Amplifier circuit and output drive circuit thereof

Abstract

The invention provides an amplifier circuit and an output drive circuit thereof. The output drive circuit is used for receiving and driving a first input signal and a second input signal and comprisesan output circuit, a protection circuit and a bias control circuit. The output circuit is used for generating an output voltage at the signal output end according to the first input signal and the second input signal. The protection circuit is coupled to the output circuit and used for adjusting the voltage across two terminals of at least one electronic component of the output circuit accordingto the first bias voltage and the second bias voltage, so that the voltage across the two terminals is smaller than a predetermined voltage value. The bias control circuit is coupled to the signal output terminal, and is used for detecting the voltage level of the output voltage and dynamically adjusting the first bias voltage and the second bias voltage according to the voltage level of the output voltage.

Description

technical field [0001] The present invention relates to an amplifier circuit and its output driving circuit, in particular to an amplifier circuit suitable for various circuits with small load resistance, large output signal swing and driving large current. Background technique [0002] Generally speaking, a communication system (eg, a digital television system, a mobile communication system, etc.) transmits a signal to a receiving device through a communication medium. In many communication systems, the receiving device is often located far from the transmitting device, in which case signal loss can occur. Therefore, communication systems generally use amplifiers in transmitting and / or receiving devices to increase the voltage level of signals. [0003] figure 1 A circuit diagram of an amplifier is shown. The amplifier circuit 100 is an operational amplifier receiving a predetermined voltage VCM and an input voltage Vin for generating an output voltage Vout according to ...

AI Technical Summary

Problems solved by technology

When the cross-voltage across the transistor M1 or M2 is higher than 1.8 volts, the transistor M1 or M2 will be easily damaged, and the life cycle of the transistor M1 and M2 will be shortened, thus resulting in a problem of reduced reliability of the amplifier circuit.

Moreover, when the load resistance R_load is small (for example, the load resistance R_load is 37.5 ohm) and the voltage swing of the output voltage is large, the output current Iout can be between 21.5 mA and 64 mA. In order to withstand such a large current, the transistor needs to have a larger size, which will occupy a larger circuit area, resulting in the problem of high production cost

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