Abstract: Front end systems with switched termination for enhanced intermodulation distortion performance are provided herein. The switched termination can be used on transmit paths and/or receive paths of the front end system to suppress impedance variation when the signal paths are inactive. For example, with respect to switched termination for transmit paths, a front end system can include a frequency multiplexing circuit connected to a band switch by a first radio frequency (RF) signal path and by a second RF signal path. The band switch selectively provides the frequency multiplexing circuit with a first transmit signal over the first RF signal path and with a second transmit signal over the second RF signal path. The front end system further includes a switched termination circuit in shunt with the first RF signal path and operable to turn on to suppress impedance variation when the first RF signal path is inactive.

Abstract: Front end systems with switched termination for enhanced intermodulation distortion performance are provided herein. The switched termination can be used on transmit paths and/or receive paths of the front end system to suppress impedance variation when the signal paths are inactive. For example, with respect to switched termination for transmit paths, a front end system can include a frequency multiplexing circuit connected to a band switch by a first radio frequency (RF) signal path and by a second RF signal path. The band switch selectively provides the frequency multiplexing circuit with a first transmit signal over the first RF signal path and with a second transmit signal over the second RF signal path. The front end system further includes a switched termination circuit in shunt with the first RF signal path and operable to turn on to suppress impedance variation when the first RF signal path is inactive.

Abstract: Front end systems with switched termination for enhanced intermodulation distortion performance are provided herein. The switched termination can be used on transmit paths and/or receive paths of the front end system to suppress impedance variation when the signal paths are inactive. For example, with respect to switched termination for transmit paths, a front end system can include a frequency multiplexing circuit connected to a band switch by a first radio frequency (RF) signal path and by a second RF signal path. The band switch selectively provides the frequency multiplexing circuit with a first transmit signal over the first RF signal path and with a second transmit signal over the second RF signal path. The front end system further includes a switched termination circuit in shunt with the first RF signal path and operable to turn on to suppress impedance variation when the first RF signal path is inactive.

Abstract: Front end systems with switched termination for enhanced intermodulation distortion performance are provided herein. The switched termination can be used on transmit paths and/or receive paths of the front end system to suppress impedance variation when the signal paths are inactive. For example, with respect to switched termination for transmit paths, a front end system can include a frequency multiplexing circuit connected to a band switch by a first radio frequency (RF) signal path and by a second RF signal path. The band switch selectively provides the frequency multiplexing circuit with a first transmit signal over the first RF signal path and with a second transmit signal over the second RF signal path. The front end system further includes a switched termination circuit in shunt with the first RF signal path and operable to turn on to suppress impedance variation when the first RF signal path is inactive.

Abstract: Front end systems with switched termination for enhanced intermodulation distortion performance are provided herein. The switched termination can be used on transmit paths and/or receive paths of the front end system to suppress impedance variation when the signal paths are inactive. For example, with respect to switched termination for transmit paths, a front end system can include a frequency multiplexing circuit connected to a band switch by a first radio frequency (RF) signal path and by a second RF signal path. The band switch selectively provides the frequency multiplexing circuit with a first transmit signal over the first RF signal path and with a second transmit signal over the second RF signal path. The front end system further includes a switched termination circuit in shunt with the first RF signal path and operable to turn on to suppress impedance variation when the first RF signal path is inactive.

Abstract: Apparatus and methods for multi-mode charge pumps are disclosed herein. In certain configurations, a multi-mode charge pump includes an output terminal, a mode control circuit that operates the multi-mode charge pump in a selected mode, a first switched capacitor, a capacitor charging circuit, and a plurality of switches. The capacitor charging circuit connects a first end of the first switched capacitor to a charging voltage in a first phase of a clock signal, and connects the first end of the first switched capacitor to a reference voltage in a second phase of the clock signal. The charging voltage has a voltage level that changes based on the selected mode. The plurality of switches connect a second end of the first switched capacitor to the reference voltage in the first phase, and connect the second end of the first switched capacitor to the output terminal in the second phase.

Abstract: Apparatus and methods for multi-mode charge pumps are disclosed herein. In certain configurations, a multi-mode charge pump includes an output terminal, a mode control circuit that operates the multi-mode charge pump in a selected mode, a first switched capacitor, a capacitor charging circuit, and a plurality of switches. The capacitor charging circuit connects a first end of the first switched capacitor to a charging voltage in a first phase of a clock signal, and connects the first end of the first switched capacitor to a reference voltage in a second phase of the clock signal. The charging voltage has a voltage level that changes based on the selected mode. The plurality of switches connect a second end of the first switched capacitor to the reference voltage in the first phase, and connect the second end of the first switched capacitor to the output terminal in the second phase.

Abstract: A switch control circuit includes a positive voltage bias node, a voltage-regulated positive supply rail coupled to the positive voltage bias node, a charge pump coupled to a charge pump supply node, and a current source positive supply rail coupled to the charge pump supply node and configured to supply the charge pump.

Abstract: Apparatus and methods for multi-mode charge pumps are disclosed herein. In certain configurations, a multi-mode charge pump includes an output terminal, a mode control circuit that operates the multi-mode charge pump in a selected mode, a first switched capacitor, a capacitor charging circuit, and a plurality of switches. The capacitor charging circuit connects a first end of the first switched capacitor to a charging voltage in a first phase of a clock signal, and connects the first end of the first switched capacitor to a reference voltage in a second phase of the clock signal. The charging voltage has a voltage level that changes based on the selected mode. The plurality of switches connect a second end of the first switched capacitor to the reference voltage in the first phase, and connect the second end of the first switched capacitor to the output terminal in the second phase.

