Abstract:
An analog-to-digital converter (ADC) has been disclosed. In some implementations, the ADC is configured to generate ADC samples based on input signals and an ADC input clock. The ADC is further configured to generate at a first time point a synchronized start signal indicating a starting point of capturing the ADC samples. The start signal and a system clock can be synchronized at a second time point. At a third time point, a capturing sample clock for capturing the ADC samples is generated. The synchronized start signal and the capturing sample clock can be input to a counter to determine a time difference between the second and third time points. An ADC output timing of the ADC samples can be determined based on the time difference.
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:
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 providing negative current information to a control loop for a buck converter in reverse boost mode. In an aspect, negative as well as positive current through an inductor is sensed and provided to adjust a ramp voltage in the control loop for the buck converter. The techniques may prevent current through the inductor during reverse boost mode from becoming increasingly negative without bound; the techniques thereby reduce settling times when the target output voltage is reduced from a first level to a second level. In an aspect, the negative current sensing may be provided by sensing negative current through a charging, or PMOS, switch of the buck converter. The sensed negative current may be subtracted from a current used to generate the ramp voltage.
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:
A delay cell for a delay locked loop, DLL, based serial link is disclosed. The delay cell has a first stage and a second stage, wherein an output of the first stage is an input to the second stage, the first stage comprising a resistive digital to analog converter, R-DAC and the second stage comprising a current starved delay cell.
Abstract:
In one embodiment, a switching regulator includes a first switching regulator stage configured between an input voltage and a first reference voltage and a second switching regulator stage configured between the first reference voltage and a second reference voltage. A first terminal of an inductor is coupled to an output of the first switching regulator stage and an output of the second switching regulator stage. The first switching regulator stage operates to produce an output voltage when the output voltage is configured above the first reference voltage, and the second switching regulator stage operates to produce an output voltage when the output voltage is configured below the first reference voltage.
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:
The present disclosure includes envelope tracking circuits and methods with adaptive switching frequency. In one embodiment, a circuit comprising an amplifier to receive an envelope tracking signal having an envelope tracking frequency and output voltage and current to a power supply terminal of a power amplifier circuit. A programmable comparator receives an output signal from the amplifier and generates a switching signal having a switching frequency. A switching regulator stage receives the switching signal and outputs a switching current to the power supply terminal. A frequency comparison circuit configures the programmable comparator based on the envelope tracking frequency and the switching frequency so that the switching frequency tracks the envelope tracking frequency.
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.