Various embodiments relate to a free running oscillator, including: a voltage controlled oscillator circuit including an input configured to receive an input voltage and an output configured to provide an oscillation signal, wherein the input voltage controls a frequency of the oscillation signal; a frequency to voltage circuit including an input configured to receive the oscillation signal and an output configured to produce a voltage dependent on a frequency of the oscillation signal; a comparison circuit including an input and an output comprising: a first amplifier including a first input, a second input, and an output, wherein the output is based upon a difference in voltage between the first input and the second input, wherein the first input received one of a reference voltage and the output of frequency to voltage circuit; a second amplifier including a first input, a second input, and an output, wherein the output is based upon a difference in voltage between the first input and the second input, first input is connected to the comparator output, the second inputs is connected to the second amplifier output; a sampling capacitor connected between the second input of the first amplifier and a ground; and an integration capacitor connected between the comparator output and the ground.

An oscillation circuit includes resistors with tap points for high/low reference voltages. An RC network coupled in parallel with the resistors includes a first capacitor to vary a first voltage input and a second capacitor to generate a second voltage input. A first comparator alternately compares the voltage inputs with the low reference voltage to generate oscillation outputs. A PTAT current DAC supplies an injection current to a resistor of the series of resistors that variably modulates the reference voltages. A second comparator alternately compares the voltage inputs with the high reference voltage and controls generation of an adaptive bias current to first comparator near a switching threshold voltage range thereof. A chop switch matrix alternately flips voltage reference inputs to input terminals of first comparator. A multiplexer alternately inverts a polarity of the oscillation outputs in concert with alternately flipping the voltage reference inputs by the chop switch matrix.

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.

A clock and data recovery circuit includes a sampling circuit, a phase detector, a first processing circuit, a second processing circuit and an oscillator circuit. The sampling circuit is configured to sample input data according to an output clock, and generate a sampling result. The phase detector is configured to generate a detection result according to the sampling result. The first processing circuit is configured to process the sampling result to generate a first digital code. The second processing circuit is configured to accumulate a portion of the first digital code to generate a second digital code. A rate of change of a code value of the second digital code is slower than a rate of change of a code value of the first digital code. The oscillator circuit is configured to generate the output clock according to the detection result, the first digital code and the second digital code.

A relaxation oscillator 2 comprises: a comparator 4 comprising: a differential pair of transistors 140, 142, 144. 40, 42, 44; a static current source 32; and a dynamic current source 32; and at least one energy storage component 8, 14;
wherein the comparator 4 is arranged to provide an output signal which triggers the charging or discharging of the energy storage component 8, the dynamic current source 32 being enabled prior to the charging or discharging being triggered and disabled after a predetermined time.

An oscillation circuit includes first and second constant current circuits, first and second switch circuits, first and second MOS transistors, and an output port. The first constant current circuit is connected to one port of a capacitor. The first MOS transistor has a gate and a drain connected to the second constant current circuit and a source connected to another port of the capacitor. The second MOS transistor has a gate connected to the gate of the first MOS transistor, and a drain connected to the one port of the capacitor. The second switch circuit is connected between a source of the second MOS transistor and a second power supply terminal. The output port outputs a signal based on a voltage of the one port. Turn-on and turn-off of the first and second switch circuits are controlled by the signal of the output port and an inverted signal.

Relaxation oscillator and method for providing an output frequency. For example, the relaxation oscillator includes a reference generator, a capacitor, a first comparator, a second comparator, a latch, and a temperature compensation circuit. The reference generator is configured to generate a first bias current, a first bias voltage and a second bias voltage. The capacitor is configured to be charged by a charging current to generate a charged voltage, and the charging current is generated based on at least the first bias current. The first comparator is configured to compare the charged voltage and the first bias voltage to generate a first comparison result, and the second comparator is configured to compare the charged voltage and the second bias voltage to generate a second comparison result. The latch is configured to generate a clock signal based on at least the first comparison result and the second comparison result.

In one form, a spread spectrum clock generator includes an oscillator and a digital modulator. The oscillator has a control input for setting an output frequency, and an output for providing a clock output signal. The digital modulator is responsive to the clock output signal to provide a control code to the control input of the oscillator as a periodic signal with a plurality of discrete steps, wherein the digital modulator provides said control code at each of said plurality of discrete steps for substantially a predetermined time.

A stress compensated oscillator circuitry comprises a sensor arrangement for providing a sensor output signal S.sub.Sensor, wherein the sensor output signal S.sub.Sensor is based on an instantaneous stress or strain component a in the semiconductor substrate, a processing arrangement for processing the sensor output signal S.sub.Sensor and providing a control signal S.sub.Control depending on the instantaneous stress or strain component σ in the semiconductor substrate, and an oscillator arrangement for providing an oscillator output signal S.sub.osc having an oscillator frequency f.sub.osc based on the control signal S.sub.Control, wherein the control signal S.sub.Control controls the oscillator output signal S.sub.osc, and wherein the control signal S.sub.Control reduces the influence of the instantaneous stress or strain component σ in the semiconductor substrate onto the oscillator output signal S.sub.osc, so that the oscillator circuitry provides a stress compensated oscillator output signal.

Systems and methods are disclosed for wide frequency range voltage controlled oscillators. For example, an apparatus includes a Voltage Controlled Oscillator (VCO) including a delay cell which includes first and second current sources provided in parallel with one another. The first current source is controlled by a voltage control input connected to a voltage control terminal and the second current source is controlled by a bias voltage input connected to a bias voltage terminal. The first current source provides an alternate current path in the delay cell when the second current source is off. The delay cell is operable to receive an input and produce an output using the alternate current path.