Abstract: The variable power supply to an amplifier in an electrical circuit is dynamically controlled through the use of a lookup table responsive to one or more operating conditions of the electrical circuit. The lookup table is indexed by one or more of the operating conditions and the amount of amplification to be applied to an input signal to the amplifier is determined. One embodiment of the invention comprises a television transmitter circuit including a power amplifier circuit capable of amplifying a variable frequency COFDM or 8VSB input signal where the amount of amplification applied to the input signal is dynamically controlled through the use of a lookup table as a function of the frequency of the input signal.

Abstract: An RF wideband amplifier system is provided that includes an M way splitter for receiving an RF input signal and splitting same into M RF signals for respective application to M power amplifier modules PAM-1 to PAM-M that amplify the M signals and apply the amplified M signals to an M way combiner that applies an amplified RF signal to a load. A main controller provides an automatic level control reference signal, representative of the desired output power level of each of the power amplifier modules.

Abstract: A directional coupler comprises a coupler circuit board which is mounted substantially perpendicular to the surface of a parent circuit board. First and second upper traces are disposed on the opposing surfaces of the coupler circuit board. The coupling between the upper electrically conductive traces determines the odd mode impedance of the coupler. First and second lower traces are also disposed on opposing surfaces and connected to ground. The upper and lower traces are arranged such that the even mode of the impedance is determined by the coupling between the first upper trace and the second lower trace and the coupling between the second upper trace and the first lower trace.

Abstract: The variable power supply to an amplifier in an electrical circuit is dynamically controlled through the use of a lookup table responsive to one or more operating conditions of the electrical circuit. The lookup table is indexed by one or more of the operating conditions and the amount of amplification to be applied to an input signal to the amplifier is determined. One embodiment of the invention comprises a television transmitter circuit including a power amplifier circuit capable of amplifying a variable frequency COFDM or 8VSB input signal where the amount of amplification applied to the input signal is dynamically controlled through the use of a lookup table as a function of the frequency of the input signal.

Abstract: A directional coupler comprises a coupler circuit board which is mounted substantially perpendicular to the surface of a parent circuit board. First and second upper traces are disposed on the opposing surfaces of the coupler circuit board. The coupling between the upper electrically conductive traces determines the odd mode impedance of the coupler. First and second lower traces are also disposed on opposing surfaces and connected to ground. The upper and lower traces are arranged such that the even mode of the impedance is determined by the coupling between the first upper trace and the second lower trace and the coupling between the second upper trace and the first lower trace.

Abstract: An RF wideband amplifier system is provided that includes an M way splitter for receiving an RF input signal and splitting same into M RF signals for respective application to M power amplifier modules PAM-1 to PAM-M that amplify the M signals and apply the amplified M signals to an M way combiner that applies an amplified RF signal to a load. A main controller provides an automatic level control reference signal, representative of the desired output power level of each of the power amplifier modules.

Abstract: A system and method for improving the input return loss in RF amplifiers is disclosed. One embodiment of the present invention amplifies only one of the two output quadrature signals of 3 dB coupler in an amplifier module while substantially maintaining a constant impedance at the input to the 3 dB coupler. This removes one of the design constraints for designing the input network for an amplifier module thereby allowing for more flexible amplifier designs and ease of cascading amplifier modules. One embodiment of the present invention improves the input return loss of an RF amplifier pallet in a cascaded-stage power amplifier circuit for a television transmitter including a 3 dB coupler by replacing one of the two amplifiers connected to the output of the 3 dB coupler with an electrical circuit of substantially equivalent impedance to the input impedance of the non-replaced amplifier.

Abstract: A system and method for improving the input return loss in RF amplifiers is disclosed. One embodiment of the present invention amplifies only one of the two output quadrature signals of 3 dB coupler in an amplifier module while substantially maintaining a constant impedance at the input to the 3 dB coupler. This removes one of the design constraints for designing the input network for an amplifier module thereby allowing for more flexible amplifier designs and ease of cascading amplifier modules. One embodiment of the present invention improves the input return loss of an RF amplifier pallet in a cascaded-stage power amplifier circuit for a television transmitter including a 3 dB coupler by replacing one of the two amplifiers connected to the output of the 3 dB coupler with an electrical circuit of substantially equivalent impedance to the input impedance of the non-replaced amplifier.

Abstract: A power amplifier system is presented for use in amplifying an RF input signal comprising N sub-power amplifiers are connected together in parallel with each receiving and amplifying a portion of the RF input signal. A combiner combines the amplified portions of the RF input signal to provide a combined output signal. Each sub-amplifier includes at least one transistor having an input port that receives a DC bias voltage and an output port, such that when the RF input signal is not present a quiescent current flows through the output port. A controller is operative when the RF signal is not present to check and adjust the magnitude of the quiescent current flowing in each of the sub-amplifier output ports in the sequence of 1 . . . N.

Abstract: A power amplifier system is presented for amplifying an RF input signal. The system includes a vector modulator for receiving and modifying an input signal and providing therefrom a modified signal. The system also includes at least one power amplifier the operation of which is monitored and the vector modulator is controlled in accordance with the monitoring.

Abstract: An air-dielectric stripline is provided which includes top, intermediate and bottom planar dielectric layers spaced from each other in parallel planes with each layer having upper and lower oppositely directed faces. First and second electrically conductive planar ground planes are respectively attached to the lower surface of the top dielectric layer and the upper surface of the bottom dielectric layer. First and second planar dielectric spacer layers are respectively located between the top and intermediate dielectric layers and the intermediate and bottom dielectric layers for maintaining a given spacing therebetween. Each spacer layer has a channel formed therein to thereby define upper and lower air chambers on opposing faces of the intermediate layer. A conductive inner trace is attached to at least one face of the intermediate layer within one of the chambers and is spaced from an associated ground plane by the thickness of a spacer dielectric layer.