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1 Introduction
Freescale's Kinetis microcontrollers integrate a 16-bit analog-
to-digital converter (ADC16) with built-in programmable gain
amplifier (PGA), which is capable to operate in several modes.
The Programmable Gain Amplifier (PGA) is designed to
increase the dynamic range by amplifying low-amplitude
signals before they are fed to the 16-bit ADC.
1.1 Abstract
Whenever a gain stage is included in the converter path, the
Signal to Noise Ratio (SNR) will go down. This effect occurs
because the PGA induces noise into the system. Therefore,
question may arise why would an application include PGA on
the system?
The main reason to include a PGA stage before an ADC
conversion is to increase the dynamic range. Dynamic range
indicates the minimum resolvable step size and the ratio
between the largest and smallest possible inputs. Resolution is
the number of bits in the result, and is often confused with
dynamic range.
Freescale Semiconductor
Document Number:AN4568
Application Note
Rev. 0, 09/2012
Understanding the 16-bit ADC PGA
in Kinetis K series
by: Martin Mienkina, Han Lin, and Alejandra Guzman
Automotive and Industrial Solutions Group
© 2012 Freescale Semiconductor, Inc.
Contents
1 Introduction................................................................1
2 Kinetis PGA integration............................................2
3 PGA dynamic input examples...................................5
4 16-bit ADC measurement use-case ..........................7
5 Conclusion.................................................................9
6 References.................................................................9
