Phase noise reduction in voltage controlled oscillators

• US 10,666,191 B2
• Filed: 12/05/2017
• Issued: 05/26/2020
• Est. Priority Date: 01/10/2014
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Valdes-Garcia, Alberto, Sadhu, Bodhisatwa
• Primary Examiner(s): Kinkead, Arnold M
• Application Number:
  US15/832,069
• Publication Number:
  US 20180109226A1
• Time in Patent Office: 903 Days
• Field of Search: 331167, 331117 FE, 331117 R, 331177 V
• CPC Class Codes: G06F 2119/10 Noise analysis or noise optimisation
• CPC Class Codes: G06F 30/30 Circuit design
• CPC Class Codes: G06F 30/327 Logic synthesis; Behaviour synthesis, e.g. mapping logic, HDL to netlist, high-level language to RTL or netlist
• CPC Class Codes: G06F 30/36 Circuit design at the analogue level
• CPC Class Codes: H03B 1/00 Details
• CPC Class Codes: H03B 2200/0038 including a current mirror
• CPC Class Codes: H03B 2200/009 Reduction of phase noise
• CPC Class Codes: H03B 5/1212 the amplifier comprising a pair of transistors, wherein an output terminal of each being connected to an input terminal of the other, e.g. a cross coupled pair
• CPC Class Codes: H03B 5/1215 the current source or degeneration circuit being in common to both transistors of the pair, e.g. a cross-coupled long-tailed pair
• CPC Class Codes: H03B 5/1228 the amplifier comprising one or more field effect transistors
• CPC Class Codes: H03B 5/1243 the means comprising voltage variable capacitance diodes
• CPC Class Codes: H03B 5/1281 the parameter being the amount of feedback

Abstract

A voltage controlled oscillator (VCO), a method of designing a voltage controlled oscillator, and a design structure comprising a semiconductor substrate including a voltage controlled oscillator are disclosed. In one embodiment, the VCO comprises an LC tank circuit for generating an oscillator output at an oscillator frequency, and an oscillator core including cross-coupled semiconductor devices to provide feedback to the tank circuit. The VCO further comprises a supply node, a tail node, and a noise by-pass circuit connected to the supply and tail nodes, in parallel with the tank circuit and the oscillator core. The by-pass circuit forms a low-impedance path at a frequency approximately twice the oscillator frequency to at least partially immunize the oscillator core from external noise and to reduce noise contribution from the cross-coupled semiconductor devices.

Claims

1. A design structure comprising:

a machine readable hardware medium having machine readable instructions tangibly embodied therein for design, manufacturing, or testing a semiconductor device, the machine readable instructions executable by a computer design system to cause the computer design system;

to generate a machine readable representation of a voltage controlled oscillator (VCO), said machine readable representation being encoded in a machine readable hardware storage media;

said encoded machine readable representation comprising;

encoded machine readable representation of an LC tank circuit for generating an oscillator output signal at an oscillator frequency (f_o);

encoded machine readable representation of an oscillator core including first and second cross-coupled semiconductor devices connected to the tank circuit to provide regenerative feedback to the tank circuit to help maintain the oscillator output stable;

a encoded machine readable representation of a supply node connected to the oscillator core for connecting the VCO to a voltage source;

encoded machine readable representation of a tail node connected to the oscillator core for connecting the VCO to a current source; and

encoded machine readable representation of a noise by-pass circuit connected to the supply node and to the tail node, in parallel with the LC tank circuit and the oscillator core, and forming a low-impedance path at a frequency approximately twice the oscillator frequency to at least partially immunize the oscillator core from external noise and to reduce noise contribution from the cross-coupled semiconductor devices; and

wherein the computer design system includes a lithography machine for generating masks.

2. The design structure according to claim 1, wherein the noise by-pass circuit comprises a series resonance tuned to resonate at approximately twice the oscillator frequency.

3. The design structure according to claim 2, wherein the noise by-pass circuit includes a capacitor and an inductor located in series.

4. The design structure according to claim 2, wherein the noise by-pass circuit includes a capacitor and a transmission line located in series.

5. The design structure according to claim 2, wherein the VCO further comprises a frequency control to apply a variable signal to the by-pass circuit to adjust the frequency at which the noise by-pass circuit resonates.

6. The design structure according to claim 1, wherein the encoded machine readable representation of the VCO comprises a netlist comprising a list of wires, discrete components, logic gates, control circuits, and I/O devices of the voltage controlled oscillator.

7. The design structure according to claim 6, wherein the netlist is programmed into a programmable gate array.

8. A computer design system comprising:

a lithography machine for generating masks; and

a machine readable hardware medium having machine readable instructions tangibly embodied therein for designing a semiconductor device, the machine readable instructions executable by the computer design system to instantiate a design of a voltage controlled oscillator in a programmable gate array,

the instantiated design comprising;

a machine readable representation, encoded in the programmable gate array, of an LC tank circuit for generating an oscillator output signal at an oscillator frequency (f_o);

a machine readable representation, encoded in the programmable gate array, of an oscillator core including first and second cross-coupled semiconductor devices connected to the tank circuit to provide regenerative feedback to the tank circuit to help maintain the oscillator output stable;

a machine readable representation, encoded in the programmable gate array, of a supply node connected to the oscillator core for connecting the VCO to a voltage source;

a machine readable representation, encoded in the programmable gate array, of a tail node connected to the oscillator core for connecting the VCO to a current source; and

a machine readable representation, encoded in the programmable gate array, of a noise by-pass circuit connected to the supply node and to the tail node, in parallel with the LC tank circuit and the oscillator core, and forming a low-impedance path at a frequency approximately twice the oscillator frequency to at least partially immunize the oscillator core from external noise and to reduce noise contribution from the cross-coupled semiconductor devices.