Broadband active balun circuit

Abstract

The invention discloses a broadband active balun circuit, wherein the process for converting single-ended signals into double-ended balance signals comprises two stages. The first stage provides a completely-symmetrical circuit structure-based current multiplexing single-to-double circuit, wherein the current multiplexing single-to-double circuit comprises a source follower, a common-source amplifier and a static biasing circuit which is used for ensuring that the source follower and the common-source amplifier asymmetrically biases. For the second stage, a differential amplifier circuit is used for amplifying differential signals obtained from the preceding stage; the differential amplifier circuit is connected with the output end of the current multiplexing single-to-double circuit so as to satisfy the requirements of processing signals for following circuits and to play a certain corrective role for the mismatch of amplitude outputted by the preceding stage. The broadband active balun circuit disclosed by the invention can obtain output signals with equal amplitude and differential phase by using input voltage signals below 10GHz; and the amplitude deviation can be further improved by only using a one-stage amplifying circuit, thus the circuit scale is reduced.

Description

technical field [0001] The invention relates to a balun circuit, in particular to a broadband active balun circuit. Background technique [0002] In a radio frequency system, the receiver front end has been proven to be the most critical module. The transmitter usually sends a single-ended signal, and in order to improve the system's rejection of common-mode signals, thereby eliminating glitches and interference, and improving system reliability and stability, it is necessary to convert the received signal into a differential signal Follow up. In today's applications, a balun circuit is generally used to solve this conversion problem. [0003] For the existing common balun circuit, there are the following main problems: (1) The applicable bandwidth of the passive balun is too narrow; (2) The asymmetry of the differential output terminal of the active balun circuit itself causes the imbalance of the output signal amplitude and phase ; The imbalance of the output phase ampl...

AI Technical Summary

Problems solved by technology

[0003] For the existing common balun circuit, there are the following main problems: (1) The applicable bandwidth of the passive balun is too narrow; (2) The asymmetry of the differential output terminal of the active balun circuit itself causes the imbalance of the output signal amplitude and phase ; Pseudo-differential pair output phase amplitude imbalance at high frequency; (3) Some balun circuits use inductance, which is limited by the integration process and is not suitable for low-frequency applications

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