Abstract: Front end systems with switched termination for enhanced intermodulation distortion performance are provided herein. The switched termination can be used on transmit paths and/or receive paths of the front end system to suppress impedance variation when the signal paths are inactive. For example, with respect to switched termination for transmit paths, a front end system can include a frequency multiplexing circuit connected to a band switch by a first radio frequency (RF) signal path and by a second RF signal path. The band switch selectively provides the frequency multiplexing circuit with a first transmit signal over the first RF signal path and with a second transmit signal over the second RF signal path. The front end system further includes a switched termination circuit in shunt with the first RF signal path and operable to turn on to suppress impedance variation when the first RF signal path is inactive.

Abstract: A switch control circuit includes a positive voltage bias node, a voltage-regulated positive supply rail coupled to the positive voltage bias node, a charge pump coupled to a charge pump supply node, and a current source positive supply rail coupled to the charge pump supply node and configured to supply the charge pump.

Abstract: Disclosed are devices and methods related to radio-frequency (RF) switches having silicon-on-insulator (SOI) field-effect transistors (FETs). In some embodiments, an RF switch can include an FET with shaped source, drain, and gate selected to yield a reduced per-area value of resistance in linear operating region (Rds-on). In some implementations, a plurality of such FETs can be connected in series to allow use of SOI technology in high power RF switching applications while maintaining a relatively small die size.

Abstract: A switch bias control circuit includes a level shifter and voltage regulator circuitry configured to receive a voltage reference signal, provide a first voltage output at a first node and provide a second voltage output at a second node, the first node and the second node being at least partially isolated from one another. coupling circuitry couples the first node to the level shifter and couples the second node to a negative voltage generator.

Abstract: Disclosed are devices and methods related to radio-frequency (RF) switches having silicon-on-insulator (SOI) field-effect transistors (FETs). In some embodiments, an RF switch can include an FET with shaped source, drain, and gate selected to yield a reduced per-area value of resistance in linear operating region (Rds-on). In some implementations, a plurality of such FETs can be connected in series to allow use of SOI technology in high power RF switching applications while maintaining a relatively small die size.

Abstract: Apparatus and methods for level shifting in a radio frequency system are provided. In certain configurations, a radio frequency system includes a level shifter operable to provide level shifting to an input signal. The level shifter is biased by a bias voltage and powered by a supply voltage and a charge pump voltage. The radio frequency system further includes a charge pump configured to provide the charge pump voltage and to receive a mode signal operable to enable the charge pump in a first state and to disable the charge pump in a second state. The radio frequency system further includes a level shifter control circuit configured to control the bias voltage to track the charge pump voltage when the mode signal is in the first state, and to control the bias voltage with the supply voltage when the mode signal is in the second state.

Abstract: Aspects of this disclosure relate to voltage generators, such as negative voltage generators. In certain configurations, a negative voltage generator includes a charge pump controllable by a clock signal and configured to provide a negative voltage at an output node, an oscillator configured to activate based on an enable signal and to provide the clock signal to the charge pump, a comparator configured to generate the enable signal based on comparing a feedback voltage with a reference value, a voltage divider electrically connected between a positive voltage node and the output node and configured to generate the feedback voltage at a feedback node, and a start-up capacitor electrically connected between the positive voltage node and the feedback node and configured to control a settling time of the feedback voltage.

Abstract: Apparatus and methods for multi-mode charge pumps are disclosed herein. In certain configurations, a multi-mode charge pump includes an output terminal, a mode control circuit that operates the multi-mode charge pump in a selected mode, a first switched capacitor, a capacitor charging circuit, and a plurality of switches. The capacitor charging circuit connects a first end of the first switched capacitor to a charging voltage in a first phase of a clock signal, and connects the first end of the first switched capacitor to a reference voltage in a second phase of the clock signal. The charging voltage has a voltage level that changes based on the selected mode. The plurality of switches connect a second end of the first switched capacitor to the reference voltage in the first phase, and connect the second end of the first switched capacitor to the output terminal in the second phase.

Abstract: A switch bias control circuit includes a level shifter and voltage regulator circuitry configured to receive a voltage reference signal, provide a first voltage output at a first node and provide a second voltage output at a second node, the first node and the second node being at least partially isolated from one another. coupling circuitry couples the first node to the level shifter and couples the second node to a negative voltage generator.

Abstract: Apparatus and methods for charge pumps are disclosed herein. In certain configurations, a charge pump includes a mode control circuit, a clock generation circuit that generates a clock signal, two or more switched capacitors, and a capacitor charging circuit used to charge the switched capacitors in response to transitions of the clock signal. The mode control circuit can be used to operate the charge pump in one of a plurality of modes associated with different clock signal oscillation frequencies and with different power supply voltages of the capacitor charging circuit. For example, in certain configurations, the selected mode can control an oscillation frequency of clock signal and a voltage level of a power supply voltage used by the capacitor charging circuit when charging the switched capacitors.

Abstract: Apparatus and methods for level shifting in a radio frequency system are provided. In certain configurations, a radio frequency system includes a level shifter operable to provide level shifting to an input signal. The level shifter is biased by a bias voltage and powered by a supply voltage and a charge pump voltage. The radio frequency system further includes a charge pump configured to provide the charge pump voltage and to receive a mode signal operable to enable the charge pump in a first state and to disable the charge pump in a second state. The radio frequency system further includes a level shifter control circuit configured to control the bias voltage to track the charge pump voltage when the mode signal is in the first state, and to control the bias voltage with the supply voltage when the mode signal is in the second state.