VARACTOR BANK SWITCHING BASED ON NEGATIVE CONTROL VOLTAGE GENERATION

• US 20090243702A1
• Filed: 12/09/2008
• Published: 10/01/2009
• Est. Priority Date: 03/31/2008
• Status: Abandoned Application

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Weiss, Jonas R., Morf, Thomas E., Kossel, Marcel A.
• Application Number:
  US12/331,158
• Publication Number:
  US 20090243702A1
• Time in Patent Office: Days
• US Class Current: 327/427
• 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 5/1265 switched capacitors
• CPC Class Codes: H03J 2200/01 Circuitry controlling the selecting or switching action
• CPC Class Codes: H03J 2200/10 Tuning of a resonator by means of digitally controlled capacitor bank
• CPC Class Codes: H03J 3/185 with varactors, i.e. voltage variable reactive diodes
• CPC Class Codes: H03J 5/244 using electronic means
• CPC Class Codes: H03K 2017/066 Maximizing the OFF-resistance instead of minimizing the ON-resistance

Abstract

A method and apparatus for varactor bank switching for a voltage controlled oscillator is disclosed. Varactor bank switching involves generating a negative bias voltage signal as a control signal for a varactor bank switch in an off-state, the varactor bank switch comprising a pass-gate circuit including switching transistors. Generating the negative bias voltage signal includes employing an active rectifier circuit running at the speed of an oscillation signal, the negative bias voltage signal maintaining the gate-source voltage of the pass-gate circuit below a threshold voltage to prevent said switching transistors from becoming conductive in an off-state.

Claims

1. A system for varactor bank switching for an oscillator, comprising:

a voltage controller configured for generating a negative bias voltage signal as a control signal for a varactor bank switch in an off-state, the varactor bank switch comprising a pass-gate circuit including switching transistors, the voltage controller comprising an active rectifier circuit configured for running at the speed of an oscillation signal, the negative bias voltage signal maintaining the gate-source voltage of the pass-gate circuit below a threshold voltage to prevent said switching transistors from becoming conductive in an off-state.