US 9,330,214 B2Granted

Phase noise reduction in voltage controlled oscillators

AssigneeInternational Business Machines Corporation

InventorsAlberto Valdes-Garcia, Bodhisatwa Sadhu

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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.

Claims10

Dependent claims

A voltage controlled oscillator (VCO) comprising:

an LC tank circuit for generating an oscillator output signal at an oscillator frequency (fo);
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 supply node connected to the tank circuit for connecting the VCO to a voltage source;
a tail node connected to the oscillator core for connecting the VCO to a current source;
and
a noise by-pass circuit having a first end connected to the supply node and a second end connected to the tail node and forming a low-impedance by-pass circuit connecting the supply node and the tail node, in parallel with the LC tank circuit and the oscillator core, 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.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/152,330Filed 10 Jan 2014
Published: US 2015/0200627 A116 Jul 2015
Granted: 3 May 2016
Term ends: Not estimatedThe source records don’t support an estimate.

Classification14 codes

H03B 5/1212
Using multiple transistors for amplification: the amplifier comprising a pair of transistors, wherein an output terminal of each being connected…
G06F 30/30
Computer-aided design [CAD]: circuit design
G06F 30/327
Circuit design at the digital level: logic synthesis; Behaviour synthesis, e.g. mapping logic, HDL to netlist, high-level language to RTL or netlist
G06F 30/36
Circuit design: circuit design at the analogue level