The Design Of Arbitrary Waveform Generator Channel Circuit With 5GHz Bandwidth

Arbitrary waveform generators can construct real environment signals and are widely used in civil and military testing fields.The conditioning channel is located at the end of the instrument's signal path,and adjusts the amplitude,DC offset,and filtering of the waveform signal output by the arbitrary waveform synthesis module,so that the conditioned signal meets the requirements of the instrument's output index.In this paper,aiming at improving the technical indicators such as bandwidth,waveform purity and signal amplitude adjustment range,an arbitrary waveform generator conditioning channel with 12GSPS sampling rate,5GHz bandwidth and multiple output modes is designed.The main research contents are as follows:1.The overall scheme design and implementation of the channel circuit.By analyzing the amplitude and spectral characteristics of the input signal of the conditioning channel,aiming at the problems of small adjustable range of amplitude,adjustable bias voltage and stray components in the input signal,the scheme demonstration and device selection are carried out through the modules of amplification,attenuation,DC bias and filtering in the channel.At the same time,based on the commonality of the output structure of DC coupling and AC coupling,the circuit is simplified,and the channel attenuation circuit and filter circuit that satisfy the indicators of the two output modes are designed,and the DC and AC coupling including the amplifier circuit and the DC bias circuit are designed respectively.aisle.For the synthetic output of fast-edge square wave signals,a separate fast-edge square wave channel is designed using high-speed comparators and high-speed logic gates.According to the switching requirements of each channel circuit,a three-level switching circuit is designed using MEMS switches and high-frequency relays.2.Design and realization of multi-output mode conditioning channel circuit.Aiming at the image frequency components existing in the output signal of the arbitrary waveform synthesis module and the noise and other stray components introduced by active devices such as amplifiers in the conditioning channel,an eight-stage LTCC filter and ADGM1304 type MEMS switch are used to design a 5GHz broadband filter network,which achieves a 5GHz bandwidth.Sine signal output with up to-80d Bc spurious free dynamic range in bandwidth.According to the requirement of channel amplitude attenuation,the PE43704 digital step attenuator is used to design the attenuation circuit whose attenuation range is 0?32d B step-adjustable.According to the index requirements of the output amplitude range of-20d Bm?+10d Bm within the 50MHz?5GHz bandwidth of the AC coupling channel,the RF amplifier HMC8411 and the channel attenuation circuit are used to design the AC amplitude coarse adjustment circuit.Aiming at the index requirements of the output amplitude range of 25m V_PP?5V_PP in the DC?5GHz bandwidth of the DC coupling channel,the LMH5401 differential amplifier,the THS3491operational amplifier and the channel attenuation circuit are used to design the amplitude coarse adjustment circuit.3.Realize the generation and conditioning of fast-edge square waves.For the generation of the differential fast-edge square wave signal,the high-speed comparator ADCMP580 device is used to generate a differential square wave signal with a fixed duty cycle of 50%at the CML level.And perform clamping processing at the output end to obtain a fixed-amplitude fast-edge square wave signal whose rise/fall time is less than110ps.For the amplitude and DC offset adjustment of the fast-edge square wave signal,the differential amplifier LMH5401 and the voltage-controlled attenuator HMC346 are used to realize the precise adjustment and coarse adjustment of the fast-edge square wave amplitude;The DC bias adjustment of the fast-edge square wave is completed by superimposing the DC voltage,and the output of the fast-edge square wave signal with an amplitude of 25m V_PP?750m V_PP and a DC bias voltage of-0.5V?+0.5V is realized.The test results show that the 5GHz bandwidth arbitrary waveform conditioning channel designed in this paper adopts the DC coupling and AC coupling output methods to achieve 25m V_PP?5V_PP amplitude,-5V?+5V DC bias,maximum-80d Bc spurious free dynamic range and 110ps rise.The design is at the leading level in China,which is comparable to the conditioning channel level of foreign Keysight M8190A products.