Patent ID: 8373502

Claim:
A relaxation oscillator for generating a first oscillation signal and a second oscillation signal, comprising: a reference-voltage providing circuit for providing a first reference voltage and a second reference voltage, wherein the first reference voltage being higher than the second reference voltage; a first switch, a second switch, a third switch, a fourth switch, a fifth switch and a sixth switch, each receiving a digital control signal, having a first terminal and a second terminal, configured to establish an electrical connection between the first terminal and the second terminal when the digital control signal having a value of logical 1, and to disconnect the first terminal from the second terminal when the digital control signal having a value of logical 0, wherein the first terminals of the first, third and fifth switches are connected to the first reference voltage, and the first terminals of the second, fourth and sixth switches are connected to the second reference voltage; a transconductance amplifier having a non-inverting input, an inverting input, a tuning-voltage input and an output, for generating an output current at the output with a current value determined by a transconductance value of the transconductance amplifier multiplied by the voltage difference between the non-inverting input and the inverting input, wherein the non-inverting input is connected to the second terminals of the third and fourth switches, the inverting input is connected to the second terminals of the fifth and sixth switches, and wherein the transconductance value is variable and is controlled by an external input tuning voltage applied at the tuning-voltage input; a capacitor connecting between the output of the transconductance amplifier and an electrical ground; and a comparator having a non-inverting input, an inverting input, a non-inverting output and an inverting output, for generating a first digital signal at the non-inverting output and a second digital signal at the inverting output, wherein the non-inverting input is connected to the second terminals of the first and second switches, and the inverting input is connected to the output of the transconductance amplifier; wherein the first digital signal having a logical 1 value when the voltage difference between the non-inverting input of the comparator and the inverting input of the comparator being positive, and a logical 0 value when the voltage difference between the non-inverting input of the comparator and the inverting input of the comparator being negative; wherein the first digital signal is the digital control signals for the first, the third, and the sixth switches; wherein the second digital signal is the digital control signals for the second, the fourth, and the fifth switches; wherein the first digital signal is the first oscillation signal of the relaxation oscillator; and wherein the second digital signal is the second oscillation signal of the relaxation oscillator.