Passive broadband mixer

Abstract

The invention discloses a passive broadband mixer, comprising: a local oscillator balun, a radio frequency balun, a first diode D1, a second diode D2, a third diode D3, a fourth diode. D4, an inductive compensation unit and lossy inductive grounding network. The passive broadband mixer disclosed by the invention can realize a mixer with a bandwidth ratio of less than 1:7, and a point with deteriorative isolation is effectively suppressed without affecting the full-band variable frequency loss; and in the full-band of the design, the full-band index of a local oscillator radio frequency port isoptimized, and the application of the broadband mixer in a communication system can be well met.

Description

technical field [0001] The invention relates to the technical field of integrated circuits, in particular to a passive broadband mixer. Background technique [0002] Mixers have been widely used in communication and are the key components to realize frequency conversion. In the field of integrated circuits, passive mixers are preferred in many scenarios due to their advantages such as good port isolation, wide bandwidth, and no need for DC power supply. Because it requires a relatively large driving power of the local oscillator, the isolation index between the local oscillator port and the radio frequency port is particularly important in the application. Because if it leaks out through the radio frequency port, and then radiates back through the antenna, it will cause interference to other devices. Furthermore, the circuit may be received back from the antenna, causing problems such as self-mixing and signal blocking (sensitivity degradation), which seriously interferes ...

AI Technical Summary

Problems solved by technology

To achieve a double-balanced structure, you need to use a balun circuit. The commonly used balun is composed of two coupled microstrip lines whose electrical length is a quarter of a wavelength. It can achieve ultra-wide bandwidth in a 50-ohm matching environment. , but as a unidirectional conduction device, it is difficult to achieve broadband matching with the balun circuit, and the balun circuit is the key factor determining the isolation index between the local oscillator and the RF port

Therefore, we can see that the traditional broadband (generally the bandwidth ratio is greater than 4) passive double-balanced mixer, in the entire frequency band, there will be a section of the isolation index between the frequency bands is relatively poor, such as figure 2 shown

The worst point of the isolation index is -20dB, it is difficult to optimize the isolation index of the whole frequency band

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