Method and apparatus for reducing off-channel interference produced by a linear transmitter

Claim 2

In a linear transmitter that includes an information signal source and a power amplifier having a varying load impedance, the linear transmitter utilizing a closed loop feedback path to maintain linearity, wherein the closed loop feedback path includes a loop phase adjusting circuit, a method for reducing off-channel interference comprising the steps of: A) providing a dynamically alterable parameter source; B) measuring the varying load impedance to produce a measured load impedance; C) inputting the measured load impedance to the dynamically alterable parameter source; D) producing, by the dynamically alterable parameter source, a loop phase adjustment value base on the measured load impedance; E) inputting the loop phase adjustment value to the loop phase adjusting circuit; and F) adjusting, by the loop phase adjusting circuit, a phase value for the closed loop feedback path based, at least in part, on the loop phase adjustment value.

Claim 3

In a linear transmitter that includes an information signal source and a power amplifier having a varying load impedance, the linear transmitter utilizing a closed loop feedback path to maintain linearity, and the closed loop feedback path including a loop phase adjusting circuit, a method for reducing off-channel interference comprising the steps of: A) providing a dynamically alterable parameter source; B) providing a training signal within a training interval; C) at times falling substantially within the training interval, measuring the varying load impedance to produce a measured load impedance; D) inputting the measured load impedance to the dynamically alterable parameter source; at times falling substantially outside the training interval, E) using the dynamically alterable parameter source to produce a loop phase adjustment value based on the measured load impedance; F) inputting the loop phase adjustment value to the loop phase adjusting circuit; and G) adjusting, by the loop phase adjusting circuit, loop phase of the closed loop feedback path based on the loop phase adjustment value, thereby reducing off-channel interference produced during the training interval and at times falling substantially outside the training interval.

Claim 4

In a linear transmitter that includes an information signal source and a power amplifier having a varying load impedance, the linear transmitter utilizing a closed loop feedback path to maintain linearity, and the closed loop feedback path including a loop phase adjusting circuit, a method for reducing off-channel interference comprising the steps of: A) providing a dynamically alterable parameter source; B) providing a training signal within a training interval; C) at times falling substantially within the training interval, measuring the varying load impedance to produce a measured load impedance; D) inputting the measured load impedance to the dynamically alterable parameter source; at times falling substantially outside the training interval, E) using the dynamically alterable parameter source to produce a loop phase adjustment value based on the measured load impedance; F) inputting the loop phase adjustment value to the loop phase adjusting circuit; and G) adjusting, by the loop phase adjusting circuit, loop phase of the closed loop feedback path based on the loop phase adjustment value, thereby reducing off-channel interference produced during the training interval and at times falling substantially outside the training interval.

Claim 5

The method of claim 2, wherein the closed loop feedback path further includes a loop gain adjusting circuit, the method further comprising the steps of: at times falling substantially outside the training interval, H) using the dynamically alterable parameter source to produce a loop gain adjustment value based on the measured load impedance; I) inputting the loop gain adjustment value to the loop gain adjusting circuit; and J) adjusting, by the loop gain adjusting circuit, loop gain of the closed loop feedback path based on the loop gain adjustment value, thereby reducing off-channel interference produced during the training interval and at times falling substantially outside the training interval.

Claim 6

The method of claim 2, wherein the linear transmitter further includes a signal level adjusting circuit, the method further comprising the steps of: at times falling substantially outside the training interval, H) using the dynamically alterable parameter source to produce a signal level adjustment value based on the measured load impedance; I) inputting the signal level adjustment value to the signal level adjusting circuit; and J) adjusting, by the signal level adjusting circuit, an amplitude of a signal produced by the information signal source based on the signal level adjustment value, thereby reducing off-channel interference produced during the training interval and at times falling substantially outside the training interval.

Claim 7

A linear transmitter that utilizes a closed loop feedback path to maintain linearity, the closed loop feedback path including an amplifier that is terminated with a radiating load element during normal operation, the linear transmitter comprising: a switch for terminating an output of the amplifier with a non-radiating loading circuit, wherein the non-radiating loading circuit comprises a load impedance synthesizer and a load measuring device; and means, operably coupled to the non-radiating loading circuit, for adjusting at least one loop parameter of the closed loop feedback path when the output of the amplifier is terminated with the non-radiating loading circuit.

Claim 8

A linear transmitter that utilizes a closed loop feedback path to maintain linearity, the closed loop feedback path including an amplifier that is terminated with a radiating load element during normal operation, the linear transmitter comprising: a switch for terminating an output of the amplifier with a non-radiating loading circuit, wherein the non-radiating loading circuit comprises a load impedance synthesizer and a load measuring device; and means, operably coupled to the non-radiating loading circuit, for adjusting at least one loop parameter of the closed loop feedback path when the output of the amplifier is terminated with the non-radiating loading circuit.

