Let's assume I'm talking about a typical single-antenna 5 GHz center-frequency 40 MHz bandwidth 802.11 receiver, but I'm interested more generally. What components in a wireless receiver draw the most power? And how do the power consumption of these components change as a function of bandwidth?
closed as too broad by Andy aka, PeterJ, Dmitry Grigoryev, uint128_t, Voltage Spike Sep 12 '17 at 19:56
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MOSFETs need high current to achieve high transconductance and thus low random noise. Also, for low distortion, low 2nd order and low 3rd order distortion, achieved by designing for high intercept-points 2nd and 3rd, you need high currents. Thus that front end amplifier (LNA) is the hot spot.
However, if you are in a strong-signal location with low interfering tones in nearby channels and low out-of-band blocker energy, the Receiver control logic may measure the BitErrorRate or the residual errors during the initial adaptive-equalization time, and decide the LNA current can be reduced.