Abstract: Techniques for dynamically generating a headroom voltage for an envelope tracking system. In an aspect, an initial headroom voltage is updated when a signal from a power amplifier (PA) indicates that the PA headroom is insufficient. The initial headroom voltage may be updated to an operating headroom voltage that includes the initial voltage plus a deficiency voltage plus a margin. In this manner, the operating headroom voltage may be dynamically selected to minimize power consumption while still ensuring that the PA is linear. In a further aspect, a specific exemplary embodiment of a headroom voltage generator using a counter is described.

Abstract: Techniques for generating a boost clock signal for a boost converter from a buck converter clock signal, wherein the boost clock signal has a limited frequency range. In an aspect, the boost clock signal has a maximum frequency determined by Vbst/T, wherein Vbst represents the difference between a target output voltage and a battery voltage, and T represents a predetermined cycle duration. The boost converter may include a pulse insertion block to limit the minimum frequency of the boost clock signal, and a dynamic blanking/delay block to limit the maximum frequency of the boost clock signal. Further techniques are disclosed for generally implementing the minimum frequency limiting and maximum frequency limiting blocks.

Abstract: Techniques for preventing reverse current in applications wherein a tracking supply voltage is placed in parallel with a switching power stage. The tracking supply voltage may be boosted to a level higher than a battery supply voltage using, e.g., a boost converter. In an aspect, a negative current detection block is provided to detect negative current flow from the boosted tracking supply voltage to the battery supply voltage. A high-side switch of the switching power stage may be disabled in response to detecting the negative current. To prevent false tripping, the tracking supply voltage may be further compared with the battery supply voltage, and a latch may be provided to further control the high-side switch.

Abstract: Simple and efficient techniques for closed loop control of a boost converter. In an aspect, a current feed-forward (CFF) mode of operation includes providing current information to a control logic block controlling transistor switches of the boost converter to advantageously smooth the signals present in the closed loop control of the system. In another aspect, a modified peak current (MPC) mode of operation includes providing a simplified control mechanism based on a peak current mode of operation. Both CFF mode and MPC mode may share similar circuit elements, allowing a single implementation to selectively implement either of these modes of control. Further techniques are provided for determining average current information for the logic block.

Abstract: Techniques for reducing ringing arising from L-C coupling in a boost converter circuit during a transition from a boost ON state to a boost OFF state. In an aspect, during an OFF state of the boost converter circuit, the size of the high-side switch coupling a boost inductor to the load is gradually increased over time. In this manner, the on-resistance of the high-side switch is decreased from a first value to a second (lower) value over time, which advantageously reduces ringing (due to high quality factor or Q) when initially entering the OFF state, while maintaining low conduction losses during the remainder of the OFF state. Further techniques are provided for implementing the high-side switch as a plurality of parallel-coupled transistors.

Abstract: Techniques for creating one or more notch frequencies in the power density spectrum of an output voltage generated by switching circuitry. In an aspect, high- and low-side switches are coupled to an output voltage via an inductor. The spectral power of the output voltage at one or more frequencies is estimated, and the estimated spectral power is provided to a switch controller controlling the switches. The switch controller may be configured to switch the switches only in response to detecting that the estimated spectral power at the notch frequency is at a minimum. In certain exemplary aspects, the techniques may be incorporated in an envelope-tracking system, wherein the switching circuitry forms part of a switched-mode power supply (SMPS) supplying low-frequency power to a power amplifier load.

Abstract: In a particular embodiment, an apparatus includes an electrostatic discharge (ESD) clamping transistor coupled to a ground terminal of a device. The apparatus further includes a switch coupled between a body terminal of the ESD clamping transistor and the around terminal.

Abstract: Techniques for dynamically generating a headroom voltage for an envelope tracking system. In an aspect, an initial headroom voltage is updated when a signal from a power amplifier (PA) indicates that the PA headroom is insufficient. The initial headroom voltage may be updated to an operating headroom voltage that includes the initial voltage plus a deficiency voltage plus a margin. In this manner, the operating headroom voltage may be dynamically selected to minimize power consumption while still ensuring that the PA is linear. In a further aspect, a specific exemplary embodiment of a headroom voltage generator using a counter is described.

