A very compact 1MS/s Nyquist-rate A/D-converter with 12 effective bits

Abstract

Abstract-We present a very compact analog-to-digital convertor (ADC) for use as a standard cell. To achieve an inherent accuracy of at least 12-bits without trimming or calibration, extended counting A/D-conversion is used. Here, the circuit performs a conversion by passing through two modes of operation: first it works as a 1st-order incremental convertor and then it is reconfigured to operate as a conventional algorithmic converter. This way, we obtain a Nyquist-rate converter that requires only 1 operational amplifier and achieves 12-bit accuracy performance in 13 clock cycles with 9 bit capacitor matching. The circuit is designed in 0.18 µm CMOS with a thick oxide option. The resulting analog core occupies a chip area of only 0.011 mm 2 and the complete digital control and reconstruction logic (including additional test features and storage registers) is 0.02 mm 2 . The analog blocks of the circuit consume 1.2mW and the digital 0.4mW. At a sample rate of 1 MS/s, the peak SNDR is 74.5dB and the dynamic range is 78dB, constant over the Nyquist band. The worst-case integral non-lineairity (INL) is within ±0.55 LSB.

A Low-Noise Instrumentation Amplifier With Built-in Anti-Aliasing for Hall Sensors

“…The output V out is digitized by a Nyquist-rate extendedcounting ADC [39]- [42] to a 14-bit word. The ADC is the exact same design as in [42] and so details on its operation and measurement results can be consulted there. The ADC is clocked at 10×f s (10 MHz), performs N = 5 counting steps and 10 cyclic conversions in order to produce a sample every 1/f s = 1 µs.…”

Single Op-Amp algorithmic converter and its offset and mismatch compensation

“…The latter case is used in [2]: the algorithmic architecture is configured as a first order incremental and after a number of accumulation of the input, the scheme becomes algorithmic. The result is that the number of bit determined in the preliminary phase increases the final resolution.…”

“…Indeed, experimental results of a previous published solution [2] showed that it is possible to achieve 12-bit resolution relying on the accuracy normally granted by available technology.…”