Low differential voltage output circuit

Abstract

A low differential voltage output circuit comprises a voltage generator and a differential output unit. The voltage generator comproses a first PMOS transistor, a first amplifier circuit, a unity gain stage, a first and s second NMOS transistors. The differential output unit comprises a first controlled current source, a second controlled current source, a common mode voltage circuit and a first, a second, a third and a fourth switches. The invention directly provides the common mode voltage to the differential output unit by the voltage generator, overcomes channel modulation effect of the MOS transistor and increases driving force of the common mode voltage, so the reactive time of the invention changes small, the output current of the differential output unit is in proportion with the reference current received by the voltage generator, and only one voltage generator can meanwhile connect with a plurality of differential output units in series.

Description

technical field [0001] The invention relates to an output circuit, in particular to a low differential voltage output circuit. Background technique [0002] In recent years, electronic products have developed more diversified. In order to enable communication between electronic products, integrated circuits, or functional modules in integrated circuits, so as to optimize the functions of each product, each A transmission interface also came into being. [0003] In order to reduce electromagnetic interference (EMI) and power consumption, most of these transmission interfaces are designed as differential outputs, such as figure 1 The differential output circuit in is shown. figure 1 It is a schematic diagram of an existing differential output circuit and its arrangement position. Please refer to figure 1 , the differential output circuit is set inside the chip, and the circuit includes a differential output unit composed of MOS (metal-oxide-semiconductor) transistors 102 -...

AI Technical Summary

Problems solved by technology

However, since the differential output unit must be controlled by the feedback circuit 130, the response time of this type of transmission interface is limited, and its optimal conditions will also drift due to process variations.

[0006] In addition, because a general chip contains multiple sets of differential output units, and each differential output unit needs to be equipped with a feedback circuit for feedback control, resulting in a substantial increase in cost

From the above disadvantages, it can also be imagined that when the system needs to transmit more differential signals, the circuit scale will become quite complex

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