Analog Devices,inc.

Steven R Robinson

Janos Kovacs

Wyn T Palmer

An intrinsic R2R resistance ladder digital to analog converter (DAC) includes a plurality of matched semiconductor ladder switches, one in each of the R and 2R legs of the R2R ladder. The ON resistance of each semiconductor switch being matched to constitute the resistance ladder of the DAC; the ladder switches being operated in response to the digital signal input to the DAC; a reference circuit including a reference semiconductor switch matched with the ladder switches responsive to a reference current to generate a reference voltage; and a voltage follower circuit for monitoring the reference voltage and adjusting the current through the ladder switches to match the voltage at each ladder switch with the reference voltage for precisely fixing the DAC analog output current as a proportion of the reference current in dependence upon the operation of the ladder switches by the digital input signal.

Intrinsic R2R resistance ladder digital to analog converter

A hybrid analog/digital automatic gain control gain recovery system includes a variable gain amplifier (VGA) for receiving a variable amplitude input signal; a first AGC loop includes an analog to digital converter (DAC) for receiving the analog input signal and converting it to a digital signal; a digital gain error detection circuit for detecting variations of the digital signal in a first range and generating a digital error correction signal; and a digital to analog converter (DAC) for converting the digital error correction signal to a first analog correction signal; a second analog AGC loop includes an analog gain error detection circuit, responsive to variations in the output of the VGA in a second range greater than the first range for generating a second analog correction signal; and an integrator circuit responsive to the first and second analog correction signals for providing to the VGA a control signal to adjust the gain of the VGA to accommodate variations in the input signal amplitude.

Growing community of inventors

North Andover, MA, United States of America

Steven R Robinson