A digital temperature compensated crystal oscillator using a temperature adaptive capacitor array

We propose a new capacitor array scheme that we call a temperature adaptive capacitor array (TACA) and use it to achieve complete digital trimming of the TCXO at 20 MHz with 0.3 ppm trimming accuracy. The TACA scheme guarantees monotonicity and saves silicon area at the same time. About 10 % reduction in array layout area and about 14 % reduction in the pre-decoding logic area are reported.