The differential amplifier includes a first load element coupled between a first voltage and a first node. A second load element is coupled between the first voltage and a second node. A current source is coupled between a second voltage and a third node. A first input element is coupled between the first node and the third node and receives an input signal so as to adjust a voltage level of the first node. A second input element is coupled between the second node and the third node and receives a reference voltage signal so as to adjust a voltage level of the second node. A third input element is coupled between the second node and the third node and receives the input signal so as to adjust the voltage level of the second node.

Abstract: Provided is a voltage level shift circuit including: a first voltage level shift circuit formed of a P-channel enhancement type transistor (M1) and an N-channel depletion type MOS transistor (M3); and a second voltage level shift circuit formed of a P-channel enhancement type transistor (M2) and an N-channel depletion type MOS transistor (M4). In the voltage lever shift circuit, a cascode circuit using an N-channel depletion type transistor (M5) is serially connected to the first voltage level shift circuit, a cascode circuit using an N-channel depletion type transistor (M6) is serially connected to the second voltage level shift circuit, and a unit for complementarily controlling bias voltages of the respective cascode circuits. As a result, an output signal of the voltage level shift circuit connected to an input of a differential amplifier circuit, for expanding an input voltage range of a signal, is not affected by fluctuations in power supply voltage.

Abstract: Disclosed are a high-efficiency power amplifier and base station device with respect to high-speed, broadband radio communication method. A broadband power supply circuit includes a linear voltage amplifier to which an input signal is applied, a resistor connected to an output side of the linear voltage amplifier, a switching regulator amplifying the voltage difference between both ends of the resistor to convert the amplified voltage difference into current, and a high frequency amplifier. The high frequency amplifier is designed to exhibit high efficiency at a frequency band where the efficiency of the switching regulator starts to be deteriorated, or at a high frequency band where the operation of the linear amplifier is dominant. In this case, the amplification of low frequency components are performed by the switching regulator, and the amplification of high frequency components are performed by the linear amplifier and the high frequency amplifier.

Abstract: A method, circuit, and system are disclosed. In one embodiment, the method comprises receiving a differential clock signal from two clock signal lines into a first differential pair of transistors of a first size, receiving the differential clock signal from the two clock signal lines into a second differential pair of transistors of a size smaller than the first size, converting the differential clock signal into a single-ended clock signal, outputting the single-ended clock signal through an inverter, and synchronizing any differential clock phase error by controlling the transconductance between the first differential pair of transistors and the second differential pair of transistors.

Abstract: A rail-to-rail amplifier is provided. The rail-to-rail amplifier includes a p-type differential pair, an n-type differential pair, switches, and an output stage. The switches are arranged to selectively couple either the p-type differential pair or the n-type differential pair to the output stage so that only one of the differential pairs is coupled to the output stage at a time.

Abstract: A voltage comparator contains low voltage devices (e.g., bipolar or MOS transistors) and high voltage devices (e.g., DMOS transistors). The low voltage devices, which cannot sustain a voltage greater than a relatively small range of variation that is substantially less than the range of potential variation of the input voltage, are connected in a differential amplifier configuration to perform precision differential measurements on the input voltage. The high voltage devices are interconnected with the low voltage devices in a manner that enables operating levels of the low voltage devices to move up/down, or ‘slide’, with variations in the input voltage, so that the low voltage devices are effectively immune to high levels of the input voltage.

Abstract: A memory device having a differential buffer is disclosed. In some embodiments, the memory device includes a differential buffer having a differential pair that is configured to receive input signals and generate output signals. In one embodiment, the differential buffer of the memory device includes adjustment circuitry coupled to the differential pair to enable adjustment of the amount of current dissipated by the differential buffer. Other memory devices, differential buffers, and methods are also disclosed.

Abstract: A current-integrating amplifier is provided. The current-integrating amplifier comprises a pair of input voltage nodes having a voltage difference there between; A pair of current sources that generate a current that produces a voltage drop over a resistor that corresponds to an equivalent voltage difference between the pair of input voltage nodes; a pair of output voltage nodes; a pair of pMOSFETs connected to the pair of output voltage nodes; a first pair of nMOSFETs connected the pair of output voltage nodes, the pair of pMOSFETS, the pair of input voltage nodes, a resistor, and a second pair of nMOSFETS; a resistor connected to the pair of current sources; a second pair of nMOSFETs connected to the first and third pairs of nMOSFETs; and a third pair of nMOSFETs connected to the second pair of nMOSFETs and connected to a bias generator that provides a predetermined constant current.

Abstract: A conventional driver circuit has difficulty in controlling output voltages such as an output amplitude and a middle voltage in a CML circuit. Furthermore, in another conventional driver circuit, a high level of an output voltage in the CML circuit is dropped from a power supply voltage. To solve these problems, disclosed is a driver circuit including: an amplitude converter which converts the amplitude of a differential output signal and outputs a differential output signal; an amplitude setting unit which sets the amplitude of the differential output signal; and a common voltage setting unit which sets a center potential of the amplitude of the differential output signal.

