Wideband Voltage-Controlled Oscillator Circuitry

Abstract

An electronic device may include a transceiver with mixer circuitry that up-converts or down-converts signals based on a voltage-controlled oscillator (VCO) signal. The transceiver circuitry may include first, second, third, and fourth VCOs. Each VCO may include a VCO core that receives a control voltage and an inductor coupled to the VCO core. Fixed linear capacitors may be coupled between the VCO cores. A switching network may be coupled between the VCOs. Control circuitry may place the VCO circuitry in one of four different operating modes and may switch between the operating modes to selectively control current direction in each of the inductors. The VCO circuitry may generate the VCO signal within a respective frequency range in each of the operating modes. The VCO circuitry may exhibit a relatively wide frequency range across all of the operating modes while introducing minimal phase noise to the system.

What is claimed is: 
     
         1 . Local oscillator circuitry comprising:
 a first voltage-controlled oscillator (VCO);   a second VCO;   at least one capacitor coupled between the first VCO and the second VCO; and   at least one switch coupled between the first VCO and the second VCO and configured to adjust current direction in the first VCO and in the second VCO.   
     
     
         2 . The local oscillator circuitry of  claim 1 , wherein at least the first VCO and the second VCO are configured to generate a local oscillator signal. 
     
     
         3 . The local oscillator circuitry of  claim 2 , wherein the local oscillator signal has a first frequency in a first frequency range when current flows in a first direction in the first VCO and has a second frequency in a second frequency range that is at least partially non-overlapping with respect to the first frequency range when current flows in a second direction in the first VCO opposite the first direction. 
     
     
         4 . The local oscillator circuitry of  claim 1 , wherein the at least one switch is coupled between the first VCO and the second VCO in parallel with the at least one capacitor. 
     
     
         5 . The local oscillator circuitry of  claim 4 , wherein the at least one capacitor comprises a first capacitor and a second capacitor coupled between the first VCO and the second VCO in parallel with the at least one switch. 
     
     
         6 . The local oscillator of  claim 1 , wherein the first VCO comprises a first VCO core and a first inductor and the second VCO comprises a second VCO core and a second inductor. 
     
     
         7 . The local oscillator of  claim 6 , wherein the at least one switch and the at least one capacitor are coupled between the first VCO core and the second VCO core. 
     
     
         8 . The local oscillator of  claim 1 , wherein the first VCO has a first terminal and a second terminal, the second VCO has a third terminal and a fourth terminal, and the at least one switch comprises:
 a first switch coupled between the first terminal and the third terminal; and   a second switch coupled between the second terminal and the fourth terminal.   
     
     
         9 . The local oscillator of  claim 8 , wherein the at least one switch further comprises:
 a third switch coupled between the first terminal and the fourth terminal; and   a fourth switch coupled between the second terminal and the third terminal.   
     
     
         10 . An electronic device comprising:
 wireless circuitry configured to convey radio-frequency signals using a local oscillator signal;   a first voltage-controlled oscillator (VCO);   a second VCO, wherein at least the first VCO and the second VCO are configured to generate the local oscillator signal;   a capacitor coupled between the first VCO and the second VCO; and   at least one switch coupled between the first VCO and the second VCO and configured to reverse current direction in the first VCO and in the second VCO.   
     
     
         11 . The electronic device of  claim 10 , wherein the first VCO has a first terminal and a second terminal, the second VCO has a third terminal and a fourth terminal, and the capacitor is coupled between the first terminal and the third terminal. 
     
     
         12 . The electronic device of  claim 11 , further comprising:
 an additional capacitor coupled between the second terminal and the fourth terminal.   
     
     
         13 . The electronic device of  claim 12 , wherein the at least one switch comprises:
 a first switch coupled between the first terminal and the fourth terminal; and   a second switch coupled between the second terminal and the third terminal.   
     
     
         14 . The electronic device of  claim 13 , wherein the at least one switch further comprises:
 a third switch coupled between the first terminal and the third terminal; and   a fourth switch coupled between the second terminal and the fourth terminal.   
     
     
         15 . The electronic device of  claim 10 , wherein the local oscillator signal is at a first frequency in a first frequency range when current flows in a first direction in the first VCO and is at a second frequency in a second frequency range when current flows in a second direction in the first VCO opposite the first direction, the second frequency range being at least partially non-overlapping with respect to the first frequency range, wherein the first VCO comprises a first VCO core and a first inductor, the second VCO comprises a second VCO core and a second inductor, and the electronic device further comprises:
 one or more processors configured to provide a control signal to the first VCO core that adjusts the first frequency within the first frequency range when the current flows in the first direction and that adjusts the second frequency within the second frequency range when the current flows in the second direction.   
     
     
         16 . A method of operating voltage-controlled oscillator (VCO) circuitry having a first VCO, a second VCO, at least one capacitor coupled between the first VCO and the second VCO, and at least one switch coupled between the first VCO and the second VCO, the method comprising:
 with the at least one switch, placing the first VCO and the second VCO in a first state in which current flows in a first direction in the first VCO;   with the first VCO and the second VCO, outputting a first VCO signal having a first frequency within a first range of frequencies while the first VCO and the second VCO are in the first state;   with the at least one switch, placing the first VCO and the second VCO in a second state in which current flows in a second direction in the first VCO, the second direction being opposite the first direction; and   with the first VCO and the second VCO, outputting a second VCO signal having a second frequency within a second range of frequencies that is at least partially non-overlapping with respect to the first range of frequencies while the first VCO and the second VCO are in the second state.   
     
     
         17 . The method of  claim 16 , wherein current flows in the first direction in the second VCO in the first state and in the first direction in the second VCO in the second state. 
     
     
         18 . The method of  claim 16 , wherein current flows in the first direction in the second VCO in the first state and in the second direction in the second VCO in the second state. 
     
     
         19 . The method of  claim 16 , wherein current flows in the second direction in the second VCO in the first state and in the second direction in the second VCO in the second state. 
     
     
         20 . The method of  claim 16 , wherein current flows in the second direction in the second VCO in the first state and in the first direction in the second VCO in the second state.