Variable gain amplifier utilizing positive feedback and time-domain calibration

Physical Sciences : Electrical

Available for licensing


  • Nan Sun, Ph.D. , Electrical & Computer Engineering
  • Miguel Gandara , University of Texas at Austin

Background/unmet need

In discrete-time systems, including ADCs, a voltage amplifier is necessary to increase the signal swing for further processing. Traditional precision amplification techniques, including closed-loop amplifiers, become less viable in nanometer-scale processes due to reduced transistor intrinsic gain. Additionally, these devices generally consume static power, which becomes a larger percentage of overall power consumption as dynamic power decreases with further device scaling.

Recently, interest has grown in the usage of dynamic amplifiers in discrete-time systems. These amplifiers consume no static power, allowing for increased power efficiency as devices scale. Additionally, these devices are generally constructed in open-loop configurations, which greatly reduce the gain requirements for the amplifier. These dynamic amplifiers suffer from their own limitations, including increased sensitivity to process variation and inaccurate gain.

Invention Description

Researchers at The University of Texas at Austin have developed a technology which uses a combination of integration and positive feedback regeneration in order to achieve high-speed amplification. Noise and linearity can be traded off for increased speed by adjusting the lengths of the integration and amplification phases. Additionally, the invention overcomes the issues of process sensitivity and inaccurate gain by implementing a time-domain-based calibration technique. The total amplification time can be tuned in the background to provide a precise gain across PVT variations.


  • Positive feedback amplification. This increases the speed and provides a gain that is proportional to amplification time.
  • Simple mixed-signal calibration scheme. A tunable delay line is used to control the amplification time, and thus the gain. Additionally, timing resolution gets better with device scaling, so gain precision increases with device scaling. This calibration can also be used to dynamically change the gain based on run-time requirements.


  • High-speed discrete-time amplification
  • Variable gain by adjusting amplification time
  • No DC power consumption

Market potential/applications

 Discrete-time signal processing applications, including pipelined ADCs.

Development Stage

Proof of concept

IP Status

  • 1 U.S. patent application filed