Programmable capacitors and methods of using the same

Abstract

In a first aspect, a first method of adjusting capacitance of a semiconductor device is provided. The first method includes the steps of (1) providing a transistor including a dielectric material having a dielectric constant of about 3.9 to about 25, wherein the transistor is adapted to operate in a first mode to provide a capacitance and further adapted to operate in a second mode to change a threshold voltage of the transistor from an original threshold voltage to a changed threshold voltage such that the changed threshold voltage affects a capacitance provided by the transistor when operated in the first mode; and (2) employing the transistor in a circuit. Numerous other aspects are provided.

1 . A semiconductor device having an adjustable capacitance, comprising:
 a transistor formed on a substrate having:
 a gate region including a dielectric material having a dielectric constant of about 3.9 to about 25; 
   wherein the transistor is adapted to operate in a first mode to provide a capacitance; and   wherein the transistor is adapted to operate in a second mode to change a threshold voltage of the transistor from an original threshold voltage to a changed threshold voltage such that the changed threshold voltage affects a capacitance provided by the transistor when operated in the first mode.   
   
   
       2 . The semiconductor device of  claim 1  wherein:
 the semiconductor device further includes a source diffusion region and a drain diffusion region; and   the transistor is adapted to operate in the first mode to provide the capacitance when a voltage is applied to the gate region, and the source diffusion region, drain diffusion region and substrate are grounded.   
   
   
       3 . The semiconductor device of  claim 1  wherein the dielectric material is hafnium silicon oxide (HfSiO). 
   
   
       4 . The semiconductor device of  claim 1  wherein the transistor is adapted to provide low-leakage capacitance. 
   
   
       5 . The semiconductor device of  claim 1  wherein the transistor is further adapted to provide a capacitance of about 0.1 fF/μm 2  to about 2.0 fF/μm 2 . 
   
   
       6 . The semiconductor device of  claim 1  wherein the transistor is adapted to store a capacitance state. 
   
   
       7 . A system adapted to provide a variable capacitance, comprising:
 a circuit including at least one transistor including a dielectric material having a dielectric constant of about 3.9 to about 25;   wherein each of the at least one transistor is adapted to operate in a first mode to provide a capacitance;   wherein each of the at least one transistor is adapted to operate in a second mode to change a threshold voltage of the transistor from an original threshold voltage to a changed threshold voltage such that the changed threshold voltage affects a capacitance provided by the transistor when operated in the first mode; and   wherein a capacitance provided by the circuit is based on the capacitance provided by each of the at least one transistor.   
   
   
       8 . The system of  claim 7  wherein the circuit is a voltage-controlled oscillator of a phase-locked loop. 
   
   
       9 . The system of  claim 7  wherein the circuit is a binary weighted array of the at least one transistor. 
   
   
       10 . The system of  claim 7  further comprising control circuitry coupled to one or more of the at least one transistor and adapted to:
 cause one or more of the at least one transistor to operate in the first mode; and   cause one or more of the at least one transistor to operate in the second mode.   
   
   
       11 . The system of  claim 10  wherein:
 the circuit is a voltage-controlled oscillator of a phase-locked loop (PLL); and   the control circuitry includes a multiplexer adapted to:
 selectively output a functional voltage to the at least one transistor such that the at least one transistor operates in the first mode to provide a capacitance based on the functional voltage; and 
 selectively output a programming voltage to the at least one transistor such that the at least one transistor operates in the second mode to change a threshold voltage of the at least one transistor based on the programming voltage. 
   
   
   
       12 . The system of  claim 11  wherein the functional voltage is the control voltage of the PLL. 
   
   
       13 . The system of  claim 11  wherein the control circuitry is further adapted to:
 selectively output a functional voltage to the at least one transistor such that the at least one transistor operates in the first mode to provide a first transistor capacitance based on the functional voltage such that the circuit provides a first circuit capacitance that does not lock the PLL within a predetermined distance from a center control voltage;   selectively output a programming voltage to the at least one transistor such that a threshold voltage of the at least one transistor changes from an original threshold voltage to a changed threshold voltage such that the changed threshold voltage affects a capacitance provided by the transistor, and therefore the circuit, when operated in the first mode; and   thereafter, selectively output the functional voltage to the at least one transistor such that the at least one transistor operates in the first mode to provide a second transistor capacitance based on the functional voltage such that the circuit provides a second circuit capacitance that locks the PLL.   
   
   
       14 . The system of  claim 10  wherein:
 the circuit includes a first set of one or more of the transistors coupled in parallel to a second set of one or more of the transistors; and   the control circuitry is further adapted to:
 cause transistors in one or more of the first and second sets to operate in the first mode such that the circuit provides a first circuit capacitance; and 
 cause the transistors in one or more of the first and second sets to operate in the second mode such that respective threshold voltages of the transistors change; and 
 thereafter, cause the transistors in one or more of the first and second sets to operate in the first mode such that the circuit provides a second circuit capacitance. 
   
   
   
       15 . The system of  claim 14  wherein the control circuitry includes switches adapted to:
 cause a functional voltage to be applied to transistors in one or more of the first and second sets such that the transistors operate in the first mode and the circuit provides a circuit capacitance; and   cause a programming voltage to be applied to transistors in one or more of the first and second sets such that the transistors operate in the second mode and respective threshold voltages of the transistors change.