Claim 9

A linear transmitter that utilizes a closed loop feedback path to maintain linearity, the closed loop feedback path including an amplifier that is terminated with a radiating load element during normal operation, the linear transmitter comprising: a PIN diode and a biasing circuit for terminating an output of the amplifier with a non-radiating loading circuit, wherein the non-radiating loading circuit comprises an isolator and a constant loading element; and means, operably coupled to the non-radiating loading circuit, for adjusting at least one loop parameter of the closed loop feedback path when the output of the amplifier is terminated with the non-radiating loading circuit.

Claim 10

A linear transmitter that utilizes a closed loop feedback path to maintain linearity, the closed loop feedback path including an amplifier that is terminated with a radiating load element during normal operation, the linear transmitter comprising: a PIN diode and a biasing circuit for terminating an output of the amplifier with a non-radiating loading circuit, wherein the non-radiating loading circuit comprises an isolator and a constant loading element; and means, operably coupled to the non-radiating loading circuit, for adjusting at least one loop parameter of the closed loop feedback path when the output of the amplifier is terminated with the non-radiating loading circuit.

Claim 11

In a linear transmitter that includes an information signal source and a power amplifier having a varying load impedance, the linear transmitter utilizing a closed loop feedback path to maintain linearity, and the closed loop feedback path including a loop gain adjusting circuit, a method for reducing off-channel interference comprising the steps of: A) providing a dynamically alterable parameter source; B) providing a training signal within a training interval; C) at times falling substantially within the training interval, measuring the varying load impedance to produce a measured load impedance; D) inputting the measured load impedance to the dynamically alterable parameter source; at times falling substantially outside the training interval, E) using the dynamically alterable parameter source to produce a loop gain adjustment value based on the measured load impedance; F) inputting the loop gain adjustment value to the loop gain adjusting circuit; and G) adjusting, by the loop gain adjusting circuit, loop gain of the closed loop feedback path based on the loop gain adjustment value, thereby reducing off-channel interference produced during the training interval and at times falling substantially outside the training interval.

Claim 12

In a linear transmitter that includes an information signal source and a power amplifier having a varying load impedance, the linear transmitter utilizing a closed loop feedback path to maintain linearity, and the closed loop feedback path including a loop gain adjusting circuit, a method for reducing off-channel interference comprising the steps of: A) providing a dynamically alterable parameter source; B) providing a training signal within a training interval; C) at times falling substantially within the training interval, measuring the varying load impedance to produce a measured load impedance; D) inputting the measured load impedance to the dynamically alterable parameter source; at times falling substantially outside the training interval, E) using the dynamically alterable parameter source to produce a loop gain adjustment value based on the measured load impedance; F) inputting the loop gain adjustment value to the loop gain adjusting circuit; and G) adjusting, by the loop gain adjusting circuit, loop gain of the closed loop feedback path based on the loop gain adjustment value, thereby reducing off-channel interference produced during the training interval and at times falling substantially outside the training interval.

Claim 13

In a linear transmitter that includes an information signal source, a power amplifier having a varying load impedance, and a signal level adjusting circuit, the linear transmitter utilizing a closed loop feedback path to maintain linearity, a method for reducing off-channel interference comprising the steps of: A) providing a dynamically alterable parameter source; B) providing a training signal within a training interval; C) at times falling substantially within the training interval, measuring the varying load impedance to produce a measured load impedance; D) inputting the measured load impedance to the dynamically alterable parameter source; at times falling substantially outside the training interval, E) using the dynamically alterable parameter source to produce a signal level adjustment value based on the measured load impedance; F) inputting the signal level adjustment value to the signal level adjusting circuit; and G) adjusting, by the signal level adjusting circuit, an amplitude of a signal produced by the information signal source based on the signal level adjustment value, thereby reducing off-channel interference produced during the training interval and at times falling substantially outside the training interval.

Claim 14

In a linear transmitter that includes an information signal source, a power amplifier having a varying load impedance, and a signal level adjusting circuit, the linear transmitter utilizing a closed loop feedback path to maintain linearity, a method for reducing off-channel interference comprising the steps of: A) providing a dynamically alterable parameter source; B) providing a training signal within a training interval; C) at times falling substantially within the training interval, measuring the varying load impedance to produce a measured load impedance; D) inputting the measured load impedance to the dynamically alterable parameter source; at times falling substantially outside the training interval, E) using the dynamically alterable parameter source to produce a signal level adjustment value based on the measured load impedance; F) inputting the signal level adjustment value to the signal level adjusting circuit; and G) adjusting, by the signal level adjusting circuit, an amplitude of a signal produced by the information signal source based on the signal level adjustment value, thereby reducing off-channel interference produced during the training interval and at times falling substantially outside the training interval.