C2000 Type-2 Programmable Gain Amplifier Use Cases

Abstract

Type-2 programmable gain amplifier (PGA) module incorporates an operational amplifier (op-amp) with an internal adjustable gain that can be changed from 2V/V to 64V/V. Due to the PGA's high-input impedance, wide bandwidth, and low output impedance, the PGA offers a buffer operational mode that can present load isolation at the output of the buffer. Having fully differential and rail-to-rail inputs allow the PGA module to easily interface a wide range of input signals and fit them to the low-voltage domain of analog-to-digital converters (ADC). These features make the PGA module a high-performance analog front-end for various applications. This application note describes the functionality of the PGA module in all devices with a Type-2 PGA module, and how the module can be used for analog signal conditioning and acquisition in real-time control applications. For more information on peripheral types, see the C2000 Real-Time Control MCU Peripherals reference guide.

Trademarks

C2000™ is a trademark of Texas Instruments.

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1 Introduction

The integrated PGA helps to reduce cost and design effort for many control applications that traditionally require external, standalone amplifiers. On-chip integration makes sure the PGA is compatible with the downstream analog-to-digital converter (ADC) and comparator subsystem (CMPSS) modules. Software-selectable gain, filter settings, and different operational modes make the PGA adaptable to various performance needs. The PGA module provides a desired gain when an input signal has insufficient amplitude. The PGA module can be placed in front of a comparator or ADC to increase the signal's amplitude.

Type-1 and Type-2 PGAs offer adjustable gain values to amplify the input signal but have some key differences.

Operation modes: Type-1 PGA only supports non-inverting mode, while Type-2 PGA can support buffer, standalone, non-inverting, and subtracting operation modes. Please note that Type-2 PGA module can operate as a unity-gain amplifier to drive the input circuit of a successive approximation-register (SAR) ADC.
Gain range: Type-1 PGA only provides 3x to 24x voltage gain, while Type-2 PGA offers programmable gain values of 2x to 64x. The wide gain range makes Type-2 PGA a good choice for various applications.
Low-pass filtering: In Type-2 PGA, two different low-pass filters can be implemented using either the embedded filter resistor or the gain resistor. The gain resistor, in combination with an external capacitor, helps the more stable operation of the PGA modules.