US6054894A — Digital control of a linc linear power amplifier

Claim 1

Independent Claim 116 words

In a LINC power amplifier, an adaptive method for compensating for an unwanted difference between analog signal paths, comprising: (a) separating an input transmission signal into at least first and second component signals having envelopes of varying phase and substantially constant amplitude; (b) amplifying the component signals along respective first and second analog signal paths; (c) combining the component signals following amplification to produce an output signal; (d) monitoring and digitally processing at least (i) the component signals prior to amplification, and (ii) the output signal, to generate compensation parameters; and (e) modifying the first and second component signals prior to amplification thereof, based on the compensation parameters, to reduce distortion caused by said unwanted difference.

Claim 2

Dependent Claim 116 words

In a LINC power amplifier, an adaptive method for compensating for an unwanted difference between analog signal paths, comprising: (a) separating an input transmission signal into at least first and second component signals having envelopes of varying phase and substantially constant amplitude; (b) amplifying the component signals along respective first and second analog signal paths; (c) combining the component signals following amplification to produce an output signal; (d) monitoring and digitally processing at least (i) the component signals prior to amplification, and (ii) the output signal, to generate compensation parameters; and (e) modifying the first and second component signals prior to amplification thereof, based on the compensation parameters, to reduce distortion caused by said unwanted difference.

Claim 3

Dependent Claim 41 words

The method of claim 1, wherein step (d) comprises storing digital sequences of the output signal and of the component signals in a memory, and processing the sequences stored within the memory in a non-real-time mode to generate the compensation parameters.

Claim 4

Dependent Claim 28 words

The method of claim 2, wherein step (d) comprises processing the sequences at a digital processing rate which is substantially less than a sampling rate of the sequences.

Claim 5

Dependent Claim 29 words

The method of claim 1, wherein step (d) comprises implementing at least one of the following digital filtering algorithms to generate the compensation parameters: LMS, RLS, Kalman, Extended Kalman.

Claim 6

Dependent Claim 29 words

The method of claim 1, wherein step (d) comprises storing a set of compensation parameters and a time stamp in a memory of the power amplifier for subsequent use.

Claim 7

Dependent Claim 31 words

The method of claim 1, wherein step (e) comprises digitally filtering the component signals to add at least one of propagation delay, amplitude gain and phase rotation to the component signals.

Claim 8

Dependent Claim 19 words

The method of claim 6, wherein step (e) comprises digitally filtering the component signals using finite impulse response filters.

Claim 9

Dependent Claim 26 words

The method of claim 1, wherein step (e) comprises adjusting gain settings of non-linear amplifiers that are used to amplify the first and second component signals.

Claim 10

Dependent Claim 54 words

The method of claim 1, further comprising applying training signals to the power amplifier when no input signal is present, and using the training signals in step (a) to generate compensation parameters, the method thereby enabling the compensation parameters to be updated when the power amplifier is not being used to transmit a signal.

Claim 11

Dependent Claim 50 words

The method of claim 9, wherein the step of applying training signals comprises generating first and second training signals that are in antiphase with one another so that the training signals substantially cancel each other when combined, the method thereby substantially inhibiting a transmission from the power amplifier during training.

Claim 12

Dependent Claim 64 words

The method of claim 9, wherein the step of applying training signals comprises applying a first training signal to the first analog signal path, and concurrently applying a second training signal that is orthogonal to the first training signal to the second analog signal path, the orthogonal first and second training signals allowing bulk imperfections in each analog signal path to be separately measured.

Claim 13

Dependent Claim 28 words

The method of claim 1, wherein step (b) comprises switching from a first set of compensation parameters to a second set of compensation parameters using an interpolation process.

Claim 14

Dependent Claim 36 words

The method of claim 1, further comprising the steps of: adaptively generating a numerical model of the first and second analog signal paths, and using the numerical model to generate an initial set of compensation parameters.

