![Tda7293 parallel circuit layout](https://kumkoniak.com/101.jpg)
![tda7293 parallel circuit layout tda7293 parallel circuit layout](https://1.bp.blogspot.com/-_gc1tVJfIQc/U8q5Zf-csBI/AAAAAAAAG3I/C5Jqudec760/s1600/triple+amplifier+circuit+TDA7497S+pcb+layout.jpg)
The chip-amps were tested the same way but probably not according to a standard. I tested TDA7293 and some other chip-amps for use in composite amplifiers. Hence, stability of the power amplifier block needs to be ensured before trying to add an outer control-loop. As the outer loop is much slower than the regulation loop used for the inner element, the outer loop has no chance of compensating for an inner element that misbehaves. It is mandatory that the inner element is absolutely stable under all normal operational conditions. The higher bandwidth of the outer loop, the better suppression of distortion in the power amplifier output. The higher the bandwidth of the power amplifier, the higher we can leave the bandwidth of the controlling OP-AMP outer loop. Thus, we should use a power amplifier block with a bandwidth as high as possible.
![tda7293 parallel circuit layout tda7293 parallel circuit layout](https://4.bp.blogspot.com/--_4blIIceKw/TvoFMwl8jFI/AAAAAAAAE6Q/d2ElT4hcDPc/s1600/12-27-2011%2B18-44-27.jpg)
Phase-delay between input and output of the inner element is little significant seen from the outer loop and has less importance for the stability of the outer loop. The outer loop will see the inner element as a simple multiplication element between input and output of the inner element. When the inner element has a much higher bandwidth than the outer loop, the inner element has a simple transfer function seen in the operational range of the outer loop. The outer loop is the OP-AMP control loop.
![tda7293 parallel circuit layout tda7293 parallel circuit layout](https://image.dhgate.com/albu_198335428_00-1.0x0/f171-tda7293-parallel-555w-fever-amplifier.jpg)
The inner element in our case is the power amplifier block.
![tda7293 parallel circuit layout tda7293 parallel circuit layout](https://i.pinimg.com/736x/d6/85/8d/d6858df8981cba86ffb5b10d82a3596a--chips-october.jpg)
Further, if I am wrong it is possible to correct me before I go too far with useless ideas.Ī principle with nested loops is that the simple way to make the combination work is by keeping the bandwidth of an inner element much higher than the bandwidth of an outer loop. A few qualitative considerations that may help less experienced DIY’ers to understand what we aim to do.
![Tda7293 parallel circuit layout](https://kumkoniak.com/101.jpg)