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公开(公告)号：US4758793A
公开(公告)日：1988-07-19
申请号：US13100
申请日：1987-02-10
申请人： Marc R. Sheade , Paul A. Murphy
发明人： Marc R. Sheade , Paul A. Murphy
CPC分类号： H03G3/3036 , H04N5/148
摘要： A Detector Log Video Amplifier (DLVA) comprising a first RF detector for detecting the power levels of received RF signals having power levels within a first range (e.g., -40 dBm to -20 dBm) and producing corresponding first video frequency signals having amplitudes representative thereof, from which are produced output signals having amplitudes logarithmically proportional to such received signals. A second RF detector detects the power levels of received RF signals having power levels within a second range (e.g., -20 dBm to +20 dBm) and produces corresponding second video frequency signals having amplitudes representative thereof, from which are produced output signals having amplitudes logarithmically proportional to such received signals. A control signal is produced from the second video frequency signals, the control signal having a level in accordance with the power levels of received RF signals. Received RF signals having power levels equal to or exceeding a first level (e.g., 0 dBm) are attenuated in accordance with the control signal level and coupled to the first detector. A limiter is responsive to the power levels of received RF signals exceeding a second level (e.g., +5 dBm) for limiting the power levels of such RF signals coupled to the attenuator in accordance with the power levels of such signals exceeding the second level. With such arrangement, the RF signals coupled to the first detector are prevented from exceeding the first level, thereby significantly reducing the DLVA's recovery time, for example to less than 500 nanoseconds.
摘要翻译： 一种检测器对数视频放大器（DLVA），包括用于检测具有第一范围（例如，-40dBm至-20dBm）内的功率电平的接收RF信号的功率电平的第一RF检测器，并产生具有幅度代表性的对应的第一视频信号 产生具有与这种接收信号成对数成正比的幅度的输出信号。 第二RF检测器检测具有在第二范围（例如，-20dBm至+ 20dBm）内的功率电平的接收RF信号的功率电平，并且产生具有其代表幅度的相应的第二视频信号，产生具有振幅的输出信号 与这样的接收信号成对数比例。 从第二视频信号产生控制信号，控制信号具有与所接收的RF信号的功率电平相对应的电平。 具有等于或超过第一电平（例如，0dBm）的功率电平的接收RF信号根据控制信号电平衰减并耦合到第一检测器。 限制器响应超过第二电平（例如，+ 5dBm）的接收RF信号的功率电平，用于根据超过第二电平的这种信号的功率电平来限制耦合到衰减器的这种RF信号的功率电平。 通过这样的布置，防止耦合到第一检测器的RF信号超过第一级，从而显着降低DLVA的恢复时间，例如小于500纳秒。
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公开(公告)号：US5898913A
公开(公告)日：1999-04-27
申请号：US845749
申请日：1997-04-25
CPC分类号： H03D7/1441 , H03D7/1433 , H03D7/1458 , H03D7/1466 , H03D7/1483 , H03D2200/0017 , H03D2200/0043 , H03D7/125
摘要： A frequency converter employs a balanced bridge mixer of switching elements such as field-effect transistors (FETs) with a local oscillator supplying control signals to gate terminals of the transistors. A carrier at intermediate frequency (IF) or at radio frequency (RF) is modulated for communication of data, and is applied to alternate nodes of the bridge. The remaining bridge nodes supply output signals to respective branches of an output circuit. Each branch of the output circuit is provided with a bandpass filter having a spectral characteristic corresponding to the spectral characteristic of a specific one of plural output signals to be outputted via the branch. Each branch may contain an active element, such as an amplifier, which is activated for outputting a signal, and which is deactivated for when node signal is to be outputted. A switchable impedance circuit is included within each of the branches to present a substantially constant impedance characteristic to the bridge, independently of whether the bridge amplifier is activated or deactivated. The local oscillator may provide plural frequencies, as by use of a variable-frequency oscillator or by use of plural oscillators, to place an output signal within the frequency band of a specific one of the output branches.
摘要翻译： 变频器采用诸如场效应晶体管（FET）的开关元件的平衡桥式混频器，其中本地振荡器向晶体管的栅极端子提供控制信号。 中频（IF）或射频（RF）的载波被调制用于数据通信，并被应用于桥的备用节点。 剩余的桥接节点向输出电路的各个分支提供输出信号。 输出电路的每个分支都具有带通滤波器，该带通滤波器具有对应于要通过分支输出的多个输出信号中的特定一个的频谱特性的频谱特性。 每个分支可以包含有源元件，例如放大器，其被激活用于输出信号，并且当节点信号被输出时被去激活。 每个分支中包括可切换阻抗电路，以向桥提供基本上恒定的阻抗特性，而不管桥式放大器是启动还是停用。 本地振荡器可以通过使用可变频率振荡器或通过使用多个振荡器来提供多个频率，以将输出信号放置在特定一个输出分支的频带内。
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