RTOS/TRF37T05: TRF37T05IRGER ＆ TRF3705IRGER difference？

The only difference between the TRF37T05 and the TRF3705 is how the power down function operates. The 'T05 is specifically suited for TDD applications. The power down function on the 'T05 does not power down the entire chip, it only powers down the modulator portion of the chip and not the LO drive circuitry. This is done to maintain adjusted carrier feed-through in TDD operation when the device will be toggling between on and off. The specs between the '05 and 'T05 are the same except for the power down current. There is no need to use the 'T05 unless you are operating in TDD mode with zero-IF architecture.

--RJH

Hi RJ：

Thanks for you answer, and ..

1. Then IF I use TDD mode-zero-if architecture and TRF3705 at the same time, what bad results will there be?

2. Then IF I dont use TDD mode-zero-if architecture ,but use the TRF37T05,what bad results will there be?

thanks again!

1. Then IF I use TDD mode-zero-if architecture and TRF3705 at the same time, what bad results will there be?

RJH>> The parameter that will be impacted in this scenario is *adjusted* carrier feed-through performance. Typically, you can adjust the DC offset balance in the I/Q paths to suppress the carrier (i.e. LO) component. In the "regular" '05 the toggling of the power down in TDD operation will perturb the adjustment and the carrier component will not be fully suppressed. By the time it has recovered, the toggle has happened again (for normal TDD operation). In essence, the carrier feed-through performance does not have time to fully recover to optimized levels when the power down is continually toggled. The 'T05 solves this problem by not powering down the offending LO drive circuitry.

2. Then IF I dont use TDD mode-zero-if architecture ,but use the TRF37T05,what bad results will there be?

RJH>> No impact in this situation.