Claim 15

Dependent Claim 178 words

A power amplifier which receives a bandlimited input transmission signal and provides an output transmission signal, wherein the output transmission signal is a substantially linear amplified representation of the input transmission signal, the amplifier comprising: a signal component separator that decomposes the input transmission signal into at least a first component signal and a second component signal, wherein each component signal has a substantially constant amplitude and a varying phase; first and second analog signal paths along which the first and second component signals are respectively amplified; a combiner that receives and combines the first and second component signals following amplification thereof to compose the output transmission signal; a compensation signal processor that digitally modifies at least one of the first component signal and the second component signal prior to amplification to compensate for unwanted differences between the first and second analog signal paths, the compensation signal processor modifying the at least one component signal based on compensation parameters; and a compensation estimator which adaptively generates the compensation parameters based on an observation of signals within the amplifier.

Claim 16

Dependent Claim 178 words

A power amplifier which receives a bandlimited input transmission signal and provides an output transmission signal, wherein the output transmission signal is a substantially linear amplified representation of the input transmission signal, the amplifier comprising: a signal component separator that decomposes the input transmission signal into at least a first component signal and a second component signal, wherein each component signal has a substantially constant amplitude and a varying phase; first and second analog signal paths along which the first and second component signals are respectively amplified; a combiner that receives and combines the first and second component signals following amplification thereof to compose the output transmission signal; a compensation signal processor that digitally modifies at least one of the first component signal and the second component signal prior to amplification to compensate for unwanted differences between the first and second analog signal paths, the compensation signal processor modifying the at least one component signal based on compensation parameters; and a compensation estimator which adaptively generates the compensation parameters based on an observation of signals within the amplifier.

Claim 17

Dependent Claim 44 words

The power amplifier of claim 14, further comprising a memory which stores sequences of samples of observed signals within the amplifier, and wherein the compensation estimator processes the samples stored within the memory in a non-real-time mode to generate updates to the compensation parameters.

Claim 18

Dependent Claim 47 words

The power amplifier of claim 14, further comprising a signal generator which generates training signals to stimulate the first and second analog signal paths when no input transmission signal is present, the training signals enabling the compensation estimator to generate updates to the compensation parameters between transmissions.

Claim 19

Dependent Claim 32 words

The power amplifier of claim 16, wherein the signal generator generates first and second training signals which are substantially in antiphase so that the training signals substantially cancel each other when combined.

Claim 20

Dependent Claim 25 words

The power amplifier of claim 14, further comprising a circuit which recovers energy associated with signals applied to the first and second analog signal paths.

Claim 21

Dependent Claim 26 words

The power amplifier of claim 14, wherein the first and second analog signal paths comprise respective non-linear amplifiers which amplify the first and second component signals.

Claim 22

Dependent Claim 25 words

The power amplifier of claim 19, wherein the compensation signal processor further compensates for the unwanted differences by adjusting gain settings of the non-linear amplifiers.

Claim 23

Dependent Claim 35 words

The power amplifier of claim 14, wherein the first and second analog signal paths comprise respective Class A, AB, B, C, D, E, F or S amplifiers which amplify the first and second component signals.

Claim 24

Dependent Claim 42 words

The power amplifier of claim 14, wherein the first and second analog signal paths further comprise respective up-converters which convert the first and second component signals to RF frequencies, and wherein the compensation signal processor compensates for distortions caused by the up-converters.

Claim 25

Dependent Claim 34 words

The power amplifier of claim 14, wherein the first and second analog signal paths further comprise analog quadrature (IQ) modulators, and the compensation signal processor further comprises first and second IQ modulator correction circuits.

Claim 26

Dependent Claim 29 words

The power amplifier of claim 14, wherein the compensation signal processor is capable of introducing propagation delays, amplitude gains and phase rotations to the first and second component signals.

Claim 27

Dependent Claim 53 words

The power amplifier of claim 14, wherein the compensation signal processor comprises a first multi-tap finite impulse response (FIR) filter which digitally filters the first component signal, and comprises a second multi-tap FIR filter which digitally filters the second component signal, the first and second FIR filters operating based on the compensation parameters.

Claim 28

Dependent Claim 37 words

The power amplifier of claim 14, wherein the compensation estimator generates the compensation parameters based on an observation of at least (i) the first and second component signals prior to amplification, and (ii) the output transmission signal.

Claim 29

Dependent Claim 29 words

The power amplifier of claim 14, wherein the compensation estimator implements at least one of the following digital filtering algorithms to generate compensation parameters: LMS, RLS, Kalman, Extended Kalman.

