Abstract: A balun signal splitter for use in transceiver systems, such as wireless communications systems, including a wide-band balun with a secondary winding for signal splitting between two operating bands (e.g., high-band and low-band) or modes. An example of a balun signal splitter configured for dual-band or dual-mode operation or includes a balun having a primary winding and a secondary winding, the secondary winding having a first port and a second port, a first network coupled to the first port and configured to present a short circuit impedance at the first port at out-of-band frequencies or during out-of-mode operation, and a second network coupled to the second port and configured to present a short circuit impedance at the second port at out-of-band frequencies or during out-of-mode operation.

Abstract: An electronic module with an integrated electromagnetic shield using surface mount shield wall components has been disclosed. Each surface mount shield wall component provides side shielding of the circuitry within the overmolded electronic module and provides an exposed conductive shield wall section to which a top conductive shield can be applied. By including the shield structure as part of the overmolded electronic module, the need for a separate shield and separate process steps for installing the separate shield can be eliminated. Each surface mount shield wall component comprises a non-conductive portion that provides stability during a reflow soldering process, but at least a sacrificial portion of the non-conductive portion can be removed to reduce the amount of area occupied by the overmoldable shield structure.

Abstract: A method for making an electronic module with an integrated electromagnetic shield uses surface mount shield wall components. At least one electronic component and two or more of the shield wall components are mounted on a surface of a circuit board panel using a pick-and-place process. Each shield wall component has a conductive portion and a non-conductive portion mounted in contact with the surface of the circuit board panel. The mounted shield wall components form a conductive wall to electromagnetically shield the electronic component. The non-conductive portion of one or more of the mounted shield wall components is sawn through, leaving some or all of the conductive portion of the mounted shield wall components. A top conductive shield can be applied. The non-conductive portions can provide stability during a reflow soldering process, while the sacrificial non-conductive portions are sawn through so that they can be removed to reduce the amount of area occupied by the overmoldable shield structure.

Abstract: A balun signal splitter for use in transceiver systems, such as wireless communications systems, including a wide-band balun with a secondary winding for signal splitting between two operating bands (e.g., high-band and low-band) or modes. An example of a balun signal splitter configured for dual-band or dual-mode operation or includes a balun having a primary winding and a secondary winding, the secondary winding having a first port and a second port, a first network coupled to the first port and configured to present a short circuit impedance at the first port at out-of-band frequencies or during out-of-mode operation, and a second network coupled to the second port and configured to present a short circuit impedance at the second port at out-of-band frequencies or during out-of-mode operation.

Abstract: In a portable radio transceiver, a power amplifier system includes a load line switch that operates in response to a mode control signal to promote high efficiency in both a high-power mode and a low-power mode. The switching circuit is operable to couple the inductance to the shunt capacitance in response to a control signal indicating operation in a low-power mode. The switching circuit is further operable to decouple the inductance from the shunt capacitance in response to a control signal indicating operation in a high-power mode. In the low-power mode, the inductance couples with the shunt capacitance to decrease total capacitance at the output of the power amplifier. In the high-power mode, the total capacitance at the output of the power amplifier is substantially equal to the shunt capacitance alone, and the inductance essentially has no effect on total capacitance at the power amplifier output.

Abstract: An electronic module with an integrated electromagnetic shield using surface mount shield wall components has been disclosed. Each surface mount shield wall component provides side shielding of the circuitry within the overmolded electronic module and provides an exposed conductive shield wall section to which a top conductive shield can be applied. By including the shield structure as part of the overmolded electronic module, the need for a separate shield and separate process steps for installing the separate shield can be eliminated. Each surface mount shield wall component comprises a non-conductive portion that provides stability during a reflow soldering process, but at least a sacrificial portion of the non-conductive portion can be removed to reduce the amount of area occupied by the overmoldable shield structure.

Abstract: An electronic module with an integrated electromagnetic shield using surface mount shield wall components has been disclosed. Each surface mount shield wall component provides side shielding of circuitry within the overmolded electronic module and provides an exposed conductive shield wall section to which a top conductive shield can be applied. By including the shield structure as part of the overmolded electronic module, the need for a separate shield and separate process steps for installing the separate shield can be eliminated. Each surface mount shield wall component comprises a non-conductive portion that provides stability during a reflow soldering process, but at least a sacrificial portion of the non-conductive portion can be removed to reduce the amount of area occupied by the overmoldable shield structure.

Abstract: An exemplary antenna switching circuit comprises first, second, third and fourth switches. The first switch is activated by a first control signal for establishing a connection between a first transmit port and an antenna; the second switch is activated by a second control signal for establishing a connection between a second transmit port and the antenna; the third switch is activated by a third control signal for establishing a connection between a first receive port and the antenna; and the fourth switch is activated by the third control signal for establishing a connection between a second receive port and the antenna. With this arrangement, the first receive port and the second receive port are simultaneously connected to the antenna when the third switch and the fourth switch are activated by the third control signal.

Abstract: The invention includes a Doherty power amplifier system having a Doherty power amplifier electrically connected to a Doherty bias circuit. The Doherty amplifier includes a carrier amplifier and peaking amplifier. The Doherty bias circuit includes a current mirror and a first node that works to maintain a constant current in the current mirror as a function of a base voltage at the first node. The base voltage that results in a constant current is passed from a current mirror circuit to the carrier amplifier. The base voltage is at least one of scaled and shifted to produce a second voltage at a second node by employing a scaling/level shifting circuit. The scaling/level shifting circuit includes an input electronically connected to the current mirror circuit. The second voltage is passed through a voltage buffer to the peaking amplifier. An effect of the invention is to generate bias voltages for a Doherty amplifier that dynamically adjust to compensate for manufacturing process and environmental changes.

