A superposition operation circuit and a float-voltage digital-to-analog conversion circuit to superpose analog elements according to an indirect current superposition principle, where a voltage follower is implemented using a first operational amplifier such that an output end of the voltage follower is clamped to a voltage that is input to a positive-phase input end, namely, a to-be-superposed analog element. Then a current generation circuit converts a voltage signal to a current signal, a voltage drop for the current signal is generated on a first resistor coupled to an output end of the first operational amplifier, and the voltage drop is superposed on a voltage signal output by the first operational amplifier.

Systems, methods, and circuitries are provided for generating a power amplifier supply voltage based on a target envelope signal for a radio frequency (RF) transmit signal. An envelope tracking system includes a first selector circuitry and predistortion circuitry. The first selector circuitry is disposed in a selector module and is configured to input a plurality of voltages conducted on a first plurality of power lanes, wherein the first plurality of power lanes is part of a power distribution network; select a voltage from the plurality of voltages based on the target envelope signal; and provide the selected voltage to a supply lane connected to an input of the power amplifier that amplifies the RF transmit signal. The predistortion circuitry is configured to modify the RF transmit signal based on a selected power lane of the first plurality of power lanes that conducts the selected voltage.

Systems, methods, and circuitries are provided for generating a power amplifier supply voltage based on a target envelope signal for a radio frequency (RF) transmit signal. An envelope tracking system includes a first selector circuitry and predistortion circuitry. The first selector circuitry is disposed in a selector module and is configured to input a plurality of voltages conducted on a first plurality of power lanes, wherein the first plurality of power lanes is part of a power distribution network; select a voltage from the plurality of voltages based on the target envelope signal; and provide the selected voltage to a supply lane connected to an input of the power amplifier that amplifies the RF transmit signal. The predistortion circuitry is configured to modify the RF transmit signal based on a selected power lane of the first plurality of power lanes that conducts the selected voltage.

An adapter (10) and a charging control method, the adapter (10) comprising: a power conversion unit (11), used for converting an inputted alternating current so as to obtain an output voltage and an output current of the adapter (10), the output current of the adapter (10) being an alternating current or a pulsed direct current; a voltage holding unit (12), an input end of the voltage holding unit (12) being connected to the power conversion unit (11), the voltage holding unit (12) being used for obtaining an input voltage having a pulsed waveform from the power conversion unit (11) and converting the input voltage having the pulsed waveform into a target voltage, an output end of the voltage holding unit (12) being connected to a device in the adapter (10), the target voltage being used to power the device in the adapter (10), a peak value of the target voltage being between the lowest operating voltage and the highest operating voltage of the device. The adapter (10) reduces lithium separation in batteries, and increases the service life of batteries.

A system may include a charge pump configured to operate in a plurality of modes including a first mode in which the ratio of an output voltage to an input voltage of the charge pump is a first ratio and a second mode in which the ratio is a second ratio and a controller configured to limit current flowing between a power source of the charge pump to the charge pump, wherein the power source provides the input voltage, by limiting a transfer of charge between the power source and the charge pump during a switching cycle of the charge pump responsive to a change in operation between modes of the plurality of modes.

In described examples, a quadrature phase shifter includes digitally programmable phase shifter networks for generating leading and lagging output signals in quadrature. The phase shifter networks include passive components for reactively inducing phase shifts, which need not consume active power. Output currents from the transistors coupled to the phase shifter networks are substantially in quadrature and can be made further accurate by adjusted by a weight function implemented using current steering elements. Example low-loss quadrature phase shifters described herein can be functionally integrated to provide low-power, low-noise up/down mixers, vector modulators and transceiver front-ends for millimeter wavelength (mmwave) communication systems.

Apparatus and associated methods relating to a digital-to-analog converter (DAC) include a programmable resistance network coupled between a voltage supply node V.sub.DD and a switch cell circuit to provide a predetermined resistance in response to the V.sub.DD and current I.sub.S of the switch cell circuit. In an illustrative example, the DAC may include a switch cell circuit comprising one or more switch cells connected in parallel. Each switch cell may include a differential gain circuit having a first branch coupled to a second branch at an input of a current source. The programmable resistance may include a variable resistance configured to adjust a voltage (Vbias) supplied to the switch cell circuit in response to a control signal. By introducing the programmable resistance network, predetermined bias and/or gain values may be dynamically adjusted with a constant board-level power supply V.sub.DD.

Apparatus and associated methods relating to a digital-to-analog converter (DAC) include a programmable resistance network coupled between a voltage supply node V.sub.DD and a switch cell circuit to provide a predetermined resistance in response to the V.sub.DD and current I.sub.S of the switch cell circuit. In an illustrative example, the DAC may include a switch cell circuit comprising one or more switch cells connected in parallel. Each switch cell may include a differential gain circuit having a first branch coupled to a second branch at an input of a current source. The programmable resistance may include a variable resistance configured to adjust a voltage (Vbias) supplied to the switch cell circuit in response to a control signal. By introducing the programmable resistance network, predetermined bias and/or gain values may be dynamically adjusted with a constant board-level power supply V.sub.DD.

A method and apparatus for measuring phase response in a radio receiver is disclosed. A radio receiver includes a digital-to-analog (D/A) conversion unit coupled to receive a test signal. The D/A conversion unit includes a number of single-bit digital-to-analog conversion (DAC) circuits coupled to receive the test signal and configured to convert it into the analog domain. Clock signals received by each of the single-bit DAC circuits are out of phase with respect to one another. The output of the D/A conversion unit is an analog signal that is a composite of the signals output by the DAC circuits therein. The analog signal is then conveyed to an analog-to-digital converter (ADC) and converted into an N-bit digital signal. The N-bit digital signal is then conveyed to a correlator to determine a phase response of the radio receiver.

A method and apparatus for measuring phase response in a radio receiver is disclosed. A radio receiver includes a digital-to-analog (D/A) conversion unit coupled to receive a test signal. The D/A conversion unit includes a number of single-bit digital-to-analog conversion (DAC) circuits coupled to receive the test signal and configured to convert it into the analog domain. Clock signals received by each of the single-bit DAC circuits are out of phase with respect to one another. The output of the D/A conversion unit is an analog signal that is a composite of the signals output by the DAC circuits therein. The analog signal is then conveyed to an analog-to-digital converter (ADC) and converted into an N-bit digital signal. The N-bit digital signal is then conveyed to a correlator to determine a phase response of the radio receiver.