Embodiments relate to a circuit including a first circuit branch, a second circuit branch, and an integrator circuit. The first branch includes a first transistor and a first current source to generate a first CTAT voltage signal that includes components corresponding to parasitic base and emitter resistances of the first transistor. The second branch includes a second transistor and a second current source to generate a second CTAT voltage signal that includes components corresponding to parasitic base and emitter resistances of the second transistor. The first and second circuit branches are coupled to the integrator circuit such that the integrator circuit integrates a difference between the first and second CTAT voltage signals such that the integrated signal does not include any components corresponding to parasitic base and emitter resistances.

Certain aspects of the present disclosure provide methods and apparatus for current-limiting protection of an amplifier, such as a power amplifier in a radio frequency (RF) front-end. One example current-limiting circuit generally includes a node coupled to a current source, a plurality of current-sinking devices coupled to the node, one or more switches coupled between the node and at least one of the plurality of current-sinking devices, and a bias circuit having an input coupled to the node and an output for coupling to an input of the amplifier.

One embodiment of the instant disclosure provides a compact lower power thermal sensor that comprises a combination current generator configured to selectively generate a PTAT and a CTAT current; a convertor configured to generate digital output corresponding to the current mirrored by the current-reuse charge pump; and a current-reuse charge pump coupled between the combination current generator and the convertor, configured to mirror the current generated by the combination current generator and selectively establish a charging/discharging path to/from the convertor. The combination current generator selectively generates the PTAT and the CTAT current in accordance with an output state of the convertor, and the current-reuse charge pump selectively charges and discharges a capacitor of the convertor with the PTAT and the CTAT current in accordance with the output state of the convertor.

In examples, a circuit comprises a first current source coupled to a voltage source node. The circuit comprises a resistor having a first resistor terminal and a second resistor terminal, where the first resistor terminal is coupled to the first current source. The circuit comprises a bipolar transistor having a base, a collector, and an emitter, with the base coupled to the first resistor terminal, the emitter coupled to the second resistor terminal, and the collector coupled to the voltage source node. The circuit comprises a second current source coupled to the emitter and the second resistor terminal, with the second current source coupled to a ground node. The circuit comprises a Schmitt trigger having an input coupled to the emitter, the second resistor terminal, and the second current source.

An integrated circuit having power supply circuitry configured to generate a temperature dependent power supply voltage is provided. The power supply circuitry may include temperature sensors formed at different regions on the integrated circuit. The power supply circuitry may use a selected one of the temperature sensors to vary the temperature dependent power supply voltage. The power supply circuitry may include voltage clamping circuitry configured to clip the power supply voltage to an upper fixed voltage level when the power supply voltage exceeds a first predetermined threshold and to clip the power supply voltage to a lower fixed voltage level when the power supply voltage falls below a second predetermined threshold. The power supply circuitry may also include voltage overshoot-undershoot protection circuitry configured to keep the temperature dependent power supply voltage within a specified voltage range in the presence of transient perturbations in the temperature dependent power supply voltage.

In examples, a circuit comprises a first current source coupled to a voltage source node. The circuit comprises a resistor having a first resistor terminal and a second resistor terminal, where the first resistor terminal is coupled to the first current source. The circuit comprises a bipolar transistor having a base, a collector, and an emitter, with the base coupled to the first resistor terminal, the emitter coupled to the second resistor terminal, and the collector coupled to the voltage source node. The circuit comprises a second current source coupled to the emitter and the second resistor terminal, with the second current source coupled to a ground node. The circuit comprises a Schmitt trigger having an input coupled to the emitter, the second resistor terminal, and the second current source.

One example includes a reference voltage generator system. The system includes an amplifier configured to generate a reference voltage based on a respective input voltage provided at each of at least one input of the amplifier. The system also includes at least one input transistor that is coupled to the at least one input of the amplifier and is statically-biased to conduct a current to set an amplitude of the respective input voltage provided at each of the at least one input of the amplifier. Each of the at least one input transistor includes an input terminal that is coupled in series with an input resistor.

An apparatus and method for generating a temperature-compensated reference voltage are disclosed. The apparatus generates substantially equal temperature-compensated currents by controlling (through negative feedback) voltages across separate resistors through which the currents flow, respectively. Two of the temperature-compensated currents are formed by combining (e.g., summing) a complementary to absolute temperature (CTAT) current (I.sub.CTAT) and a proportional to absolute temperature (PTAT) current (I.sub.PTAT). A reference voltage V.sub.REF is produced by configuring the other the temperature-compensated current to flow through an output resistor.

A bandgap reference circuit includes first through fourth bipolar junction transistors (BJTs). The base and collector of the first BJT are shorted together. The second BJT is coupled to the first BJT via a first resistor. The base of the third BJT is coupled to the base of the first BJT. The base and collector of the fourth BJT are coupled together and also are coupled to the base of the second BJT. A second resistor is coupled to the fourth emitter of the fourth BJT. A third resistor is coupled to the second resistor and to the emitter of the second BJT. An operational amplifier has a first input coupled to the first resistor and the collector of the second BJT, a second input coupled to the emitter of the third BJT and the collector of the fourth BJT, and an output coupled to the collectors of the first and third BJTs.

An apparatus and method for generating a temperature-compensated reference voltage are disclosed. The apparatus generates substantially equal temperature-compensated currents by controlling (through negative feedback) voltages across separate resistors through which the currents flow, respectively. Two of the temperature-compensated currents are formed by combining (e.g., summing) a complementary to absolute temperature (CTAT) current (I.sub.CTAT) and a proportional to absolute temperature (PTAT) current (I.sub.PTAT). A reference voltage V.sub.REF is produced by configuring the other the temperature-compensated current to flow through an output resistor.