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提出了一种采用桥接T型带通滤波器(下面简称为BPF)补偿晶体管增益的匹配型放大器的新方案,报告了设计方法及试验结果。这种匹配型放大器除用在宽频带放大器中表现出阻抗性能良好以外,特别是在多级级联使用时还具有能控制由信号源或负载阻抗变化引起幅频特性变化足够小的优点。这就是说增益补偿电路所采用的桥接T型BPF的特性几乎不随信号源或负载阻抗的变化而变化,因而具有良好的阻抗特性。而且这种结构能广泛适用于具有—6分贝/每倍频程的大部分晶体管。为适用于1.7千兆赫中频放大器,试制指标规定为:带宽400兆赫,增益大于50分贝。结果是四个两级晶体管组成的增益约14分贝的单元放大器串联起来的总增益与各单元放大器增益的简单分贝之和的差在所需带内小于1分贝。大信号输入时的调幅-调相转换增益压缩1分贝时相位变化量小于8°。
A new scheme of matching amplifier which compensates the gain of transistor by using bridge T-band band-pass filter (BPF for short) is presented. The design method and test results are reported. In addition to being suitable for impedance matching in broadband amplifiers, this matched amplifier has the advantage of being able to control small enough variations in amplitude-frequency characteristics due to changes in signal source or load impedance, especially when used in cascaded cascades. This means that the characteristics of the bridging T-BPF adopted by the gain compensation circuit hardly change with the change of the signal source or the load impedance, and thus have good impedance characteristics. And this structure can be widely applied to most transistors with -6 dB / octave. For the 1.7 gigahertz IF amplifier, pilot specifications provided for: bandwidth 400 MHz, gain greater than 50 dB. The result is that the difference between the sum of the series gain of unit amplifiers of about four decibels in gain of about four decibels and the simple decibels of each unit amplifier gain is less than one decibel in the desired band. Amplitude Modulation at Large Signal Input - Phase Change Conversion Gain Less than 8 ° phase change when compressing 1 dB.