Operating point setting of an amplifier
Embodiments related to the setting of an operating point of an amplifier are described and depicted.
1 . A method comprising:
generating a baseband signal;
generating a radio frequency signal based on the baseband signal;
receiving the radio frequency signal by an amplifier to generate an amplified radio frequency signal;
generating a down-converted signal based on the amplified radio frequency signal; and
setting the operating point of the amplifier based on the baseband signal and the down-converted signal.
2 . The method according to claim 1 , wherein the radio frequency signal is generated by modulating a first carrier signal with a first frequency by the baseband signal and wherein the down-converted signal is generated by demodulating a signal derived from the amplified radio frequency signal by using a second carrier signal with the first frequency.
3 . The method according to claim 1 , wherein setting the operating point of the amplifier is based on comparing the baseband signal and the down-converted signal.
4 . The method according to claim 3 , wherein comparing the baseband signal and the down-converted signal is based on an analysis of the difference between the baseband signal and the down-converted signal.
5 . The method according to claim 4 , wherein comparing the baseband signal and the down-converted signal is based on an analysis of an Error Vector Magnitude (EVM) between the baseband signal and the down-converted signal.
6 . The method according to claim 1 , wherein setting the operating point comprises setting a bias current and/or a bias voltage of the amplifier based on the baseband signal and the down-converted signal.
7 . The method according to claim 6 , wherein setting the operating point comprises using data provided by sensors.
8 . The method according to claim 7 , wherein the sensors are temperature sensors and/or voltage and/or current sensors.
9 . A device comprising:
a modulator configured to generate a radio frequency signal based on a baseband signal;
an amplifier configured to receive the radio frequency signal and to output an amplified radio frequency signal;
a demodulator configured to generate a down-converted signal based on the amplified radio frequency signal; and
a control circuit configured to receive the down-converted signal and the baseband signal to set the operating point of the amplifier.
10 . The device according to claim 9 , wherein the modulator is configured to modulate a first carrier signal with a first frequency by the baseband signal and wherein the demodulator is configured to generate the down-converted signal from a modulated second carrier signal with the first frequency.
11 . The device according to claim 9 , wherein the control circuit is configured to compare the baseband signal and the down-converted signal.
12 . The device according to claim 9 , wherein the control circuit is configured to analyze the Error Vector Magnitude (EVM) between the baseband signal and the down-converted signal.
13 . The device according to claim 9 , wherein the control circuit is configured to set the operating point of the amplifier by setting a bias current and/or a bias voltage of the amplifier.
14 . A method comprising
receiving a radio frequency signal by an amplifier;
generating an amplified radio frequency signal by the amplifier;
setting a value of at least one parameter to control the operating point of the amplifier; and
stepwise modifying the value of the at least one parameter from a first value to a second value wherein the power of the amplified radio frequency signal is substantially maintained.
15 . The method according to claim 14 wherein stepwise modifying comprises
changing the value of the at least one parameter with a first step size; and
changing the value of the at least one parameter with a second step size.
16 . The method according to claim 14 wherein the parameter is a bias current and/or a bias voltage of the amplifier.
17 . The method according to claim 14 , further comprising:
determining whether a quality of the amplified radio frequency signal is below a threshold, if it is determined that the quality of the amplified radio frequency signal is below the threshold, further modifying the at least one parameter value such that the quality of the amplified radio frequency signal is at a level above the threshold.
18 . The method according to claim 17 wherein the stepwise modifying and the further modifying comprises
changing the value of the at least one parameter with a first step size; and
changing the value of the at least one parameter with a second step size.
19 . The method according to claim 17 wherein the quality of the amplified radio frequency signal is the amplitude distortion (AM/AM) and/or phase distortion (AM/PM) of the amplifier.
20 . The method according to claim 17 wherein the quality of the amplified radio frequency signal is the adjacent channel leakage ratio (ACLR) within the amplifier.
21 . The method according to claim 17 wherein after the further modifying of the at least one parameter, the amplified radio frequency signal is generated for a predetermined time interval with the level above the threshold.
22 . The method according to claim 17 , wherein the stepwise modifying and the further modifying is repeated after the end of the time interval.
23 . A communication system comprising:
a transmitter, the transmitter comprising:
a modulator configured to provide a radio frequency signal based on a baseband signal;
an amplifier configured to receive the radio frequency signal and to output an amplified radio frequency signal;
circuitry configured to derive a first signal from the amplified radio frequency signal;
a demodulator configured to receive the first signal and to generate a down-converted signal; and
a controller to control the operating point of the amplifier based on the baseband signal and the down-converted signal.
24 . A device comprising
an amplifier;
a feedback loop to control a setting point of the amplifier, the feedback loop comprising a demodulator to generate a down-converted signal based on an output signal of the amplifier.