Band-Switched Integrated Voltage Controlled Oscillator

• US 20010050598A1
• Filed: 01/14/2000
• Published: 12/13/2001
• Est. Priority Date: 01/14/2000
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Mourant, Jean-Marc, Imbornone, James
• Application Number:
  US09/483,368
• Publication Number:
  US 20010050598A1
• Time in Patent Office: Days
• US Class Current: 331/117.00R
• CPC Class Codes: H03B 5/1218 the generator being of the balanced type
• CPC Class Codes: H03B 5/1228 the amplifier comprising one or more field effect transistors
• CPC Class Codes: H03B 5/1253 the transistors being field-effect transistors
• CPC Class Codes: H03B 5/1265 switched capacitors
• CPC Class Codes: H03B 5/1293 having means for achieving a desired tuning characteristic, e.g. linearising the frequency characteristic across the tuning voltage range
• CPC Class Codes: H03B 5/1296 the feedback circuit comprising a transformer
• CPC Class Codes: H03B 7/06 active element being semiconductor device

Abstract

The source to drain capacitance of a FET device is used by connecting the source and drain together electrically so as to form a two terminal capacitive device which may be switched into and out of a parallel resonant circuit. Thus, sets of FET devices with their sources and drains connected together are employed in a circuit which produces and output voltage signal at a frequency which is tunable within a plurality of different individual bands. The resultant voltage controlled oscillator is particularly useful in cellular telephone and related wireless systems and/or in any other situation where integrated high frequency voltage control oscillator circuits are desired.

Claims

1. A two-terminal capacitor comprising;

a field effect transistor having a source, a Gate and a drain and electrical connections thereto wherein said source and drain are thereby electrically connected together to provide a first terminal of said capacitor, said Gate connection providing said second terminal.

2. The capacitor of

claim 1

in which said transistor is a MOSFET.

3. A voltage controlled tuning circuit comprising:

a resonant circuit including a capacitor;

a plurality of pairs of capacitive elements with at least one of said capacitive elements comprising a FET device with its source and drain connected together to form one terminal of a two terminal capacitive element with the base of said FET device being the second terminal of said at least one capacitive element, with each of said members of said pairs being connected in series, and with said pairs of capacitive elements being connected in parallel with the capacitor in said resonant circuit; and

means for varying the capacitance of selected ones of said pairs of elements.

4. The circuit of

claim 3

in which said varying means comprises circuits for applying voltage to select ones of said Gates.

5. The circuit of

claim 3

in which each one of said pairs comprises FET devices.