This article presents low-power circuit design techniques to achieve third-order noise shaping by employing multiple stages of passive switched-capacitor gain-boosted integrator and a passive switched-capacitor integrator. First integrator is a passive switched-capacitor for higher linearity. Second integrator is a three-stage passive switched-capacitor gain-boosted integrator to provide passive gain to the loop filter as well as the second DAC feedback. While the third integrator is a two-stage passive switched-capacitor gain-boosted integrator to provide passive gain as well as third DAC feedback for higher stability. Multiple lower stages of passive switched-capacitor gain-boosted integrators employed to enhance the noise shaping order of the modulator and suppress the parasitic effect. The preamplifier is the only active block, while the dynamic comparator used as single-bit quantiser. The complete transistor level with thermal noise simulation can achieve 84 dB of dynamic range (DR), 78.2 dB signal-to-noise-plus-distortion ratio (SNDR), and 78.5 dB signal-to-noise ratio (SNR) for 500 Hz signal bandwidth. It can also achieve signal-to-spurious-free dynamic range (SFDR) of 78.2 dB with estimated power consumption of 220 nW at 1 V supply voltage in SMIC 28 nm CMOS Technology. Finally, it can achieve state-of-the-art Walden Figure-of-Merit (FoM W) of 33 fJ/Conv-Step and Schreier FoM S of 171.2 dB.

The performance of a wideband receiver is highly dependent on the performance of the analogue-to-digital converter (ADC) used. Such applications require ADCs to operate at ultra-high speeds with high accuracy for inputs ranging from 40 MHz-1 GHz. Conventional solutions either use filters and mixers to extract the frequency of interest and convert it using a low-speed ADC or use a single ultra-high-speed flash converter. Both of these solutions consume ultra-high power and require complex circuitry, which expands exponentially with the converter resolution. In this work, a 12 bit 3.072 GS/s time-interleaved pipeline ADC is proposed. In total, 32 pipeline ADCs, each with a sampling rate of 96 MS/s, are interleaved in the time domain to achieve an overall sampling rate of 3.072 GS/s. In addition to the potential energy-saving capabilities of a time-interleaving structure, the circuit adopts amplifier sharing in sample-and-hold circuits, further improving the power efficiency. To account for interleaving mismatch, the circuit uses a pure background calibration technique, maintaining the system linearity and spectral efficiency. The proposed design achieves signal-to-noise-and-distortion ratio of 53.65 dB and spurious-free dynamic range (SFDR) of 69.04 dB while consuming 820 mW of power at a 1.2 V supply, resulting in a figure-of-merit of 0.67 pJ/conv-step.