Trying to design lattice phase equalizer
时间：04-06
整理：3721RD
点击：
Hi all,
I am currently working on a Localized Harmonic Motion experiment (a subdivision of High Intensity Focused Ultrasound (HIFU) research) and stumbled upon a puzzle. The system introduces several types of noise, including harmonics brought upon by the focused ultrasound transducer (which operates at a fundemental frequency of 1.1575MHz). In order to filter out most of the noise analog filters were designed (and to maintain headroom in the CPU and GPU for cross-correlation calculations), which unfortunately introduce phase shifts to the acquired signal.
I am attempting to design an allpass filter to remedy this issue. I would like to design an analog (passive elements only) lattice phase equalizer to mitigate the effects of the phase shifts incurred by the filters. I have found the topology but cannot seem to get a good design (I always get attenuation with the phase-shift, which means my equalizer acts more like a low pass filter).
Would anyone have any suggestions as to how to properly design such an equalizer (or any other type of equalizer), or maybe of another way to go about solving this issue?
Another method we are thinking of is to implement such an equalizer digitally through MATLAB (which is already used for the cross-correlation calculations), but this may result in more required headroom in terms of memory.
Any help is greatly appreciated.
---also, any SPICE circuits would be of great help! (I use LTSpice)
I am currently working on a Localized Harmonic Motion experiment (a subdivision of High Intensity Focused Ultrasound (HIFU) research) and stumbled upon a puzzle. The system introduces several types of noise, including harmonics brought upon by the focused ultrasound transducer (which operates at a fundemental frequency of 1.1575MHz). In order to filter out most of the noise analog filters were designed (and to maintain headroom in the CPU and GPU for cross-correlation calculations), which unfortunately introduce phase shifts to the acquired signal.
I am attempting to design an allpass filter to remedy this issue. I would like to design an analog (passive elements only) lattice phase equalizer to mitigate the effects of the phase shifts incurred by the filters. I have found the topology but cannot seem to get a good design (I always get attenuation with the phase-shift, which means my equalizer acts more like a low pass filter).
Would anyone have any suggestions as to how to properly design such an equalizer (or any other type of equalizer), or maybe of another way to go about solving this issue?
Another method we are thinking of is to implement such an equalizer digitally through MATLAB (which is already used for the cross-correlation calculations), but this may result in more required headroom in terms of memory.
Any help is greatly appreciated.
---also, any SPICE circuits would be of great help! (I use LTSpice)
what is your operating frequency range, input and output impedance, and how much phase shift +/- do you have to compensate for?
the passband of the imaging transducer is 5.28MHz to 9.3Mhz, I/O impedance is 50ohms and the phase shift needed would be around the +90 to 270 degree range (not definite yet, the filters aren't completely designed yet, because if a proper equalizer is not built, it is not feasible to use all of the filters).