Texas Instruments Corporation

Steven Berg

Kevin Vannorsdel

John Hoversten

Carsten Barth

Vahid Yousefzadeh

Arie Van Staveren

Bert Helleman

Yushan Li

A switched mode assisted linear (SMAL) amplifier/regulator architecture can be configured to supply regulated power to a dynamic load, such as an RF power amplifier. Embodiments of a SMAL regulator can include a linear amplifier and a switched mode converter parallel coupled at a supply node, and configured such that the amplifier sets load voltage, while the amplifier and the switched converter are cooperatively controlled to supply load current. The amplifier can include separate feedback loops: an external relatively lower speed feedback loop for controlling signal path bandwidth, and an internal relatively higher speed feedback loop for controlling output impedance bandwidth of the linear amplifier. The linear amplifier can be AC coupled to the supply node, and the switched converter can be configured with a capacitive charge control loop that controls the switched converter to effectively control the amplifier to provide capacitive charge control.

Switched mode assisted linear regulator with decoupled output impedance and signal path bandwidth

The disclosed switched mode assisted linear (SMAL) amplifier/regulator architecture may be configured as a SMAL regulator to supply power to a dynamic load, such as an RF power amplifier. Embodiments of a SMAL regulator include configurations in which a linear amplifier and a switched mode converter (switcher) parallel coupled at a supply node, and configured such that the amplifier sets load voltage, while the amplifier and the switched mode converter are cooperatively controlled to supply load current. In one embodiment, the linear amplifier is AC coupled to the supply node, and the switched converter is configured with a capacitive charge control loop that controls the switched converter to effectively control the amplifier to provide capacitive charge control. In another embodiment, the amplifier includes separate feedback loops: an external relatively lower speed feedback loop may be configured for controlling signal path bandwidth, and an internal relatively higher speed feedback loop may be configured for controlling output impedance bandwidth of the linear amplifier.

Switched mode assisted linear regulator with AC coupling with capacitive charge control

A switched mode assisted linear regulator includes a linear amplifier (LA) and a buck converter configured as a current source. In example embodiments, the buck converter circuit includes a power switch Mwith an Mbody diode (tub), and includes buck turn-off circuitry configured to avoid negative inductor current by controlled switching of the tub to the higher of VIN and a second voltage. For DC-coupled configurations, boost functionality is provided by an LA boost supply, and the tub is switched to the boost supply. For AC-coupled configurations, boost functionality can be provided without boosting the LA supply rail by constraining signal peak-to-peak amplitude to be less than the LA supply voltage (maintaining a DC-average voltage on the AC-coupling capacitor), and the tub is switched to the higher of VIN and VOUT. The buck turn-off circuitry can include zero crossing detection to control Mtub switches.

Switched mode assisted linear regulator with dynamic buck turn-off using ZCD-controlled tub switching

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Littleton, CO, United States of America

Steven Berg