Abstract
In this paper, a new digitally controlled linear-in-dB CMOS variable gain amplifier is proposed. The circuit employs the proposed novel approach in achieving a wide-range true-exponential transfer function e 2X using a traditional pseudo-exponential amplifier followed by a variable gain stage, to expand the output dynamic range. A single digitally controlled variable resistor is used to tune the circuit accordingly by controlling X with a digital word. The result is a digitally controlled data conversion that yields a new type of non-linear digital-to-analog converter. Finally, a 4-bit converter is implemented in a TSMC 0.18 μm CMOS technology and displays a gain from about −21 dB to 36 dB in steps of 3.89 dB with an output linear error in [−0.66,0.45] dB and a static power consumption of 2.34 mW.
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Purighalla, S., Maundy, B. 4-Bit Parallel-Input Exponential Digital-to-Analog Converter in CMOS 0.18 μm Technology. Circuits Syst Signal Process 31, 413–433 (2012). https://doi.org/10.1007/s00034-011-9314-9
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DOI: https://doi.org/10.1007/s00034-011-9314-9