According to one embodiment, a dual voltage controlled oscillator (VCO) circuit includes a first VCO and a second VCO. The first VCO includes: a first variable capacitor having an input node, a first output node, and a second output node, a second variable capacitor coupled in parallel with the first variable capacitor, a first transistor, and a second transistor, where the first transistor has a first drain coupled to the first output node, a first gate coupled to the second output node, and a first source coupled to a ground, where the second transistor has a second drain coupled to the second output node and a second gate coupled to the first output node, and a second source coupled to the ground. The dual VCO circuit includes a second VCO mirroring the first VCO, a first and a second inductors coupled to the first and the second VCO respectively.

According to one embodiment, a dual voltage controlled oscillator (VCO) circuit includes a first VCO and a second VCO. The first VCO includes: a first variable capacitor having an input node, a first output node, and a second output node, a second variable capacitor coupled in parallel with the first variable capacitor, a first transistor, and a second transistor, where the first transistor has a first drain coupled to the first output node, a first gate coupled to the second output node, and a first source coupled to a ground, where the second transistor has a second drain coupled to the second output node and a second gate coupled to the first output node, and a second source coupled to the ground. The dual VCO circuit includes a second VCO mirroring the first VCO, a first and a second inductors coupled to the first and the second VCO respectively.

Disclosed herein is an apparatus that includes a variable clock divider configured to divide a first clock signal to generate a second clock signal, a delay circuit configured to delay the second clock signal to generate a third clock signal, and a phase detector configured to compare phases of the second and third clock signals. The variable clock divider has a division ratio that is variable based, at least in part, on a delay amount of the delay circuit.

Disclosed herein is an apparatus that includes a variable clock divider configured to divide a first clock signal to generate a second clock signal, a delay circuit configured to delay the second clock signal to generate a third clock signal, and a phase detector configured to compare phases of the second and third clock signals. The variable clock divider has a division ratio that is variable based, at least in part, on a delay amount of the delay circuit.

A frequency divider includes a signal injection circuit and an oscillating circuit. The signal injection circuit includes a transistor of which a gate receives an input signal with an input frequency, a drain and a source cooperatively provide a first differential signal pair, and a body receives a biasing voltage. The two circuits cooperate to form a tank circuit having a free-running frequency and defining a frequency locking range which is around N times the free-running frequency and within which the input frequency falls. The tank circuit generates a second differential signal pair that is related to the first differential signal pair and that has an oscillating frequency which is one-N.sup.th the input frequency.

A frequency divider includes a signal injection circuit and an oscillating circuit. The signal injection circuit includes a transistor of which a gate receives an input signal with an input frequency, a drain and a source cooperatively provide a first differential signal pair, and a body receives a biasing voltage. The two circuits cooperate to form a tank circuit having a free-running frequency and defining a frequency locking range which is around N times the free-running frequency and within which the input frequency falls. The tank circuit generates a second differential signal pair that is related to the first differential signal pair and that has an oscillating frequency which is one-N.sup.th the input frequency.

A frequency divider includes a signal injection circuit and an oscillating circuit. The signal injection circuit includes a transistor of which a gate receives an input signal with an input frequency, a drain and a source cooperatively provide a first differential signal pair, and a body receives a biasing voltage. The two circuits cooperate to form a tank circuit having a free-running frequency and defining a frequency locking range which is around N times the free-running frequency and within which the input frequency falls. The tank circuit generates a second differential signal pair that is related to the first differential signal pair and that has an oscillating frequency which is one-N.sup.th the input frequency.

A frequency divider includes a signal injection circuit and an oscillating circuit. The signal injection circuit includes a transistor of which a gate receives an input signal with an input frequency, a drain and a source cooperatively provide a first differential signal pair, and a body receives a biasing voltage. The two circuits cooperate to form a tank circuit having a free-running frequency and defining a frequency locking range which is around N times the free-running frequency and within which the input frequency falls. The tank circuit generates a second differential signal pair that is related to the first differential signal pair and that has an oscillating frequency which is one-N.sup.th the input frequency.

A PLL has a tunable resonator including an inductance and variable capacitance coupled between first and second nodes, and capacitances coupleable between the nodes. A control node is coupled to the variable capacitance and receives a control signal for tuning the resonator. A biasing circuit biases the resonator to generate an output. A PFD circuit senses timing offset of the output with respect to a reference and asserts first or second digital signals dependent on the sign of the timing offset. A charge pump generates the control signal based on the first and second digital signals. A timer asserts a timing signal in response to a pulse sensed in a reset signal and de-asserts the timing signal after a time interval. A calibrator couples selected capacitances between the first and second nodes as a function of the second digital signal, in response to assertion of the timing signal.

A PLL has a tunable resonator including an inductance and variable capacitance coupled between first and second nodes, and capacitances coupleable between the nodes. A control node is coupled to the variable capacitance and receives a control signal for tuning the resonator. A biasing circuit biases the resonator to generate an output. A PFD circuit senses timing offset of the output with respect to a reference and asserts first or second digital signals dependent on the sign of the timing offset. A charge pump generates the control signal based on the first and second digital signals. A timer asserts a timing signal in response to a pulse sensed in a reset signal and de-asserts the timing signal after a time interval. A calibrator couples selected capacitances between the first and second nodes as a function of the second digital signal, in response to assertion of the timing signal.