CLASS D AMPLIFIER

CLASS D AMPLIFIER

1. Class D Amplifiers Operation and Applications PRESENTED BY : A.G.PARANTHAMAN ASSISTANT PROFESSOR DEPARTMENT OF ECE KARPAGAM INSTITUTE OF TECHNOLOGY, COIMBATORE

2. Power Amplifier An amplifier is an electronic device used to increase the magnitude of voltage/current/power of an input signal . It takes in a weak electrical signal/waveform and reproduces a similar stronger waveform at the output by using an external power source. Depending on the changes it makes to the input signal, amplifiers are broadly classified into Current, Voltage and Power amplifiers.

3. CLASSES OF AUDIO AMPLIFIERS There are  many classes of audio amplifiers: A , B, AB, C, D, E, and F . These are classified into two different operating modes Linear and Switching .

4. Modes of Power Amplifiers Linear Mode Power Amplifiers – Class A, B, AB and  C have an output that is proportional to their input.  Less efficient Switching Amplifiers- Class D, E and F . More efficient

5. What is a Class D Audio Amplifier? A Class D audio amplifier is basically a switching amplifier or PWM amplifier . Class D amplifier is a switching amplifier and when it is in the “ ON ” state it will conduct current but have almost zero voltage across the switches, therefore no heat is dissipated due to power consumption . When it is in the “ OFF ” mode the supply voltage will be going across the MOSFETs, but due to no current flow, the switch is not consuming any power. 

6. Class D amplifier

7. Block Diagram of a Class D Amplifier

8. Stages of Class D amplifier PMW modulator Switching circuit Output low pass filter

9. PMW Modulator

10. A comparator has two inputs, namely Input A and Input B. When Input A is higher in voltage than Input B, the output of the comparator will go to its maximum positive voltage(+ Vcc ). When Input A is lower in voltage than Input B, the output of the comparator will go to its maximum negative voltage(- Vcc ).

11. Switching Circuit Provides enough power gain to drive the load Designed using MOSFETs Switching circuits should produce signals that do not overlap. Otherwise shoot through occurs The non-overlapping time is known as Dead time

12. We must keep the dead time as short as possible to maintain an accurate low-distortion output signal but must be long enough to maintain both MOSFETs from conducting at the same time A Schottky diode can be added in parallel to the drain and source of the MOSFET to reduce the losses through the MOSFET

13. Output Low Pass Filter Output filter attenuates and removes the harmonics of the switching signal frequency A 2 nd order Butterworth filter is desired so that we have a - 40 dB/Decade roll-off The range of cutoff frequencies is between 20 kHz to about 50 kHz

14. Applications Suitable for portable devices Television sets and home-theatre systems. High volume consumer electronics Headphone amplifiers Mobile technology Automotive

15. Best Class D Amplifiers For Home Audio

16. Best Class D Amplifiers For Home Audio S.M.S.L AD 18 Crown XLS 150 NAD D3045 Heaven 11 Billie Hegel H95 Bel Canto C5i Lyngdorf TDAI 1120 Lyngdorf SDA 2400 Bel Canto REF600M Legacy Audio I-V2 Bel Canto Black EX Integrated

17. THANK YOU