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A Novel Quadrature-Phase Sampling Technique for Filterless, Low-Complexity, High-Alias-Suppression in VCO-ADCs
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DOI：10.1109/OJCAS.2025.3631878.png)
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Abstract
En 中文
Next-generation LiDAR systems demand unprecedented resolution, requiring wide signal bandwidth and high-density pixel arrays that constrain each pixel circuit to <= 0.01 mm(2). This limits the complexity and power available for anti-aliasing filtering in the receiver front-end, even though strong attenuation of interference and alias noise is critical to preserve signal fidelity. Voltage-controlled oscillator (VCO)-based analog-to-digital converters (ADCs) offer inherent anti-aliasing through spectral shaping, but for bandwidths >= 50 MHz, the attenuation is insufficient, necessitating dedicated analog filters that undermine area and power. To resolve this, we propose a novel sampling technique for VCO-ADCs, employing quadrature clocks instead of conventional clocking. The resulting output spectrum exhibits a quasi-sinc(3)-shaped response that improves alias attenuation by similar to 10 dB to 80 dB at 50 MHz bandwidth-the highest reported to date-eliminating the need for analog filters. We derive an analytical expression for this response, accounting for non-idealities and offering insight into the parameters governing the shaping behavior. The technique is demonstrated with a proposed filterless, low-complexity VCO-ADC circuit in CMOS 65 nm, occupying just 0.0017 mm(2)-43% smaller than the state-of-the-art-and dissipating only 0.42 mW at 2 GHz sampling in simulation. Benchmarking shows a figure-of-merit of 56 fJ/conversion-step, similar to 1.1x better than the best reported design.
Keywords:
Circuits
Filtering
Filters
Finite impulse response filters
Oscillators
Voltage-controlled oscillators
Phase noise
System-on-chip
Circuits and systems
Integrated circuits
Solid-state light detection and ranging (LiDAR)
anti-aliasing
sampling
voltage-controlled oscillation (VCO)
analog-to-digital converter (ADC)
VCO-based ADC
spectral shaping
Journal
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2.4
Papers:
4.5K
Citations:
387
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Cited Papers