Claim 30

Dependent Claim 31 words

The power amplifier of claim 14, wherein the compensation estimator generates initial values of the compensation parameters using a numerical model of at least the first and second analog signal paths.

Claim 31

Dependent Claim 126 words

A power amplifier which receives an input transmission signal and provides an output transmission signal, wherein the output transmission signal is a substantially linear amplified representation of the input transmission signal, the amplifier comprising: means for separating the input transmission signal into a plurality of components signals, wherein each component signal has an amplitude envelope which varies in phase and is substantially constant in amplitude; means for adaptively modifying the component signals to generate compensated component signals, the means for adaptively modifying compensating for unwanted differences in analog signal paths along which the compensated component signals are amplified; means for amplifying the compensated component signals to generate amplified, compensated component signals; and means for combining the amplified, compensated component signals to generate the output transmission signal.

Claim 32

Dependent Claim 126 words

A power amplifier which receives an input transmission signal and provides an output transmission signal, wherein the output transmission signal is a substantially linear amplified representation of the input transmission signal, the amplifier comprising: means for separating the input transmission signal into a plurality of components signals, wherein each component signal has an amplitude envelope which varies in phase and is substantially constant in amplitude; means for adaptively modifying the component signals to generate compensated component signals, the means for adaptively modifying compensating for unwanted differences in analog signal paths along which the compensated component signals are amplified; means for amplifying the compensated component signals to generate amplified, compensated component signals; and means for combining the amplified, compensated component signals to generate the output transmission signal.

Claim 33

Dependent Claim 51 words

The power amplifier of claim 29, further comprising means for capturing and storing digital sequences of at least the output transmission signal and of the component signals, wherein the means for adaptively modifying processes the digital sequences to generate updates to compensation parameters that are used to modify the component signals.

Claim 34

Dependent Claim 33 words

The power amplifier of claim 30, wherein the means for adaptively modifying processes the stored sequences at a digital processing rate which is substantially less than a sampling rate of the observation signals.

Claim 35

Dependent Claim 45 words

The power amplifier of claim 29, further comprising a signal generation means which generates training signals to stimulate the analog signal paths when no input transmission signal is present, the training signals used by the means for adaptively modifying to make adaptive adjustments between transmissions.

Claim 36

Dependent Claim 18 words

The power amplifier of claim 29, further comprising a means for recovering energy associated with the component signals.

Claim 37

Dependent Claim 19 words

The power amplifier of claim 29, wherein the means for amplifying comprises non-linear amplifiers which amplify the component signals.

Claim 38

Dependent Claim 23 words

The power amplifier of claim 34, wherein the means for adaptively modifying comprises means for adaptively adjusting gain settings of the non-linear amplifiers.

Claim 39

Dependent Claim 32 words

The power amplifier of claim 29, wherein the means for amplifying comprises amplifiers which fall within at least one of the following classes: A, AB, B, C, D, E, F and S.

Claim 40

Dependent Claim 24 words

The power amplifier of claim 29, wherein the means for adaptively modifying is capable of independently modifying each of the plurality of component signals.

Claim 41

Dependent Claim 27 words

The power amplifier of claim 29, wherein the means for adaptively modifying is capable of introducing propagation delays, amplitude gains and phase rotations to the component signals.

Claim 42

Dependent Claim 31 words

The power amplifier of claim 29, wherein the means for adaptively modifying implements at least one of the following digital filtering algorithms to generate compensation parameters: LMS, RLS, Kalman, Extended Kalman.

Claim 43

Dependent Claim 42 words

The power amplifier of claim 29, wherein the means for adaptively modifying comprises a first multi-tap finite impulse response (FIR) filter which digitally filters a first component signal, and comprises a second multi-tap FIR filter which digitally filters a second component signal.

Claim 44

Dependent Claim 28 words

The power amplifier of claim 29, wherein the analog signal paths further comprise analog quadrature (IQ) modulators, and the means for adaptively modifying comprises IQ modulator correction circuits.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2003-04-25	2003-10-25	2004-04-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2007-04-25	2007-10-25	2008-04-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2011-04-25	2011-10-25	2012-04-25	$7700.00	Window Closed / Lapsed

Digital control of a linc linear power amplifier

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