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Differential output circuit

A differential output and differential current technology, which is applied in multiple input and output pulse circuits, logic circuit connection/interface layout, transmission system, etc., to achieve the effect of reducing the occupied area rate and reducing the cost

Inactive Publication Date: 2007-08-22
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In such cases, the conventional measures described above are necessary to adjust the output offset voltage to remain within the range determined by the standard, although these measures have some of the above-mentioned disadvantages
However, when the data transmission distance is relatively short, for example, when LVDS is implemented by a single substrate, it is not necessary to necessarily use a constant current circuit section, a feedback circuit, a replica circuit, or other similar circuits to suppress output skew voltage change

Method used

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Embodiment approach 1

[0029] FIG. 1 shows the configuration of a differential output circuit according to Embodiment 1 of the present invention. The differential output circuit of Embodiment 1 includes: a current source 11 that provides a constant current from a power supply to a receiving circuit (not shown) terminal resistor 100, and a current source 12 that introduces a constant current from the terminal resistor 100 to ground, placed in Output polarity switching circuit 13 between current source 11 and current source 12 , resistor 14 and voltage source 15 . One end of the resistor 14 is connected to a connection point between the current source 11 and the output polarity switching circuit 13 . The other end of the resistor 14 is connected to a voltage source 15 . The voltage source 15 provides a predetermined voltage, for example, about half of the power supply VDD.

[0030] In the differential output circuit of Embodiment 1, differential currents are generated by current sources 11 and 12 . ...

Embodiment approach 2

[0034] FIG. 2 shows the configuration of a differential output circuit according to Embodiment 2 of the present invention. The differential output circuit of Embodiment 2 includes: a current source 11 that provides a constant current from the power supply to the receiving circuit (not shown) terminal resistor 100, and a current source 12 that introduces a constant current from the terminal resistor 100 to the ground, placed in An output polarity switching circuit 13 between the current source 11 and the current source 12 , and a resistor 14 . The current value of the current source 11 is set to be greater than the current value I of the current source 12 by ΔI. For example, the current source 11 may be composed of a current source having the same current value as the current source 12 and a current source having a current value of ΔI connected in parallel. One end of the resistor 14 is connected to a connection point between the current source 11 and the output polarity switc...

Embodiment approach 3

[0039]FIG. 4 shows the configuration of a differential output circuit according to Embodiment 3 of the present invention. The differential output circuit of Embodiment 3 includes: a current source 11 that provides a constant current from a power supply to a receiving circuit (not shown) terminal resistor 100, and a current source 12 that introduces a constant current from the terminal resistor 100 to ground, placed in Output polarity switching circuit 13 between current source 11 and current source 12 , resistors 14 a and 14 b and voltage source 15 . One end of the resistor 14 a is connected to the output terminal 16 a of the differential current, and the other end of the resistor 14 a is connected to the voltage source 15 . One end of the resistor 14b is connected to the output terminal 16b of the differential current, and the other end of the resistor 14b is connected to the voltage source 15 . The voltage source 15 provides a predetermined voltage, for example, about half ...

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PUM

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Abstract

A differential output circuit which performs data transmission by means of a differential current comprises: a first current source for outputting an electric current to the outside of the circuit; a second current source for introducing an electric current from the outside of the circuit; an output polarity switching circuit for switching the polarity of the differential current generated by the first and second current sources; a voltage source for supplying a predetermined voltage; and a resistor connected between a predetermined node and the voltage source, the predetermined node being interposed between the first and second current sources.

Description

[0001] related application [0002] This application claims priority from Japanese Patent Application No. 2003-392214 filed on November 21, 2003, the entire contents of which are incorporated herein by reference. technical field [0003] The invention relates to an interface of a semiconductor device, in particular to a current-driven interface technology. Background technique [0004] Low voltage differential signaling (hereinafter referred to as "LVDS") has been widely used as a current driving interface. LVDS achieves signal transmission through the polarity of a small-amplitude voltage, which is generated on the termination resistor at the receiving end due to the differential current output from the transmitting end. LVDS uses differential signaling and therefore has high immunity to common-mode noise. However, if the DC offset voltage is exactly at the center of the differential signal amplitude, then it is not suitable for the supply voltage and ground, and the com...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03K19/0175H03K5/003H03K5/22H04L25/02
CPCH03K5/003H04L25/0274H04L25/028
Inventor 青池昌洋宫田美模朴井高宏
Owner PANASONIC CORP