On 08/02/2015 03:01 PM, Samith Abeywickrama wrote:
Hi,
I am confused with 89dB tx gain of USRP B210 and what is the meaning
of 89dB gain? How this value relates to maximum output of 50mW in
B210? Because this value is too much high, as a example: If the RF
output power of AD9361 agile transceiver is -29dBm and after we apply
89dB gain, transmit power should be 50dbm, But 50dBm is too much
higher than 50mW.
--
Best Regards!
Samith
The maximum output power of the AD9361 is about +17dBm.
Gain control is implemented as attenuators in the gain chain, so that
89dB of gain-control range should be applied to the maximum output power
at any
given frequency, so that a setting of 0dB gain means that,
notionally, your output power is +17dBm - 89dB = -72dBm, and at 89dB
"gain", your output
power would be +17dBm.
In RF circuits, it's very typical to use variable attenuators to effect
gain control, so that the individual gain stages operate at fixed bias
and matching
levels, and the inter-stage attenuators collectively effect some
range of gain control for the entire chain.
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