CC1190 with separate LNA and PA

[estratos]

CC1101 with separate LNA and PA

I want to develop a bi-directional radio based on TI's CC1101 (868 MHz) and MiniCircuit's PSA4-5043+ (or RFMD's SPF5043Z). PSA4-5043+ and SPF5043Z are Low Noise Amplifiers with a very good gain and low noise figure. I want the radio to be half-duplex and, at the same time, provide some Tx amplification capabilities so I'm thinking in developing a circuit with the architecture shown in the attached diagram.

I know that using the CC1190 is the more natural way to go but CC1190's LNA provides only +7 dB gain at 868 MHz whilst the mentioned LNA's provide near +20 dB.

As the power amplifier I'm not decide yet but I could give the PSA4-5043+ also a try as the Tx amplifier. On the switching side, I'm now looking at MiniCircuit's MSWT-4-20+.

What do you think about the proposed circuit? Have you any recommendation?
Can you recommend me some other switching IC (with better insertion loss)?

Thanks in advance for your time and ideas.

 

[BigBoss]

I suggest you to add additional switch after PA and LNA to able to share the same antenna if the TX and RX frequencies are same.
You may use PIN diode switch instead of expensive RF switches between IN/OUT stages and transceiver because you should turn off the LNA while trnasmitting mode and PA while receiving mode.You don't need too much isolation at this interstage step. I also recommened is to use a LP/BP filter after PA to supress unwnated harmonics and interferes.You may do it for LNA too.So using a single balun will have less loss.

 

[biff44]

you might need to either 1)tun off the DC power to the power amp when receiving, or 2) have a very high isolation switch---IF you decide to use one antenna.

 

[estratos]

Thanks guys, and sorry for the wrong title (already edited). I really meant CC1101 instead of CC1190.