Parallel chopper-type transformer coupling and isolation amplifier

Abstract

The invention discloses a parallel chopper-type transformer coupling and isolation amplifier, which comprises a parallel chopper-type modulation circuit, an isolation transformer and a parallel chopper-type demodulation circuit, which are connected in sequence. The grounding end of a chopper tube of the parallel chopper-type modulation circuit is connected in series with a differential modulation chopper circuit, which forms a differential structure with the parallel chopper-type modulation circuit; the grounding end of a chopper tube of the parallel chopper-type demodulation circuit is connected in series with a differential demodulation chopper circuit, which forms a differential structure with the parallel chopper-type demodulation circuit; and a differential amplification circuit is connected after the parallel chopper-type demodulation circuit. Compared with an existing transformer isolation amplifier, the transformer coupling and isolation amplifier has lower temperature drift and higher transmission bandwidth; and besides, efficiency and signal-to-noise ratio thereof are roughly doubled.

Description

technical field [0001] The invention relates to the field of isolation transformers, in particular to an AC / DC general isolation amplifier used for parallel chopper modulation and demodulation transformers. Background technique [0002] A transformer-coupled isolation amplifier consists of two parts, a power transformer and a signal isolation transformer. In addition to providing the power required by the isolation amplifier, the power transformer also provides the required chopping modulation and demodulation signal to control the N or P channel FET switch to complete modulation and demodulation. The main function of the signal isolation transformer is to transmit the signal after chopping modulation, and play the role of coupling and isolation. [0003] The schematic diagram of the existing transformer-coupled isolation amplifier is shown in figure 1 As shown, the square wave generated by the power supply / square wave oscillator is coupled by the transformer to control th...

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Problems solved by technology

To suppress transient spikes such as figure 2 As shown, the usual practice is to add an RC absorption circuit, but adding this circuit is equivalent to generating an offset current for the amplifier connected later, and it will also increase the response time of the circuit, and the amplitude-frequency characteristic will be affected. Deterioration, not good for testing AC signals

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