Specifications
Application Report
SNAA058B–July 2008–Revised May 2013
AN-1850 LME49830TB Ultra-High Fidelity High Power
Amplifier Reference Design
.....................................................................................................................................................
ABSTRACT
This application report discusses the design and use of the LME ultra-high fidelity power amplifier input
stage ICs (drivers).
Contents
1 Introduction .................................................................................................................. 3
2 Overview ..................................................................................................................... 3
3 Operational Details ......................................................................................................... 4
3.1 Output Stage Power Dissipation ................................................................................. 6
4 PCB Connections ........................................................................................................... 8
4.1 Input Connections .................................................................................................. 8
4.2 Output Connections ................................................................................................ 8
4.3 Power Supply Connections ....................................................................................... 9
4.4 GND Connection Optimization ................................................................................... 9
4.5 Mute Function ..................................................................................................... 10
4.6 Gain and Frequency Response ................................................................................ 10
5 Output Stage Biasing ..................................................................................................... 11
5.1 V
BE
Multiplier ....................................................................................................... 12
5.2 Bias Stability ...................................................................................................... 17
5.3 Biasing Procedure ................................................................................................ 19
6 Compensation .............................................................................................................. 19
6.1 Single-Pole Compensation ...................................................................................... 19
6.2 Two-Pole Compensation ........................................................................................ 21
7 Performance Graphs (±60V) ............................................................................................. 22
8 Board Layer Views ........................................................................................................ 23
9 Bill of Materials ............................................................................................................. 26
List of Figures
1 Simple Power Amplifier Schematic ....................................................................................... 3
2 Source-Follower Output Stage ............................................................................................ 4
3 LME49830 EF125WT1 FET PCB Amplifier Schematic ................................................................ 5
4 Amplifier Module Test Setup GND Connections........................................................................ 9
5 Mute Circuit Reference Voltage ......................................................................................... 10
6 Gain And Low Frequency Response ................................................................................... 11
7 Output Stage DC Biasing V
BE
Multiplier Circuit ........................................................................ 12
8 THD+N Versus Frequency Versus Bias Current ...................................................................... 14
9 100mA Bias Current Distortion Residual ............................................................................... 14
10 100mA Bias Current Output FFT........................................................................................ 15
11 250mA Bias Current Distortion Residual ............................................................................... 15
12 250mA Bias Current Output FFT........................................................................................ 16
13 1A Bias Current Distortion Residual .................................................................................... 16
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SNAA058B–July 2008–Revised May 2013 AN-1850 LME49830TB Ultra-High Fidelity High-Power Amplifier Reference
Design
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