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Design >> RF Design >> why need low pass filter in image reject mixer
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Message started by sapphire on May 12^th, 2007, 11:20pm

Title: why need low pass filter in image reject mixer
Post by sapphire on May 12^th, 2007, 11:20pm

seems like the sum frequency components would also be rejected by the architecture.

Title: Re: why need low pass filter in image reject mixer
Post by carlgrace on Jun 1^st, 2007, 5:29am

The image's sum would be rejected but there would be a sum component in the output. Also, the summing circuit would have to be perfectly balanced for there not to be an issue of intermod.

Title: Re: why need low pass filter in image reject mixer
Post by loose-electron on Jun 5^th, 2007, 11:29am

agree with the above - In an ideal math only world, things can cancel perfectly. In a real world method, there will always be some junk there that was not cancelled out