Thanks I think your right about the shaping method. Iv been playing around with the TI app, but for the filter it generates it says that I need an op-amp with a minimum of about 82MHz GBW, could that be right, I haven't formally studied Active Filters yet but that figure seems rather high, The fastest Op-Amp I have is an NE5534(10MHz GBW) If I do need a faster opamp, which would you recommend?
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You can use a 200R (fig.11 in data sheet) the 500R pot is to adjust THD, though I have already tried varying the value in LTspice, Unfortunately It doesnt remove the glitch though, it just alters the shape of the wave. Thanks