Signal amplification circuit and active bias circuit

Abstract

The embodiment of the invention provides a signal amplification circuit and an active bias circuit. The signal amplification circuit comprises the active bias circuit and a radio frequency amplification circuit; the active bias circuit comprises a first branch circuit and a second branch circuit connected with the first branch circuit in parallel; the second branch circuit comprises an operationalamplifier; and the active bias circuit outputs bias voltage through the operational amplifier; and the radio frequency amplification circuit is connected with the active bias circuit and is used foramplifying an input signal input into the signal amplification circuit under the action of the bias voltage. According to the invention, the dependence of the active bias circuit on the power supply voltage can be reduced, so that the starting voltage of the whole circuit is reduced; the starting work can be realized under lower power supply voltage; stable bias voltage is input into the radio frequency amplification circuit; and the amplification function of the radio frequency amplification circuit is realized.

Description

technical field [0001] This application relates to the field of circuits, involving but not limited to a signal amplification circuit and an active bias circuit. Background technique [0002] In the mobile communication system, after the radio frequency signal is input, it is amplified by the power amplifier and then output. Among them, if the amplifier composed of transistors can amplify the radio frequency signal without distortion, it must ensure that the emitter junction of the transistor is positively biased and the collector Junction reverse bias. Therefore, the signal amplifying circuit usually requires an additional bias circuit to provide appropriate voltage and current to ensure the normal amplification of the transistor. [0003] The signal amplifying circuit in the related art includes an active bias circuit and a radio frequency amplifying circuit, wherein, the active bias circuit includes two triodes connected in series and grounded and an emitter follower (Em...

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Problems solved by technology

[0004] However, since the active bias circuit in the related art has two triodes connected in series, the active bias circuit needs a higher power supply voltage (Vbat) to start the normal operation of the whole circuit, but this is not necessary for mobile terminals. is an obvious limiting factor

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