Switchable nmos-cmos voltage-controlled oscillator (vco) with shared inductor-capacitor (lc) tank

A method of providing a controlled oscillation frequency using a switchable NMOS-CMOS voltage-controlled oscillator (VCO) comprising a first set of switches coupled between an inductor-capacitor (LC) tank circuit and gates of cross-coupled pairs of CMOS transistors, and a second set of switches coupled between gates of a cross-coupled differential pair of NMOS transistors and drains of the cross-coupled pairs of CMOS transistors, the method comprising:

• applying a control voltage to a control input of the LC tank circuit for voltage tuning;
• monitoring an output signal of the cross-coupled pairs of CMOS transistors to determine an output frequency of the switchable NMOS-CMOS VCO;
• adjusting the control voltage applied to the control input based on the output frequency to achieve a target oscillation frequency;
• and
• outputting the target oscillation frequency of the cross-coupled pairs of CMOS transistors.

A phase-locked loop (PLL) comprising:

• a phase frequency detector (PFD), wherein a first input of the PFD is coupled to a reference frequency source;
• a multi-modulus divider (MMD), wherein an output of the MMD is coupled to a second input of the PFD;
• and
• a switchable n-type metal-oxide semiconductor (NMOS)-complementary MOS (CMOS) voltage-controlled oscillator (VCO) that generates a frequency output coupled to an input of the MMD, wherein the switchable NMOS-CMOS VCO comprises:
• a cross-coupled differential pair of NMOS transistors;
• an inductor-capacitor (LC) tank circuit coupled to the cross-coupled differential pair of NMOS transistors;
• sets of switches coupled to the LC tank circuit;
• and
• cross-coupled pairs of CMOS transistors selectively coupled to the LC tank circuit via the sets of switches.