Patent ID: 6693491
Filing Date: 2004-02-17
Classification: H03G

Abstract:
A control circuit for controlling a level of a signal and transmitting the signal to a first amplifier, comprising:a first R-2R resistor network for receiving the signal, the first R-2R resistor network having a first plurality of resistor nodes; a first parallel resistor network for receiving the signal, having a plurality of parallel resistors with different values and a second plurality of resistor nodes, the first of the plurality of parallel resistors having a value R corresponding to the value of R in the first R-2R resistor network, and each subsequent resistor in the plurality having a value of one-half times the value of the preceding resistor; a first plurality of switches coupled to the first plurality of resistor nodes for alternately connecting each of the first plurality of resistor nodes to one of a plurality of low impedance nodes and a first low impedance input node associated with the first amplifier; a second plurality of switches coupled to the second plurality of resistor nodes for alternately connecting each of the second plurality of resistor nodes to one of a plurality of low impedance nodes and a first low impedance input node associated with the first amplifier; and switch control circuitry for selectively controlling the first plurality of switches and the second plurality of switches to transmit the signal to the first low impedance input node, wherein the switch control circuitry is configured to connect only one of the first and second pluralities of resistor nodes to the first low impedance input node at a time.