Direct conversion becomes a common practice for CMOS radio

Recently search the literature, found that now Zero-IF has became the common practice for CMOS radio implementation. Two years ago I was thinking that direct conversion is impossible....technology advance is really amazing!

Any other architecture seems promising? how about sub-sampling?

research is into sub sampling right now...

i know people doing it for their PhD's...

the trend -- less analog and more digital.

used signal processing to do everything, keep analog minimal.

sampling everywhere... TI is already doing it.

Wide bandwidth and spread-spectrum technique make it possible to employ direct downconversion receivers. The negative effect of DC offset and flicker noise is reduced to a negligiable level.

IEEE802.11a is very suitalbe for dir-con architecture to make a highly integrated, low power and low cost chipset.

But at this time, it looks that the only CMOS 802.11a product is from Atheros, who actually did not use the direct-conversion. Other comapnies, such as Broadcom, RFMD, Athena Semi, have publications using direct-conversion, but not a product. I guest direct-conversion still is a challenging task...

Nokia phones have used direct conversion on TX and RX for
about 5 years now. However the RFICs in this case are BiCMOS.
Others, such as Siemens with their Smarti DC chips do the same..