Abstract: A duty cycle and phase placement sampling circuit that can be used for high accuracy sampling and correcting the duty cycle and placement of differential clock signals is provided. The duty cycle and phase placement sampling circuit includes dual differential input stages and re-timed precharge signals that allow for high accuracy sampling of common mode logic clock phases.

Abstract: A low-current input buffer is disclosed. The buffer uses self-biased N and P channel differential pairs with their outputs tied together. The self-biasing assists in reducing current consumption. The combination of N and P-channel differential pairs results in symmetry across a wide range of reference and supply voltages.

Abstract: A Universal Serial Bus transmitter comprising a USBTXP input and a USBTXM input for receiving respective data signals, and a USBP driver and a USBM driver for applying the respective data signals to USBP and USBM wires respectively. The transmitter comprises a transmit signal generator responsive to an asserting edge of a signal at one of the USBP and USBM inputs to define a leading edge of a transmit signal (USBTXIP) and to a corresponding de-asserting edge of a signal at the other of the USBP and USBM inputs to define the subsequent trailing edge of said transmit signal (USBTXIP). Even if the duty cycles of the input signals USBTXP and USBTXM are substantially different from 50%, this does not cause unacceptable jitter of successive crossover points nor cause the crossover point voltage level to be outside the USB tolerance, centred on 50% of the voltage swings of the USBP and USBM signals.

Abstract: The invention relates to a comparator with a constant duty cycle for high frequency data signals. Such comparators are often part of an integrated circuit and particularly useful in the mobile phone technology. To achieve the desired constant duty cycle for high frequency data signals, the comparator according to the invention comprises a differential amplifier (M1, M2) having differential inputs (IN 1, IN2) forming the comparator inputs and a first and second amplifier output (Vo, Vo?) forming the comparator outputs of a first comparator stage. Further, a first differential current amplifier (A11) is provided and connected with its inputs to the amplifier outputs (Vo, Vo?) and with its output to the first amplifier output (Vo). Finally, a second differential current amplifier (A12) is connected with its inputs to the amplifier outputs (Vo, Vo?) and with its output to the second amplifier output (Vo?).

Abstract: An integrated circuit radio transceiver and method therefor includes a linear regulator an output transistor for producing a current into an output node of the regulator wherein an amplification block is operable to produce a bias signal to a gate terminal of the output transistor to operably bias the output transistor to produce the current into the output node of the regulator. A current steering amplification block is operably disposed to steer current in/out of the gate of the output transistor (depending on device type) based upon the current being conducted through the output node of the regulator exceeding a specified threshold. The current steering amplification block further includes a current sinking element operably disposed to sink a specified amount of current to define the specified threshold.

Abstract: Methods and apparatuses for detecting digital signals in high speed signaling systems. In at least one embodiment, at least one received input signal is combined with a plurality of predetermined reference signals according to a plurality of prior digital signal output states to generate a signal for detecting a present digital signal output state. In one aspect of the invention, a method for determining a digital signal state in a differential signaling system includes: comparing a first differential input signal to a second differential input signal; determining a prior digital signal output state; comparing the first differential input signal to one of a first reference voltage and a second reference voltage; comparing the second differential input signal to one of the first reference voltage and the second reference voltage; and determining a present digital signal output state from the prior digital signal output state and from all of the comparisons.

Abstract: An apparatus, device, and method for high-speed serial communications are provided. An input circuit is operable to receive an input signal, where the input circuit includes transistors forming (i) a first differential pair associated with a first current source and (ii) a second differential pair associated with a second current source. An output circuit is coupled to the input circuit and is operable to generate an output signal based on the input signal. A sensing circuit is operable to estimate a voltage associated with one of the current sources. A comparator is operable to compare the estimated voltage and a reference voltage and to selectively enable one of the differential pairs and disable another of the differential pairs based on the comparison. The differential pairs could be enabled and disabled using a first switch associated with the first differential pair and a second switch associated with the second differential pair.

Abstract: A low-current input buffer is disclosed. The buffer uses self-biased N and P channel differential pairs with their outputs tied together. The self-biasing assists in reducing current consumption. The combination of N and P-channel differential pairs results in symmetry across a wide range of reference and supply voltages.

Abstract: An output buffer circuit includes: a differential circuit; and first and second load circuits coupled between the differential circuit and a high power supply voltage VDDH. Such a differential circuit includes first and second NMOS transistors having low-voltage gate dielectric layers susceptible to deterioration at operation above a maximum gate-body voltage VgbMAX (where VDDH>VgbMAX), respectively. Body electrodes & source electrodes are coupled to a common node. Gate electrodes are coupled to first and second differential input signals, respectively, such that voltages on drains of the first and second NMOS transistors represent results of a differential switching operation, respectively. More particularly, the drains of the first and second NMOS transistors are coupled to the first and second loads. The common node is coupled to a bias voltage such that Vgb of the first & second NMOS transistors is VgbMAX?Vgb.

