Multi-stage bandpass low-noise amplifier
A multi-stage low-noise amplifier (LNA) device with a band pass response includes a first LNA in series with a second LNA. The device further includes multiple outputs coupled to the second LNA. Each of the outputs is capable of being active at the same time. The device further includes a high pass filter coupled between the first LNA and the second LNA.
1. A multi-stage low-noise amplifier (LNA) device with a band pass response, comprising:
a first LNA stage in series with a second LNA stage, the first LNA stage having a plurality of inputs, each of the plurality of inputs corresponding to a different frequency band, the second LNA stage comprising a plurality of parallel LNAs;
a plurality of outputs coupled to the second LNA stage, each of the plurality of outputs capable of being active at a same time; and
a high pass filter coupled between the first LNA stage and the second LNA stage.
2. The device of claim 1 , in which the high pass filter is passive.
3. The device of claim 1 , in which the high pass filter is active.
4. The device of claim 3 , in which the high pass filter comprises a low pass filter and an inverting amplifier.
5. The device of claim 4 , in which the high pass filter comprises a plurality of low pass filters (LPFs).
6. The device of claim 1 , in which the high pass filter comprises a resistor capacitor (RC) circuit.
7. The device of claim 1 , in which the first LNA stage and the second LNA stage are inductor-less.
8. The device of claim 1 , in which each of the plurality of outputs corresponds to a different carrier.
9. The device of claim 1 , in which only one input is active at one time.
10. The device of claim 1 , in which the high pass filter is configured to present a high shunt impedance at in-band frequencies and a low shunt impedance at low frequencies.
11. A method of wireless communication, comprising:
amplifying multiple inputs at a first stage of a multi-stage low-noise amplifier (LNA), each of the multiple inputs comprising a different radio frequency band;
low pass filtering, through two low pass filters in series, an output from the first stage of the multi-stage LNA to generate a low pass filtered output;
amplifying and inverting the low pass filtered output to produce an inverted output; and
combining the inverted output with the output from the first stage to generate a combined output to cancel low frequency components of the output of the first stage and produce a band pass response.
12. The method of claim 11 , further comprising amplifying the combined output at a second stage of the multi-stage LNA to generate multiple second stage outputs, each of the second stage outputs corresponding to a different carrier.
13. A multi-stage low-noise amplifier (LNA) apparatus with a band pass response, comprising:
means for amplifying a plurality of inputs at a first stage of the multi-stage LNA, each of the plurality of inputs comprising a different radio frequency band;
means for low pass filtering, through two low pass filters in series, an output from the first stage of the multi-stage LNA to generate a low pass filtered output;
means for amplifying and inverting the low pass filtered output to produce an inverted output; and
means for combining the inverted output with the output of the first stage to generate a combined output to cancel low frequency components of the output of the first stage.
14. The apparatus of claim 13 , further comprising means for amplifying the combined output at a second stage of the multi-stage LNA to generate a plurality of second stage outputs, each of the second stage outputs corresponding to a different carrier.
15. The apparatus of claim 13 , further comprising means for suppressing the output from the first stage.
16. The apparatus of claim 13 , further comprising means for suppressing the combined output at a second stage.
17. The apparatus of claim 16 , in which some frequencies are unaffected.