Signal amplification circuit with time-varying gain

Abstract

The invention discloses a signal amplification circuit with a time-varying gain. A variable resistor is connected to an input link or a feedback link of an amplifier, the resistance of the variable resistor is controlled by the voltage of a charging and discharging capacitor, the variable resistor can be achieved by a field-effect transistor or other semi-conductor devices with features of the variable resistor, the field-effect transistor has a variable resistor region, equivalent resistances between the drain and the source of the field-effect transistor working in the variable resistor region are controlled by a gate-source voltage, the charging and discharging of the charging and discharging capacitor are controlled by external signals, and during charging or discharging, voltages at two ends of the capacitor increase or decrease over time, so that the resistance of the variable resistor controlled by the voltages varies accordingly. The variable resistor is connected to the input link or the feedback link of the amplifier, so that the gain of the amplifier increases or decreases over time. The signal amplification circuit is simple in structure, easy to implement and capable of meeting the requirement for the time-varying gain required by detection.

Description

technical field [0001] The invention relates to the technical field of electronic circuits, in particular to a variable gain amplifying circuit for amplifying input signals through variable gain. Background technique [0002] In some signal detection fields, the measured signal decays or increases rapidly with time. For example, the time difference method is used to measure the microwave signal and ultrasonic signal of the distance. The signal is sent out from the sensor and reflected back to the sensor by the surface of the medium. to calculate the measured distance. For a transmitted signal with a certain energy, the closer the measured distance is, the shorter the propagation time is, and the stronger the reflected signal is; the farther the distance is, the longer the propagation time is, the weaker the reflected signal is, and it decays exponentially. A signal amplification circuit with a fixed magnification cannot adapt to such signal changes. Amplifying circuits wi...

AI Technical Summary

Problems solved by technology

But the disadvantage is that the gain range of this circuit is small, and its operating frequency and conversion rate often cannot meet the needs of actual detection.

For example, the signal sent by the time difference method is usually a pulse modulation signal, which requires the amplifier to have a high signal conversion rate. The common digital programmable gain control amplifier is difficult to meet the needs in this index.

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