Design Of Double Channel Broadband Signal Generator

With the development of modern communication technology, more requirements were brought up about the signal source's output waveform class, frequency range,resolution ratio,precision and so on; expecially the high frequency signal source was known as heart of modern electronic system.For technical requirements and characteristics of signal generator in the above areas, this paper propose a scheme which using ARM7 series chip LPC2132 as the core of control circuit, employing circuit device AD9954 based on advance DDS technology as waveform generator chip, seven first-order low-pass filter with good amplitude-frequency characteristics carrying onlow-pass filter, high cost performance AD8130,THS3091 setting up DC bias and signal amplitude, attenuation networks realizing signal attenuation. A two-channel broadband 160MHz signal generator was designed.The hardware circuit of the signal generator included control unit,waveform generator unit and conditioning unit. The control unit used LPC2132 as control circuit core, utilizing its rich I/O resource and powerful event management module to real-time control every peripheral circuit and control the various parameters required for the waveform output, realizing the system's function.Waveform generator unit adopted AD9954 as its core device to generate simple high speed sine waveform and square wave, and used software to realize high speed modulation such as amplitude,frequency,phase modulation and frequency hopping; in addition, the AD9954 chip can provide user-defined linear sweep operate mode.Conditioning unit mainly included filtering , power amplification and attenuation part. The filtering was realized by passive low-pass filter circuit which made up the important part in the signal modulation circuit of the signal generator. Attenuation network realized 0dB~12dB attenuation characteristic; all nonstandard resistance used in the attenuation network design employed two 1206 footprint resistance connected in parallel.According to the actual usage and the specific technical requirements, the thesis detailed analysis circuit design theory, decide each componments type and value. Redraw the schematic diagram and PCB.By serial successive debug, signal generator module has been used in a test system.