通信电子线路第一章.ppt

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * School of Communication and Information Engineering n 1 2 3 4 5 6 1.00 0.64 0.51 0.43 0.39 0.35 K0.1 9.95 4.80 3.76 3.40 3.20 3.10 可见，当n 增大时，矩形系数 K0.1减小, 选择性得到了改善。 School of Communication and Information Engineering §1.5 放大器稳定性问题： School of Communication and Information Engineering 提高稳定性的措施 School of Communication and Information Engineering 采用共射——共基放大回路减小内反馈的影响的效果较好 School of Communication and Information Engineering 双栅极MOSFET RF放大器 School of Communication and Information Engineering 例3 School of Communication and Information Engineering School of Communication and Information Engineering 解 School of Communication and Information Engineering School of Communication and Information Engineering School of Communication and Information Engineering §1.6 小信号集中选频放大器 窄带 选频回路，如LC谐振回路 宽带 电阻和高频变压器等宽带负载 分立 调谐回路为主 集成 宽带负载集中选频放大器 高频小信号放大器分类 按频带分 按使用有源器件分 School of Communication and Information Engineering 1. 集中选频滤波器 压电陶瓷谐振器 声表面波滤波器 声表面波带通滤波器指标 中心频率MHz 10~1500 相对带宽 50%以上 最小带宽kHz 100 矩形系数 1.15 带外抑制dB 60以上 带内波动dB ±0.05 插入损耗 最大达25dB School of Communication and Information Engineering 2. 多级宽带放大器 集成电路MC1350 School of Communication and Information Engineering 集成放大器MC1350是用作RF/IF放大器的典型器件 MC1350放大器主要参数 功率增益 50dB AGC范围 +5V~+9V 带宽 58MHz和48MHz时 BW=4.5MHz 10.7MHz时BW=350kHz 455kHz时BW=20kHz 噪声系数 ≤8 dB 电源电压 18V消耗功率 625mW 1-3.exe School of Communication and Information Engineering School of Communication and Information Engineering 3 集成中频（IF）放大器 MC3359集成电路内部中频限幅放大级电路 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * School of Communication and Information Engineering School of Communication and Information Engineering 例1 一并联LC电路，已知电感为0.3mH，绕线阻抗2W，电容为0.47mF。试求： (1)f0；(2)Q；(3)Rp；(4)BW。 School of Communication and Information Engineering 解答： Scho