Linearization of voltage-controlled amplifier using MOSFET gain control circuit
US5808516A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 28, 1996 |
| Grant date | Sep 15, 1998 |
| Priority date | — |
| Expiry date | Jun 28, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03G1/007
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A linearized voltage controlled amplifier (VCA) circuit uses the resistance of a gain control MOSFET to control amplifier gain in accordance with a DC gain control voltage. A gain control voltage is applied to the gain control MOSFET's gate through a gate input resistor that forms a voltage divider with a feedback resistor from the output of the amplifier. Since the VCA's output terminal is a low impedance node, the voltage divider network applies most of the gain control voltage to the gate of the gain control MOSFET. Conversely, a small fraction of the amplifier output signal is coupled to the gain control MOSFET's gate, to reduce distortion. The linearized VCA circuit is augmented by a gate drive correction circuit, through which the gain control voltage is coupled to the VCA's gain control MOSFET. The gate drive correction circuit is comprised of a difference amplifier and a compensating MOSFET that is matched with the gain control MOSFET of the VCA circuit for controlling its gate drive voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.