Signal generator

US8022744B2 · kind B2 · utility

Assignee

• Cambridge Semiconductor Limited · GB

Inventors

• Vinod A. Lalithambika · Cambridge, GB
• David M. Garner · London, GB

Key dates

• Filing date: Oct 3, 2008
• Grant date: Sep 20, 2011
• Expiry date: Oct 3, 2028

Classification

• Technology area (CPC G): Physics
• CPC primary: G05F3/30
• WIPO field: Control
• WIPO sector: Instruments

Abstract

Embodiments include a signal generator circuit for generating a time-varying signal, comprising capacitive element; FET to supply to or from the capacitive element a current matched to the FET drain current; a bias voltage generator to provide a bias voltage to the FET gate, wherein: the capacitances per unit area of the capacitive element and the FET gate are matched; the bias voltage is substantially equal to a sum of a first voltage substantially proportional to a reference voltage and a second voltage substantially proportional to temperature; the FET source-gate voltage substantially equal to the sum of the bias voltage and the gate threshold voltage, the bias voltage and a further voltage approximately equal to the gate threshold voltage summed to determine the FET source-gate voltage, the circuit to control a time period of the time-varying signal dependent on the current supply.