Required RF Receiver Gain

[shico90]

Hello, We are working on LTE front end design and now we are trying to find the right methodology to find the required overall gain by the receiver. Can anyone help please?

 

[BradtheRad]

If you look at sensitivity specs for tuners, the unit is commonly microvolts. 1uV is typical. We can take this as the broadcast signal strength.

A receiver contains a power amplifier for the speakers. Typical listenable volume from a speaker is 1 VAC.

To obtain this you need to amplify voltage 1 million times. Probably 10 million, depending on what you want it to be able to deliver.

You will not do it with just one device. It will require 3 or 4 stages.

 

[RF_Jim]

Hello, We are working on LTE front end design and now we are trying to find the right methodology to find the required overall gain by the receiver. Can anyone help please?

Part of overall 'gain' by the receiver is determined by the overall environment the receive will operate in, and this includes the antenna gain, the free space as well as expected 'obstructed space' (multipath) path losses, the user device transmit power level, user device antenna gain (or loss), and finally what signal level is being presented to the demodulator stage and ADC (analog to digital converted) stage. Sometimes variable or selectable attenuators are needed for the stronger signals when user devices are close to the BS (base station) equipment.

Front end design will also involve 'dynamic range' capabilities (like 1 dB compression and IP3 etc) and losses before the first active amplifier, like filtering and maybe PIN diode switch, all these components have loss. One should know generally the architecture of the receiver (and system including the transmitter and how they 'share' the antenna) before proceeding to required gain, through using system-level simulation tools or simple speadsheet what-if scenarios with picked values for various stage-gain and noise figure values on through to the ADC stage ...

Jim

 

[RFDave]

Fortunately, for LTE, the minimum receive sensitivity is in one of the specifications, and so all you really need to do is figure out the required gain between the antenna connector (Which is specified in dBm, making life easy) and the ADC, probably 1 or 2 Volts peak to peak. Make sure you pay attention to the impedance levels to get your calculations correct. You probably need 30 to 40 dB of gain. Make sure you pay attention to the specified large signal performance to look at your AGC requirements.