What is the 1-Bit DAC topology for PWM or sigma delta DAC?

[tekno1]

Hello all,

What is the 1-Bit DAC topology for PWM or sigma delta DAC. Any practical input and suggestions about accuracy (linearity, SNR etc) will be appreciated.
Vdd=0 to 3.0V, DAC out range 0 to 2.5V (output is unipolar not differential).

Simply an inverter or a starved (current sources at supply terminals) inverter theoreticaly is 1-Bit DAC but matching errors of p-ch and n-ch would be a main problem. How this solved in real applications?

thanks in advance.

 

[jiesteve]

Re: 1 bit DAC topology

A 1-bit DAC is simply a comparator (diff amp with high open loop gain).

 

[tekno1]

Re: 1 bit DAC topology

@jiesteve

thanks for the answer. Theoretically yes it is a comparator with high gain but practically it does not work because slew rate limitation, rise fall time mismatch, propagation delay etc. There are practical circuits those provide very high linearity and circumvent error sources mentioned above. Practically people design 16 Bits DACs with 10-12 bits of linearity. One of my problem is I need single ended signal handling not differential one and my area budget terribly small.

I am after some practically feasible suggestions.

thanks again for your help, I have appreciated your efford and time.