Re: differential amplifier can suppress even order harmonics
For any amplifier:
Vo=a0+a1Vi+a2*(Vi^2)+a3*(Vi^3)+a4*(Vi^4)+a5*(Vi^5)+............
where a2,a4,a6,....... are the even harmonics coefficients
while a3,a5,a6,........ are the odd harmonics coefficients
Since the sign of the input will not appear in the even harmonics terms as it is always raised to the power of an even number, thus at the two outputs of the differential amplifier the even harmonics are the same(assuming perfect matching) and thus when the two output are subtracted(differential output) the even harmonics on both sides will cancel each other.