CPC H03K 3/011 (2013.01) [H03K 3/0231 (2013.01)] | 14 Claims |
1. A free running oscillator, comprising:
a voltage-controlled oscillator circuit comprising:
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 comprising:
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 comprising:
an amplifier including a first input, a second input, a first output, a second output, and a first switch, wherein the first output of the amplifier and the second output of the amplifier are each determined based upon a difference in voltage between the first input of the amplifier and the second input of the amplifier, the first switch selectively activates one of the first output of the amplifier and the second output of the amplifier, and the second output of the amplifier is connected to the second input of the amplifier;
a second switch with an output connected to the first input of the amplifier, a first input connected to a reference voltage, and a second input connected to the output of frequency-to-voltage circuit, wherein the second switch selectively switches between the first input of the second switch and the second input of the second switch to produce an output signal at the output of the second switch;
a sampling capacitor connected between the second input of the amplifier and a ground; and
an integration capacitor connected between an output of the comparison circuit and the ground.
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