I want to drive a small speaker (4 Ohm, 1..3 W) from an FPGA, in a battery-powered gadget. The supply voltage is 3.7V from a LiPo. Small integrated class D amplifiers like the PAM8302A are an obvious choice to do this.
But my audio already comes out of the FPGA as a PWM signal, so it seems a bit silly to low-pass filter it, only to chop it up into PWM again in the amplifier. And, more importantly, I am concerned about beat frequencies between the amp's PWM frequency and any residual PWM carrier from the FPGA output. Hence would prefer to drive the speaker directly with the amplified PWM signal from the FPGA.
Is there a small-and-simple integrated H-bridge which you would recommend for this, or a dedicated "digital speaker driver" IC? Or can you think of reasons why this is a bad idea? Thanks!