Abstract: An integrated circuit includes a radio frequency (RF) amplifier having a trifilar transformer coupled to a gain device in two negative feedback paths. The trifilar transformer includes a first winding, a second winding and a third winding, a first dielectric core is disposed between the first winding and the second winding, and a second dielectric core is disposed between the second winding and the third winding. A first winding ratio between the first winding and the second winding combined with a second winding ratio between the second winding and the third winding affects a total gain of the RF amplifier. In a specific embodiment, the gain device is a transistor, the first winding is coupled to a base of the transistor, the second winding is coupled to a collector of the transistor, and the third winding is coupled to an emitter of the transistor.

Abstract: An asymmetrical transformer output demultiplexing (ATODEM) circuit is disclosed. The ATODEM circuit of the present disclosure includes N input windings, wherein N is a natural number. Each of the N input windings have input terminals that couple to output terminals of N PAs. The ATODEM further includes M output ports wherein M is a natural number, each of the M output ports having N series coupled windings coupled between a load terminal and a return terminal. The physical attributes of the N input windings, and the N series coupled windings of the M output ports are asymmetrical such that in an Nth operation mode an Nth PA first-load line impedance matches an output impedance of an Nth PA coupled to the input terminals.

Abstract: A SPDT or SPMT switch may include a transformer having a primary winding and a secondary winding, where a first end of the secondary winding is connected to a single pole port, where a first end of the primary winding is connected to a first throw port; a first switch having a first end and a second end, where the first end is connected to ground; and a second switch, where a second end of the secondary winding is connected to both a second end of the first switch and a first end of the second switch, where a second end of the second switch is connected to a second throw port, where the first switch controls a first communication path between the single pole port and the first throw port, and where the second switch controls a second communication path between the second throw port and the single pole port.

Abstract: A power amplifier includes a transistor, a transmission line transformer, and a capacitor. The transistor is operable to receive a signal and to generate an amplified signal. The transistor has a source, a drain, and a gate. The gate has a first impedance and is operable to receive the signal to be amplified. The transmission line transformer has a first, second, third, and fourth port, the first port and the third port being coupled directly to the gate of the transistor, and the fourth port being coupled to a source device having a second impedance. The capacitor has a first end and a second end. The first end of the capacitor is coupled to the second port of the transmission line transformer and the second end is coupled to a ground.

Abstract: A power amplifier includes a transistor, a transmission line transformer, and a capacitor. The transistor is operable to receive a signal and to generate an amplified signal. The transistor has a source, a drain, and a gate. The gate has a first impedance and is operable to receive the signal to be amplified. The transmission line transformer has a first, second, third, and fourth port, the first port being coupled to the gate of the transistor and the third port, and the fourth port being coupled to a source device having a second impedance. The capacitor has a first end and a second end. The first end of the capacitor is coupled to the second port of the transmission line transformer and the second end is coupled to a ground.

Abstract: Reconfigurable distributed active transformers are provided. The exemplary embodiments provided allow changing of the effective number and configuration of the primary and secondary windings, where the distributed active transformer structures can be reconfigured dynamically to control the output power levels, allow operation at multiple frequency bands, maintain a high performance across multiple channels, and sustain desired characteristics across process, temperature and other environmental variations. Integration of the distributed active transformer power amplifiers and a low noise amplifier on a semiconductor substrate can also be provided.

Abstract: A system and method for employing variable magnetic flux bias in an amplifier. The amplifier system comprises an output transformer and a magnetic sensor configured to sense a first magnetic flux of the output transformer. The magnetic sensor generates a flux signal responsive to the first magnetic flux. Control circuitry is configured to receive the flux signal and to generate a control signal responsive to the flux signal. A winding is configured to receive the control signal and to induce a second magnetic flux within the output transformer responsive to the control signal, the second magnetic flux having opposite polarity to the first magnetic flux. The second magnetic flux may maintain a non-zero quiescent magnetic bias level within the output transformer, or may substantially cancel or null the DC and low-frequency subsonic components of the first magnetic flux.

Abstract: An integrated RF power amplifier 20 includes an on-chip input transformer (24) and an on-chip output transformer (28). Each of the transformers (24, 28) is formed from four spirals. Each primary winding (34, 42) and each secondary winding (38, 44) includes positive and negative spirals arranged so that positive current rotates in opposing rotational directions in the positive and negative spirals. The secondary winding (38) of the input transformer (24) and the primary winding (42) of the output transformer (28) each has a center tap (48, 50) located at the electrical and physical center of the winding. Positive and negative amplifiers (26) couple between the secondary winding of the input transformer (24) and the primary winding of the output transformer (28). DC biasing for the amplifiers (26) is provided through the positive and negative spirals of the center-tapped windings (38, 42) from the respective center taps (48, 50).

Abstract: An ohmically isolating input circuit accepts a three pin connector of a cable from a signal source output for virtually all three pin connector standards, and will output a signal of the same voltage regardless of which of the three pin connector standards are used. In one embodiment of the invention, the input circuit includes a center tapped transformer having its tap primary winding side connected to the circuits three input terminals and having its secondary winding side connected directly into the input of an operational amplifier which forces the transformer to operate as a current transformer with virtually no voltage drop across its secondary or primary windings. The output of the operational amplifier, which serves as the output of the input circuit, is fed back to the inverting input of the operational amplifier to provide a high gain negative feedback circuit which converts signal currents from the transformer secondary winding to an output voltage signal.

Abstract: An ohmically isolated input circuit accepts a three pin connector of a cable from a signal source output for virtually all three pin connector standards, and will output a signal of the same voltage gain regardless of which of the three pin connector standards are used. The input circuit includes two magnetically isolated, serially connected transformers and three input terminals connected to the transformer's serially connected primary windings so that the input signal to any two of the three terminals is transformer coupled without change in gain to the circuit output through one or the other or both of the transformers depending on which two input terminals are selected. By using current transformers rather than voltage transformers the transformers run at very low signal levels thereby permitting the use of inexpensive and lightweight transformers without the introduction of distortion.

Abstract: A picture reproducing apparatus for a helical scanning video tape recorder including an impedance transformer; a video head connected to the input of the impedance transformer; a resonance circuit connected to the output of the impedance transformer; a pre-amplifier connected to the output of the resonance circuit; a feedback resistor connected between the junction of the pre-amplifier and resonance circuit and the output of the pre-amplifier; and an output terminal connected to the output of the pre-amplifier. The impedance transformer has the output impedance four times as high as the input impedance thereof.

Abstract: A low frequency transformer for an audio system has a core, a primary winding, a secondary winding, insulation between the primary and secondary windings, a tertiary winding, and insulation between the secondary and tertiary windings. One end of the tertiary winding is embedded in the insulation between the secondary and tertiary windings, and the other end is grounded. With a tertiary winding arranged and connected in this fashion, the effects of external interference signals are substantially eliminated, and the output of the transformer is improved, i.e., it has less waveshape and frequency distortion. Preferably, the primary and tertiary windings are wound around the core in the same direction while the secondary winding is wound around the core in the opposite direction.