Abstract: In an operational amplifier including first and second power supply terminals, first and second input terminals, and a first and second output terminals, a first differential amplifier circuit includes first and second MOS transistors with a common source connected to a first tail current source, first and second load resistors and a first non-doped MOS transistor connected between the first and second resistors and the second power supply terminal. A second differential amplifier circuit includes third and fourth MOS transistors with a common source connected to a second tail current source, third and fourth load resistors and a second non-doped MOS transistor connected between the third and fourth load resistors and the second power supply terminal.

Abstract: The invention relates to a pulse shaping circuit for shaping electrical pulses driving an optical transmitter, e.g. a lased diode or an LED, and for providing electrical pulses having independently height and width-adjustable peaking at the edges thereof. The pulse shaping circuit of the present invention includes a high-pass RC filter with a differential output for providing transient electrical pulses from an input differential pulse, an adjustable voltage offset generating circuit, a differential amplifier for adjusting the width of the transient electrical pulses in dependence on the adjustable voltage offset, and a variable-gain current-steering amplifier for producing transient pulses with independently adjustable width and height.

Abstract: A transmission circuit includes a first-stage circuit, a second-stage circuit, a negative active feedback circuit and a current buffer. The first-stage circuit includes at least an active MOS device for receiving an input voltage and issuing a first voltage signal. The active MOS device has an inductive feature during operation in a high frequency mode to compensate the first voltage signal. In response to the first voltage signal, the second-stage circuit outputs a first output voltage. The negative active feedback circuit may enhance the bandwidth of the first output voltage. The current buffer may enhance the gain value of the first output voltage. A second voltage signal is issued from the first-stage circuit and compensated by the first output voltage transmitted from the current buffer to enhance the bandwidth and the gain value thereof. In response to the compensated second voltage signal, the second-stage circuit outputs a second output voltage.

Abstract: A method for tuning a filter is provided. The method includes: enabling a VCO circuit, wherein at least a portion of the VCO circuit is selected from the filter; generating an oscillation signal by the VCO circuit according to a driving signal; comparing the oscillation signal with a reference signal and generating a comparison result; and adjusting the driving signal according to the comparison result.

Abstract: A circuit having an enhanced input signal range includes a differential amplifier operative to receive at least first and second signals and to generate a difference signal at an output thereof which is a function of the difference between the first and second signals. The differential amplifier includes an input stage having at least first and second transistors having a first threshold voltage associated therewith and being operative to receive the first and second signals, respectively, and a load including at least third and fourth transistors having a second threshold voltage associated therewith, the first threshold voltage being greater than the second threshold voltage. The circuit further includes an output stage coupled to the differential amplifier and operative to receive the difference signal and to generate an output signal of the circuit that is indicative of the difference signal and is referenced to the supply voltage of the circuit.

Abstract: An adaptive hysteresis receiver processes a high speed digital signal. A differential receiver circuit compares the high speed digital signal to a reference voltage to generate an output signal. A register circuit latches the output signal, according to a clock signal, to produce a control signal. A reference voltage generator generates the reference voltage, from a plurality of voltages defining a deep hysteresis level and a shallow hysteresis level, in response to the output signal and the control signal.

Abstract: An output buffer circuit includes an input stage of which one end receives an input voltage and the other end receives an output voltage; a class AB output stage that increases a current flowing in the output stage when the difference between the input and output voltages is larger than 0; a floating current source that biases the class AB output stage; a summing circuit that is connected to the input stage, the floating current source, and the class AB output stage so as to sum up the current supplied from the input stage and the internal current supplied from the floating current source; and an offset compensating circuit that is connected to the input stage and is composed of a plurality of switching elements and resistors so as to detect an offset voltage to compensate.

Abstract: A differential receiver circuit receives a differential input signal including first and second input signals (DP, DM) and generates a single-ended output signal. The receiver circuit includes first and second comparators that receive the differential input signal and generate respective first and second differential output signals. A current summer is connected to the first and second comparators and receives the first and second differential output signals and generates a third differential output signal. A differential to single-ended converter is connected to the current summer and receives the third differential output signal and generates the single-ended output signal. The differential input signal varies from a ground voltage level to an external reference voltage level (VUSB), while the first and second comparators are made with devices that operate at an internal reference voltage level that is lower than the external reference voltage level.

Abstract: Disclosed is an output buffer circuit including a first differential transistor pair for differentially receiving a data signal from a differential input pair; and a second differential transistor pair for differentially receiving an emphasis data signal from another differential input pair; a pair of output resistor circuits via which the drains of first and second differential transistor pairs are connected to a power supply, said output resistor circuits each including a transistor; and a logic circuit adapted for receiving the data signal and the emphasis signal and for supplying a control signal which is of first and second values at the time of preemphasis and at other times to the transistors of the output resistor circuit, wherein the output resistance is relatively made larger at the time of emphasis, while being relatively smaller at the time of deemphasis.