A relaxation oscillator includes an adjustable reference circuit generator to produce a reference current which is applied to a charging circuit. The charging circuit is configured to charge a capacitive node as a function of the reference current and a capacitance of an adjustable capacitor that is operably coupled to the capacitive node. A comparator having inputs operatively coupled to a reference voltage node and to the capacitive node, generates a comparator output. A control circuit alternatively enables the charging circuit to charge the capacitive node and to discharge the capacitive node in response to changes in the comparator output. Also, the control circuit outputs and oscillator output signal have an oscillator period as a function of the adjustable capacitance and the adjustable reference current.

A relaxation oscillator includes an adjustable reference circuit generator to produce a reference current which is applied to a charging circuit. The charging circuit is configured to charge a capacitive node as a function of the reference current and a capacitance of an adjustable capacitor that is operably coupled to the capacitive node. A comparator having inputs operatively coupled to a reference voltage node and to the capacitive node, generates a comparator output. A control circuit alternatively enables the charging circuit to charge the capacitive node and to discharge the capacitive node in response to changes in the comparator output. Also, the control circuit outputs and oscillator output signal have an oscillator period as a function of the adjustable capacitance and the adjustable reference current.

An oscillator circuit includes a total of N (N≥2) class-D oscillator circuits stacked together between a supply voltage node and a reference voltage node. The output ports of adjacent class-D oscillator circuits in the disclosed oscillator circuit are coupled together by capacitors to ensure frequency and phase synchronization for the frequency signals generated by the class-D oscillator circuits. Compared with a reference oscillator circuit formed of a single class-D oscillator circuit, the oscillation amplitude of each of the class-D oscillator circuits in the disclosed oscillator circuit is 1/N of that of the reference oscillator circuit, and the current consumption of the disclosed oscillator circuit is 1/N of that of the reference oscillator circuit.

An oscillator circuit includes a total of N (N≥2) class-D oscillator circuits stacked together between a supply voltage node and a reference voltage node. The output ports of adjacent class-D oscillator circuits in the disclosed oscillator circuit are coupled together by capacitors to ensure frequency and phase synchronization for the frequency signals generated by the class-D oscillator circuits. Compared with a reference oscillator circuit formed of a single class-D oscillator circuit, the oscillation amplitude of each of the class-D oscillator circuits in the disclosed oscillator circuit is 1/N of that of the reference oscillator circuit, and the current consumption of the disclosed oscillator circuit is 1/N of that of the reference oscillator circuit.

In an example, a system includes an oscillator circuit on a chip. The oscillator circuit includes a charging current generator including a current mirror and an amplifier, where the amplifier is coupled to a pin on the chip, and where the pin is adapted to be coupled to an external resistor, where the external resistor is external to the chip. The oscillator circuit also includes oscillator circuitry coupled to the charging current generator, where the oscillator circuitry includes a comparator, a phase generator, a first capacitor coupled to a first switch, and a second capacitor coupled to a second switch. The oscillator circuit includes leakage circuitry coupled to the current mirror, where the leakage circuitry is configured to draw a current from the current mirror proportional to a leakage current flowing through the external resistor from circuitry internal to the chip.

In an example, a system includes an oscillator circuit on a chip. The oscillator circuit includes a charging current generator including a current mirror and an amplifier, where the amplifier is coupled to a pin on the chip, and where the pin is adapted to be coupled to an external resistor, where the external resistor is external to the chip. The oscillator circuit also includes oscillator circuitry coupled to the charging current generator, where the oscillator circuitry includes a comparator, a phase generator, a first capacitor coupled to a first switch, and a second capacitor coupled to a second switch. The oscillator circuit includes leakage circuitry coupled to the current mirror, where the leakage circuitry is configured to draw a current from the current mirror proportional to a leakage current flowing through the external resistor from circuitry internal to the chip.

Provided is a relaxation oscillating circuit, which comprises a charging circuit, a discharging circuit, a switch circuit, a charging-discharging capacitor and an output circuit. The charging circuit comprises a first current source and a first isolating transistor. The discharging circuit comprises a second current source and a second isolating transistor. The switch circuit comprises a main charging transistor and an auxiliary charging transistor arranged as mirror and a main discharging transistor and an auxiliary discharging transistor arranged as mirror. The main charging transistor and the main discharging transistor are alternately conducted. According to a voltage of the charging-discharging capacitor, the output circuit outputs a clock signal and a control signal. The clock signal is connected to control ends of the auxiliary charging transistor and the auxiliary discharging transistor, and the control signal is connected to control ends of the main charging transistor and the main discharging transistor.

Provided is a relaxation oscillating circuit, which comprises a charging circuit, a discharging circuit, a switch circuit, a charging-discharging capacitor and an output circuit. The charging circuit comprises a first current source and a first isolating transistor. The discharging circuit comprises a second current source and a second isolating transistor. The switch circuit comprises a main charging transistor and an auxiliary charging transistor arranged as mirror and a main discharging transistor and an auxiliary discharging transistor arranged as mirror. The main charging transistor and the main discharging transistor are alternately conducted. According to a voltage of the charging-discharging capacitor, the output circuit outputs a clock signal and a control signal. The clock signal is connected to control ends of the auxiliary charging transistor and the auxiliary discharging transistor, and the control signal is connected to control ends of the main charging transistor and the main discharging transistor.

An oscillator circuit includes a first comparator that outputs a first signal indicative of a comparison result between an input potential and a threshold, a second comparator that outputs a second signal indicative of a comparison result between an input potential and the threshold, a RS flip-flop circuit that receives the first signal and the second signal and outputs first and second oscillation signals, a first charge/discharge unit that charges and discharges a first capacitor based on the first oscillation signal, a second charge/discharge unit that charges and discharges a second capacitor based on the second oscillation signal, a first dummy switch controlled to be on and off according to the second oscillation signal and adding a predetermined capacity to a first node, and a second dummy switch controlled to be on and off according to the first oscillation signal and adding a predetermined capacity to a second node.

An oscillator circuit includes a first comparator that outputs a first signal indicative of a comparison result between an input potential and a threshold, a second comparator that outputs a second signal indicative of a comparison result between an input potential and the threshold, a RS flip-flop circuit that receives the first signal and the second signal and outputs first and second oscillation signals, a first charge/discharge unit that charges and discharges a first capacitor based on the first oscillation signal, a second charge/discharge unit that charges and discharges a second capacitor based on the second oscillation signal, a first dummy switch controlled to be on and off according to the second oscillation signal and adding a predetermined capacity to a first node, and a second dummy switch controlled to be on and off according to the first oscillation signal and adding a predetermined capacity to a second node.