| Class "Bridge" |
| Bridge Mode, is two class AB
amplifiers, one non inverter an non inverter, that takes advantage
of the fact that speakers loads can be driven differentially, using
separate amplifiers to drive the speaker terminals with opposite
polarity waveforms. Bridging is a ideal amplifier, results in an
effective doubling the voltage swing yielding four times the
single-ended power output. |
| Advantages: |
| 1) Provides high output power levels
using lower voltage components. |
| 2) Because no current flow through
ground, distortion is low. |
| 3) Symmetrically loads the power
supply by virtue of the fact that both outputs (Usually L & R
are driven 180° out of phase, therefore the VCC rails are not being
driven by the same channel at the same time |
| 4) Provides some common mode noise
cancellation, especially in amps that use PWM power supplies which
radiated EMI. |
| 5) excellent for drive balanced
outputs, e.g.. XLR transmission lines in audio mixer and record
studios. |
| Disadvantages: |
| 1) Increased circuit cost |
| 2) Increase circuit complexity |
| 3) Inability to ground speaker outputs |
| 4) Circuit outputs must be always floating |
| Conclusions and
comments: |
| Bridge topology is the most accepted
in car audio due to high power output and can be connected in stereo
or bridged. BTL chips amps (Bridged Transformer Less) use available
+12V single power supply for simplicity in designs requiring power
levels of 5 to 50 watts. |
