[Question] Hartley and Weaver Architecture

Hi all,

i'm wondering in these two architectures, why not to put one low pass filter after the IF output instead of putting two low pass filters after the first two mixers. so one low pass filter will be saved.

thanks in advance

c.m.

1. You usually need the IF output in quadrature for modern modulation schemes.

2. In the Weaver receiver you cannot do that because you need to attenuate the secondary image.

thank you.

1). but i'm refering to the simple receiver architectures which are discussed in Razavi's book; there is no I/Q

2). i suppose in the weaver receiver, BP filters are needed to filter out the secondary image; with LP filters, there is no way to filter out the secondary image, then why not put one LP filter after the IF signal?

thanks,

c.m.