Accurate transmit power measurement
View Patent ↗A method for power measurement includes applying a nonlinear function to a Radio Frequency (RF) signal that includes a modulated component and a spurious component, so as to produce a broadband signal that includes a Direct-Current (DC) component, a baseband component and one or more High-Frequency (HF) components. The broadband signal is Band-Pass (BP) filtered so as to produce a bandpass signal from which the DC and HF components are removed. Based on the bandpass signal, a power of the modulated component in the RF signal is estimated irrespective of the spurious component.
1. A method for power measurement, comprising:
applying a nonlinear function to a Radio Frequency (RF) signal that comprises a modulated component and a spurious component, so as to produce a broadband signal that comprises a Direct-Current (DC) component, a baseband component and one or more High-Frequency (HF) components;
Band-Pass (BP) filtering the broadband signal so as to produce a bandpass signal from which the DC and HF components are removed; and
based on the bandpass signal, estimating a power of the modulated component in the RF signal irrespective of the spurious component.
2. The method according to claim 1 , wherein BP filtering the broadband signal comprises Low-Pass (LP) filtering the broadband signal so as to produce a low-frequency signal from which the HF components are filtered out, and High-Pass (HP) filtering the low-frequency signal so as to produce the bandpass signal from which the DC component is removed.
3. The method according to claim 2 , wherein HP filtering the low-frequency signal comprises preserving the entire baseband component.
4. The method according to claim 2 , wherein HP filtering the low-frequency signal and estimating the power of the modulated component comprise applying digital processing to the low-frequency signal.
5. The method according to claim 1 , wherein estimating the power of the modulated component comprises estimating a DC level of the bandpass signal, which is indicative of the power of the modulated component.
6. The method according to claim 1 , wherein estimating the power of the modulated component comprises applying an additional nonlinear function and subsequently a Low-Pass (LP) filtering function to the bandpass signal.
7. The method according to claim 1 , wherein estimating the power of the modulated component comprises applying a predefined calibration factor to the estimated power.
8. An apparatus for power measurement, comprising:
a nonlinear element, which is configured to apply a nonlinear function to a Radio Frequency (RF) signal that comprises a modulated component and a spurious component so as to produce a broadband signal that comprises a Direct-Current (DC) component, a baseband component and one or more High-Frequency (HF) components;
Band-Pass (BP) filtering circuitry, which is configured to BP filter the broadband signal so as to produce a bandpass signal from which the DC and HF components are removed; and
a Power Detector (PD), which is configured to estimate a power of the modulated component in the RF signal irrespective of the spurious component by processing the bandpass signal.
9. The apparatus according to claim 8 , wherein the BP filtering circuitry comprises:
a Low-Pass Filter (LPF), which is configured to filter the broadband signal so as to produce a low-frequency signal from which the HF components are filtered out; and
a High-Pass Filter (HPF), which is configured to filter the low-frequency signal so as to produce the bandpass signal from which the DC component is removed.
10. The apparatus according to claim 9 , wherein the HPF is configured to preserve the entire baseband component.
11. The apparatus according to claim 9 , wherein the HPF and the PD are implemented by a digital processor.
12. The apparatus according to claim 8 , wherein the PD is configured to estimate the power of the modulated component in the RF signal by estimating a DC level of the bandpass signal, which is indicative of the power of the modulated component.
13. The apparatus according to claim 8 , wherein the PD comprises an additional nonlinear element that is configured to apply an additional nonlinear function to the bandpass signal, and a Low-Pass Filter (LPF) that is configured to filter the bandpass signal after processing by the additional nonlinear element.
14. The apparatus according to claim 8 , wherein the PD is configured to apply a predefined calibration factor to the estimated power.
15. A transmitter, comprising:
a Power Amplifier (PA), which is configured to amplify a Radio Frequency (RF) signal that comprises a modulated component and a spurious component; and
a Power Measurement (PM) unit, which is configured to apply a nonlinear function to the amplified RF signal so as to produce a broadband signal that comprises a Direct-Current (DC) component, a baseband component and one or more High-Frequency (HF) components, to Band-Pass (BP) filter the broadband signal so as to produce a bandpass signal from which the DC and HF components are removed, and to estimate a power of the modulated component in the RF signal irrespective of the spurious component by processing the bandpass signal.
16. The transmitter according to claim 15 , wherein the PM unit comprises:
a Low-Pass Filter (LPF), which is configured to filter the broadband signal so as to produce a low-frequency signal from which the HF components are filtered out; and
a High-Pass Filter (HPF), which is configured to filter the low-frequency signal so as to produce the bandpass signal from which the DC component is removed.