晶體三極管開(kāi)關(guān)混頻電路研究
2020年電子技術(shù)應(yīng)用第9期
張宏強(qiáng)，王 勇，劉乃安
西安電子科技大學(xué) 通信工程學(xué)院，陜西 西安710071
摘要： 針對(duì)傳統(tǒng)的乘法器混頻方式受本振信號(hào)影響，且存在很多干擾和失真，很大程度影響接收機(jī)的性能，采用晶體三極管開(kāi)關(guān)混頻方法解決這一問(wèn)題。詳細(xì)推導(dǎo)了開(kāi)關(guān)混頻的數(shù)學(xué)公式，通過(guò)對(duì)方波信號(hào)進(jìn)行傅里葉級(jí)數(shù)展開(kāi)，提出了I型、II型開(kāi)關(guān)混頻的數(shù)學(xué)模型，并針對(duì)NPN三極管開(kāi)關(guān)電路提出設(shè)計(jì)方案。在Multisim軟件環(huán)境中實(shí)施了仿真驗(yàn)證，以AM信號(hào)為例進(jìn)行三極管開(kāi)關(guān)混頻，引入加速電容消除了電路的負(fù)峰切削失真,并濾出中頻信號(hào)，仿真結(jié)果較為理想。理論和實(shí)踐表明，基于晶體三極管開(kāi)關(guān)的混頻方式避免了本振信號(hào)的干擾，可提高接收機(jī)性能。
中圖分類號(hào)： TN710.2
文獻(xiàn)標(biāo)識(shí)碼： A
DOI：10.16157/j.issn.0258-7998.200240
中文引用格式： 張宏強(qiáng)，王勇，劉乃安. 晶體三極管開(kāi)關(guān)混頻電路研究[J].電子技術(shù)應(yīng)用，2020，46(9)：127-131，136.
英文引用格式： Zhang Hongqiang，Wang Yong，Liu Naian. Research on BJT switch mixing circuit[J]. Application of Electronic Technique，2020，46(9)：127-131，136.
文獻(xiàn)標(biāo)識(shí)碼： A
DOI：10.16157/j.issn.0258-7998.200240
中文引用格式： 張宏強(qiáng)，王勇，劉乃安. 晶體三極管開(kāi)關(guān)混頻電路研究[J].電子技術(shù)應(yīng)用，2020，46(9)：127-131，136.
英文引用格式： Zhang Hongqiang，Wang Yong，Liu Naian. Research on BJT switch mixing circuit[J]. Application of Electronic Technique，2020，46(9)：127-131，136.
Research on BJT switch mixing circuit
Zhang Hongqiang，Wang Yong，Liu Naian
School of Telecommunications Engineering，Xidian University，Xi′an 710126，China
Abstract： In allusion to the problem that traditional multiplier mixing method is affected by local oscillator and there exists interferences and distortions, which greatly affects the performance of receiver, a bipolar junction transistor(BJT) switch mixing method is proposed. The mathematical formula of switch mixing is deduced in detail, and two mathematical models, I-type and II-type switch mixing models are proposed by using Fourier series expansion of square wave. Based on NPN BJT switch, a mixing circuit is designed, and simulation is carried out on Multisim software environment. AM signal is used as an example to mix on BJT switch. Acceleration capacitor is added to eliminate negative peak cutting distortion and intermediate frequency signal is filtered out. The results of simulation are ideal. It is proved theoretically and practically that BJT switch mixing method prevents the interference of local oscillator signal, which can enhance receiver performance.
Key words : bipolar junction transistor；mixing；local oscillator signal；Fourier series；acceleration capacitor
0 引言
混頻一般通過(guò)非線性元件或者專用的集成電路乘法器來(lái)實(shí)現(xiàn)，混頻信號(hào)的幅度和相位信息受本振信號(hào)影響，并且也會(huì)引入很多干擾和失真，這些都會(huì)降低接收機(jī)的性能[1]。開(kāi)關(guān)混頻方式可解決以上問(wèn)題，且晶體三極管廉價(jià)易得，開(kāi)關(guān)電路易于實(shí)現(xiàn)，原理如圖1所示。
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作者信息:
張宏強(qiáng)，王 勇，劉乃安
(西安電子科技大學(xué) 通信工程學(xué)院，陜西 西安710071)
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