In this section, the post-layout simulation results of each basic building block in the chip are introduced.

System Simulation

Figure 1: System Simulation

Mirrer OTA

In Figure 2, post-layout simulation result shows that the OTA has a gain of 75dB, a phase margin of 80 degrees, and a GBW of 33MHz under TT corner. The PVT simulation proves its stability.

Figure 2: Miller OTA Simulation

Triangle wave generator

Post-layout simulation result presents that the frequency is about 490kHz under PVT variation, as shown in Figure 3. Although it is slightly lower than expected 500kHz, it is stable and much higher than the maximum frequency of input audio signal, so it is acceptable. The difference comes from the comparator hysteresis, which is about 17mV for both of the comparators.

Figure 3: Triangle Wave Generator

The speaker used in the simulation was a Tymphany TC9FD18-08 3.5-inch full-range speaker. Commonly seen in modern home audio speakers. The circuit below was used to model the speaker in the simulation. It is important to use a realistic model for the speaker as the voice coil inductance can cause overshoots at the switching nodes.

Figure 4: Speaker Model

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