A low resistance signal switching circuit

Abstract

The invention relates to a low-resistance signal switching circuit. The low-resistance signal switching circuit comprises a first voltage follower, a second voltage follower, a first photorelay, a second photorelay, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a first transistor, a first diode, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a third operational amplifier, a fourth operational amplifier, a fifth operational amplifier, a first power supply and a reference power supply. The low-resistance signal switching circuit can prevent mutual interference between other circuit devices in the low-resistance signal switching circuit and an external working circuit, and using an analog switch as a signal switching element is avoided, so that on-state resistance decreases substantially and reaches the milliohm level. Furthermore, the low-resistance signal switching circuit is high in signal switching speed in the working process and long in service life.

Description

technical field [0001] The invention relates to a signal switching circuit with low resistance. Background technique [0002] In circuit application, we often encounter the problem of switching between external signals and internal signals, that is, when there is an external signal input, the circuit automatically switches to the external signal; when the signal is removed, the circuit automatically returns to the internal signal input state. A typical technical case is the switch between built-in MIC and external MIC. [0003] There are currently several options for signal switching: [0004] 1. Switching is performed through a mechanical switching structure. For example, for a MIC socket, when an external MIC plug is inserted, the shrapnel in the socket is disconnected from the original contact point and connected to the inserted plug, thus completing the signal switching. [0005] 2. Manual switching, switch between internal and external signals through a single-pole d...

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Problems solved by technology

[0011] 3. The third solution solves the problem of digital control, but the size of the circuit increases, the switching speed is not very fast, and the contacts are also easy to oxidize

The minimum on-resistance of a typical analog switch CD4053 is about 80 ohms, and the on-resistance of a relatively high-end analog switch MAX4887 is also about 5 ohms. The on-resistance is relatively large, and the use on communication lines will seriously affect the communication distance.

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