定义
射频信号发生器是射频、微波测试和开发领域必须用到的一种基本测试仪器。它与频谱仪、示波器等其他设备不同,信号发生器不进行任何指标的测量,而是为其他测试仪器提供正确的测试条件,以便测量被测单元的输出信号。
类型
射频信号发生器主要包括两种基本类型:(1)Free running射频信号发生器;(2)合成射频信号发生器。具体如下图所示:
主要组件
振荡器:射频信号发生器中最重要的部件,接收来自控制器的命令设置输出所需的频率
放大器:将振荡器输出信号放大到特定的功率电平
衰减器:有助于确保射频信号发生器输出端的阻抗匹配,同时可以通过自动调整衰减器来保证信号源的输出电平稳定精度,一般衰减器的增量步进为0.1dB
控制:射频信号发生器的控制中心,控制输出频率、输出功率、调制方式,同时也可以接收远程控制命令。
功能
频率范围:射频信号发生器能输出的频率区间,一般频率范围越宽越好,但是价格也就越贵,目前一般后1G,3G,6G和更高。
输出电平:输出电平包括输出的范围和精度,范围一般信号源在-140~+20dBm,精度在±0.5dB,步进0.1dB。
调制:随着移动通信等应用的调制格式变得越来越复杂,因此对信号发生器的要求也越来越高,需要信号源能进行模拟、数字调制,如AM\FM\QPSK\QAM等。
definition
Rf signal generator is a kind of basic test instrument which must be used in RF and microwave test and development field. It is different from spectrum analyzer, oscilloscope and other equipment, signal generator does not measure any index, but provides correct test conditions for other test instruments, so as to measure the output signal of the measured unit.
type
Rf signal generator mainly includes two basic types: (1) Free running RF signal generator; (2) synthetic RF signal generator. The details are shown in the following figure:
Main component
Oscillator: The most important component of an RF signal generator that receives commands from the controller to set the frequency required for output
Amplifier: amplifies the oscillator output signal to a specific power level
Attenuator: It helps to ensure the impedance matching of the output end of the RF signal generator. At the same time, it can automatically adjust the attenuator to ensure the stability accuracy of the output level of the signal source. Generally, the incremental step of the attenuator is 0.1dB
Control: The control center of the RF signal generator, which controls the output frequency, output power, modulation mode, and can also receive remote control commands.
function
Frequency range: the frequency range that the RF signal generator can output. Generally, the wider the frequency range, the better, but the more expensive the price is. At present, the general after 1G, 3G, 6G and higher.
Output level: The output level includes the output range and accuracy. The range is generally from -140 to +20dBm, the accuracy is ±0.5dB, and the step is 0.1dB.
Modulation: As the modulation format of mobile communication and other applications becomes more and more complex, so the demand for signal generator is also higher and higher, the need for signal source can be analog, digital modulation, such as AM\FM\QPSK\QAM, etc.