Differential IF amplifier for transmitter

Sounds like you need an amplifier with real input and output impedances (e.g. vs. an amplifier with relatively high input impedance and low ouitput impedance).  Take a look at AD8352 which has fixed pin-strapped gain or AD8375 which has digitally programmable gain and can be configured to have 150 ohm input and output impedance. A devices like ADL5565 could also work but its output impedance is low. So you might have to add (lossy) output series resistance to provide matching to your next stage. Do you really need to match to 50 ohms throughout the circuit?

Thanks for the reply. It is not necessary to match to 50ohm throughout the circuit. AD8375 seems to be able to do the trick.

On a separate question, I couldn't find a up-conversion mixer on the website. The requirement for the mixer will be IF 164MHz, RF from 700MHz to 2500MHz. Can you recommend one? 

Thanks.

ADL5801 can also work as an up-converting mixer.  From page 18 onwards (Rev C datasheet), there are some plots of performance in up-converting modes. These plots can be a bit confusing because the input intermediate frequency is being applied to the mixer's RFIP and RFIN and the up-converted output frequency comes out on IFON and IFOP.

thanks for the help. I will take a look at ADL5801.

The ADL5534 might work for your application. It is a dual IF gain block, each amplifier having a 50 ohm characteristic impedance. It has 20 dB of gain, 20.6 dBm, P1 dB and 39 dBm, OIP3, at 190 MHz.

http://www.analog.com/static/imported-files/data_sheets/ADL5534.pdf