학술논문
A VCO-Based ADC With Inherent Mixing Capability and Local Oscillator Suppression in 55-nm CMOS
Document Type
Periodical
Author
Source
IEEE Transactions on Circuits and Systems II: Express Briefs IEEE Trans. Circuits Syst. II Circuits and Systems II: Express Briefs, IEEE Transactions on. 70(9):3338-3342 Sep, 2023
Subject
Language
ISSN
1549-7747
1558-3791
1558-3791
Abstract
This brief introduces a new circuit that can be used as a mixer and as a VCO-ADC simultaneously. The power supply nodes of the inverters in a ring oscillator are sorted in two sets, and connected to two different input signals. We prove mathematically that the oscillator frequency of such configuration reacts to the product of the two analog inputs. Therefore, the ring oscillator can be used as an ADC to directly digitize the low pass down converted component. A first system-level approach is made to minimize the non desired beat components by a proper number of taps in the ring oscillator. To confirm the concept of the Mixer VCO-ADC and its performance, a 55nm CMOS chip has been designed and fabricated. Measurements show a SNDR of 51.3 dB in a 100 kHz bandwidth in the down converted signal from a 1.001 MHz input signal mixed with a 1 MHz local oscillator.