Radio frequency power detection circuit

Abstract

The invention discloses a radio frequency power detection circuit including a first stage circuit, a second stage circuit and a protection circuit. The first stage circuit comprises an amplifier transistor for changing synchronously and proportionally along with the output of a power transistor in a radio frequency power amplifier. The second stage circuit comprises a diode one and a diode two for power detection of a radio frequency signal output by the first stage circuit. The diode one is used to set a bias point with a temperature compensation feature for the diode two. The protection circuit comprises a protection transistor for starting the protection transistor to reduce the output power of the radio frequency amplifier when the output power of the radio frequency amplifier exceeds a normal range. The radio frequency power detection circuit has a limit protection function, can output a voltage with a large varying range when the output power is small, can be disposed on an input end or an intermediate stage of the radio frequency amplifier, and is not sensitive to temperature changes.

Description

technical field [0001] The present application relates to a radio frequency power detection circuit, in particular to a radio frequency power detection circuit capable of limiting the output power of a radio frequency power amplifier when its output power exceeds a normal range. Background technique [0002] In the radio frequency transmitter, the radio frequency power amplifier is used to amplify the power of the modulated signal to meet the signal size transmitted by the antenna, and send it to the antenna for transmission. In the radio frequency receiver, the radio frequency power amplifier is used to amplify the power of the received signal to obtain a signal size that meets the requirements of the subsequent circuit, and send it to the subsequent circuit for processing. Usually, a special power detection circuit is required to detect the magnitude of the radio frequency signal output by the radio frequency power amplifier. [0003] Most of the existing radio frequency ...

AI Technical Summary

Problems solved by technology

However, the follower amplifier unit in this power detection circuit adopts a common collector transistor amplifier structure, and the output voltage swing is limited to a certain extent.

At the same time, when it is detected that the output power of the RF power amplifier is abnormal, it cannot provide protection measures for limiting the output power of the RF power amplifier

Images