Abstract: Techniques for dynamically generating a headroom voltage for an envelope tracking system. In an aspect, an initial headroom voltage is updated when a signal from a power amplifier (PA) indicates that the PA headroom is insufficient. The initial headroom voltage may be updated to an operating headroom voltage that includes the initial voltage plus a deficiency voltage plus a margin. In this manner, the operating headroom voltage may be dynamically selected to minimize power consumption while still ensuring that the PA is linear. In a further aspect, a specific exemplary embodiment of a headroom voltage generator using a counter is described.

Abstract: Techniques for reducing ringing arising from L-C coupling in a boost converter circuit during a transition from a boost ON state to a boost OFF state. In an aspect, during an OFF state of the boost converter circuit, the size of the high-side switch coupling a boost inductor to the load is gradually increased over time. In this manner, the on-resistance of the high-side switch is decreased from a first value to a second (lower) value over time, which advantageously reduces ringing (due to high quality factor or Q) when initially entering the OFF state, while maintaining low conduction losses during the remainder of the OFF state. Further techniques are provided for implementing the high-side switch as a plurality of parallel-coupled transistors.

Abstract: Techniques for dynamically generating a headroom voltage for an envelope tracking system. In an aspect, an initial headroom voltage is updated when a signal from a power amplifier (PA) indicates that the PA headroom is insufficient. The initial headroom voltage may be updated to an operating headroom voltage that includes the initial voltage plus a deficiency voltage plus a margin. In this manner, the operating headroom voltage may be dynamically selected to minimize power consumption while still ensuring that the PA is linear. In a further aspect, a specific exemplary embodiment of a headroom voltage generator using a counter is described.

Abstract: Techniques for preventing reverse current in applications wherein a tracking supply voltage is placed in parallel with a switching power stage. The tracking supply voltage may be boosted to a level higher than a battery supply voltage using, e.g., a boost converter. In an aspect, a negative current detection block is provided to detect negative current flow from the boosted tracking supply voltage to the battery supply voltage. A high-side switch of the switching power stage may be disabled in response to detecting the negative current. To prevent false tripping, the tracking supply voltage may be further compared with the battery supply voltage, and a latch may be provided to further control the high-side switch.

Abstract: Techniques for creating one or more notch frequencies in the power density spectrum of an output voltage generated by switching circuitry. In an aspect, high- and low-side switches are coupled to an output voltage via an inductor. The spectral power of the output voltage at one or more frequencies is estimated, and the estimated spectral power is provided to a switch controller controlling the switches. The switch controller may be configured to switch the switches only in response to detecting that the estimated spectral power at the notch frequency is at a minimum. In certain exemplary aspects, the techniques may be incorporated in an envelope-tracking system, wherein the switching circuitry forms part of a switched-mode power supply (SMPS) supplying low-frequency power to a power amplifier load.

Abstract: In a particular embodiment, an apparatus includes an electrostatic discharge (ESD) clamping transistor coupled to a ground terminal of a device. The apparatus further includes a switch coupled between a body terminal of the ESD clamping transistor and the around terminal.

Abstract: Techniques for generating a boost clock signal for a boost converter from a buck converter clock signal, wherein the boost clock signal has a limited frequency range. In an aspect, the boost clock signal has a maximum frequency determined by Vbst/T, wherein Vbst represents the difference between a target output voltage and a battery voltage, and T represents a predetermined cycle duration. The boost converter may include a pulse insertion block to limit the minimum frequency of the boost clock signal, and a dynamic blanking/delay block to limit the maximum frequency of the boost clock signal. Further techniques are disclosed for generally implementing the minimum frequency limiting and maximum frequency limiting blocks.

Abstract: Techniques for controlling boost converter operation in an envelope tracking (ET) system. In an aspect, an enable generation block is provided to generate an enable signal for a boost converter, wherein the enable signal is turned on in response to detecting that a sum of a first headroom voltage and an enable peak of a tracking supply voltage is greater than an amplifier supply voltage of the ET system. The enable signal may be turned on for a predetermined enable on duration. In another aspect, a target generation block is provided to generate a target voltage for the boost converter, wherein the target voltage comprises the sum of a second headroom voltage and a target peak of the tracking supply voltage.