Seeking Analog Transceiver

Jonny,

Consider using the LMX2531 that can generate an output.  For the modulation, you can apply it to the loop filter voltage or the input reference signal.  If you need something with higher bandwidth, consider the LMX2541 or LMX2581.

Regards,

Dean

what's the simplest way to turn this into a radio transceiver? can i connect it directly to an antenna? do i need a front-end, booster, or rf amplifier?

in the product page, i clicked Wireless Infrastructure: Direct Conversion RX/TX but that returned a dead-link.

thx!

Dean, by "bandwidth", do you mean the maximum bandwidth of the modulation?

I need a modulation bandwidth equivalent to at least 16 bits of resolution (but again my input will be analog).

Also, i having trouble finding that the maximum input frequency on the LM2531 datasheet. Is that the "PLL Input Frequency"? If so, this chip might not work: my input frequency will range from 20Hz to 20Khz. Can this chip support that?

thx!

why would i NOT want to use the LMX2430 for this?

http://www.ti.com/product/LMX2430

Another transceiver option is the TRF2443.  This operates at low frequency 340 MHz TX, 120 MHz RX.  The device includes integrated PLL/VCO for full transceiver operation.

Another option to consider is the CC2530 or the like.  These are low power RF transcievers.  You can check out these devices on www.ti.com for more information.

--RJH

Thx, RJH.

Question, how does the TRF2443 transmit on one frequency, and receive on a different frequency?

thx!

ps, can't use the CC2530 family-- no direct VCO input.

The TRF2443 incoporates separate internal PLL/VCOs that drive the IF modulator/demodulator LO input.  Because there are separate programmable PLL/VCOs for the TX and RX respectively, the frequencies are independent.

--RJH

yes, i understand that.

my question is, how can one TRF2443 transmit to another TRF2443, if the transmit and receive frequencies are different?

thx

Ok, if that is the intent then the TX and RX of different devices need to be aligned.  This is possible, but there will be a limited frequency range due the tuning range of the synthesizers.

Let's call the forward link the path that TX from one TRF2443 to the RX of a second.  Similarly, the reverese link is the path from the second to first.  It is possible to set all the frequencies to 330 MHz such that one device can TX and the other can RX.  Then the forward and reverse paths would be operating at the same frequencies which may not be desirable.  In this case, it is possible to slightly skew the operating frequency just out of tuning range of one of the RF synthesizers (the other one skews the same but will be in the tuning range) and thus operate one of the links at a slightly different frequency.  Note, the tuning range is what we guarantee will work, but generally the range can be extended reliability at room temperature.

--Russell

"It is possible to set all the frequencies to 330 MHz such that one device can TX and the other can RX."

yes, i see from the product description that it can transmit and receive at 330 mHz. But, most of the transmit and receive range does not overlap.

Transmit range: 165–175 MHz / 330–350 MHz

Receive range: 140–165 MHz / 280–330 MHz

What's the use-case for this? What is the purpose of a transceiver which transmits mostly at frequencies that itself cannot receive?

thx