Abstract: According to an exemplary embodiment, a circuit arrangement includes a multi-mode bias circuit having a control voltage input, a mode control input for selecting between a linear mode and a saturation mode, and a bias output. The circuit arrangement further includes an amplifier having a bias input connected to the bias output of the multi-mode bias circuit, the amplifier having an RF input and an RF output. The multi-mode bias circuit causes the amplifier RF output power to be proportional to the RF input power when the mode control input selects the linear mode. Conversely, the multi-mode bias circuit causes the amplifier RF output power to be determined by the voltage at the control voltage input when the mode control input selects the saturation mode.

Abstract: The invention includes a Doherty power amplifier system having a Doherty power amplifier electrically connected to a Doherty bias circuit. The Doherty amplifier includes a carrier amplifier and peaking amplifier. The Doherty bias circuit includes a current mirror and a first node that works to maintain a constant current in the current mirror as a function of a base voltage at the first node. The base voltage that results in a constant current is passed from a current mirror circuit to the carrier amplifier. The base voltage is at least one of scaled and shifted to produce a second voltage at a second node by employing a scaling/level shifting circuit. The scaling/level shifting circuit includes an input electronically connected to the current mirror circuit. The second voltage is passed through a voltage buffer to the peaking amplifier. An effect of the invention is to generate bias voltages for a Doherty amplifier that dynamically adjust to compensate for manufacturing process and environmental changes.

Abstract: A Doherty amplifier system including a quarter wave transformer/combiner circuit which may be implemented as a low cost radio frequency integrated circuit, thereby absorbing and minimizing the effects of parasitics such as bond wires and stray capacitance. The quarter wave transformer/combiner circuit may be a lumped pi network configured as an integral number of sections coupled in parallel, with each such section comprising a series combination of a shunt inductance, series capacitance, and shunt inductance. The circuit may also provide bias voltage to the carrier and peaking amplifiers and/or maintain DC isolation therebetween. The circuit may also decrease the load impedance presented to the carrier amplifier as input power increases, thus allowing the efficiency of the system to be kept relatively constant over a prescribed power range.

Abstract: The invention includes a Doherty power amplifier system having a Doherty power amplifier electrically connected to a Doherty bias circuit. The Doherty amplifier includes a carrier amplifier and peaking amplifier. The Doherty bias circuit includes a current mirror and a first node that works to maintain a constant current in the current mirror as a function of a base voltage at the first node. The base voltage that results in a constant current is passed from a current mirror circuit to the carrier amplifier. The base voltage is at least one of scaled and shifted to produce a second voltage at a second node by employing a scaling/level shifting circuit. The scaling/level shifting circuit includes an input electronically connected to the current mirror circuit. The second voltage is passed through a voltage buffer to the peaking amplifier. An effect of the invention is to generate bias voltages for a Doherty amplifier that dynamically adjust to compensate for manufacturing process and environmental changes.

Abstract: An intermediate frequency amplifier for wireless communication applications has the same receive path and transmit path through an off-chip filter. The intermediate frequency amplifier circuit includes a first amplifier and a second amplifier. The second amplifier includes a gain control circuitry. The second amplifier provides gain control for both the receive mode and for the transmit mode of operation. The IF amplifier can be used in a variety of communication applications, including cordless telephones, cellular phones, PHS phones, wireless modems, radios, and other devices.

Abstract: The invention includes an amplifier and a biasing circuit. The amplifier may have one or more driver stages and a final stage. Each stage may be connected in series to pass along and amplify an input signal from one stage to the next. The input signal level may increase over time. The biasing circuit may include a voltage follower having an output and a reference transistor. Each stage may include a transistor having a base that is connected to the output of the voltage follower. A resistor may be placed between each transistor stage base and the output of the voltage follower. The base of the final stage transistor may be DC connected to the reference transistor base. In operation, the reference transistor collector current and thus the final stage base bias voltage may be maintained at fixed level by feedback through the voltage follower.

Abstract: A Doherty amplifier system including a quarter wave transformer/combiner circuit which may be implemented as a low cost radio frequency integrated circuit, thereby absorbing and minimizing the effects of parasitics such as bond wires and stray capacitance. The quarter wave transformer/combiner circuit may be a lumped pi network configured as an integral number of sections coupled in parallel, with each such section comprising a series combination of a shunt inductance, series capacitance, and shunt inductance. The circuit may also provide bias voltage to the carrier and peaking amplifiers and/or maintain DC isolation therebetween. The circuit may also decrease the load impedance presented to the carrier amplifier as input power increases, thus allowing the efficiency of the system to be kept relatively constant over a prescribed power range.

Abstract: A frequency conversion or synthesis circuit including a double balance differential active ring mixer with a current shared active radio frequency (RF) input balun, suitable for use in an RF receiver. The circuit is configured to be coupled to a bias circuit for providing a relatively constant current and a buffer circuit for receiving a signal from a local oscillator (LO) source and generating differential LO signals.

Abstract: An electronically controlled oscillator capable of operating in the rf/microwave frequency range, and using a stacked crystal filter as the frequency determining element in the oscillator. A non-linear element including an appropriately biased high frequency amplifier has the stacked crystal filter connected in its feedback path and provides a loop gain of greater than 1 to meet one aspect of the Barkhausen criteria. An electronically variable impedance, such as a hyperabrupt junction varactor, is connected in the feedback loop along with the stacked crystal filter to controllably insert a phase adjustment into the feedback path, to be compensated by a phase adjustment by the stacked crystal filter, thereby to controllably maintain a loop phase shift which is an integral number of 2.pi. radians at the oscillator frequency, and to vary the oscillator output frequency about the frequency of the stacked crystal filter in a controllable fashion.