Design Simulation Results

TINA simulations are run originally without the voltage divider as part of the circuit. This allows for insight into the optimized value of R_ZCO. Later, a voltage divider is added to the circuit to further optimize crossover distortion.

A 5V_P square wave is applied to the input of the circuit. The output response provides insight into the current driving the load when the MOSFETs are turned off. Selecting R_ZCO resistors that are too low (100 Ω, 499 Ω) result in excessive current flow (labelled I_ZCO) from the output of the amplifier. Here, 1 kΩ was chosen for R_ZCO as it adds 5.14mA of current to the circuit, as opposed to the 10.29mA of current consumption with the 499 Ω resistor (see the figure above). Furthermore, the noise difference between the 499Ω resistor and the 1kohm resistor is minimal, making 1 kΩ a suitable choice for R_ZCO. A larger resistor can be used but will add additional noise to the circuit.

Looking at V_LOAD when R_ZCO = 1kΩ, there is still distortion. This distortion is due to the NMOS FET turning on. Adding a voltage divider to the circuit allows for a controlled V_GS that is continuously applied to the gate of the MOSFET.

OPA591 Discrete Output Current Boost Circuit Transient Simulation Results and OPA591 Discrete Output Current Boost Circuit DC Sweep Simulation Results show the simulated design results for the completed circuit. The distortion on the output has been minimized after adding a voltage divider to the gate of the MOSFET.

The post processor in TINA is used to calculate the average output power of the circuit (seen at node VOUT), using the same calculation as seen above in Equation 8.

The DC sweep analysis in TINA shows the linear relationship between the input voltage and the output current.