A 0.2-V Three-Winding Transformer-Based DCO in 16-nm FinFET CMOS

Abstract

In this brief, we introduce a 3.2-4 GHz threewinding transformer-based class-F digitally controlled oscillator (DCO) with a DC-DC booster for energy harvesting applications. A π-model is adopted for this multi-turn transformer to analyze its impedance transformation and overall loop gain. The trifilar coil generates large passive voltage loop gain, allowing the DCO supply voltage of 0.2 V to be even lower than the threshold voltage of transistors without any performance degradation. Due to the gate/drain isolation as well as smaller voltage-dependent capacitance in advanced FinFET technology, this work achieves very low supply frequency pushing of 38 MHz/V. The switched capacitor placed at the tertiary winding can reach very fine resolution of 1.3 kHz due to the impedance transformations and source degeneration. The bias and control voltages of nearly zero power are generated with a switched-capacitor based DC-DC converter and a ring-based non-overlapped clock generator.

Exploring Speed Maximization of Frequency-to-Digital Conversion for Ultra-Low-Voltage VCO-Based ADCs

“…Despite the M 8 sleep transistor cutting off the power supplied to the standby-redundant PS blocks, the leakage power (10 nW per SA) is still significant. To mitigate the issue of for standby circuits, an on-chip switched-capacitor voltage doubler [13] for high-impedance loads is implemented in our ADC prototype to straightforwardly boost the V STBY bias to 420 mW, with the consequent power breakdown shown in Fig. 15(b).…”

“…While its operational speed was exponentially slowed down, the aforementioned subthreshold circuits provided a compelling solution for energy-constrained applications, such as biomedical and environmental monitoring, because the signals of interest hardly exceeded a few kHz. On the other hand, transformational advances in energy harvesting (EH) have produced a resurgence of general interest in expanding the ULV design space beyond ULP digital processors [9], [10], [11], [12], [13], [14], [15], as ambient energy harvesters can produce output voltages ranging from 50 mV to 200 mV [16]. To enable the widespread adoption of EH for a broader range of IoT applications, the achievable data throughput should therefore be improved by several orders-of-magnitude.…”

A 30-GHz Class-F Quadrature DCO Using Phase Shifts Between Drain–Gate–Source for Low Flicker Phase Noise and I/Q Exactness

“…4 In the proposed QDCO shown in Fig. 3(a), an additional source tank (L S , C S ) is added [68] (thus making it a three-coil transformer [68], [69], [70]) to each of the two class-F DCOs [59] to form "antiphase coupling" from one transistor's drain node to another transistor's (i.e., its antipodal) source node (by k SD ), thereby generating quadrature phases (like source-coupling in [44]). Specifically, the transconductor (−G m ) switching devices are reused as injecting devices, eliminating the significant contribution of flicker PN from the conventional injecting transistors (i.e., M 5 -M 8 in Fig.…”

“…In simulation, we observe that only V S,{IP/IN/QP/QN} waveforms include the coupling components from the other core, thus supporting our analysis. For more details on a three-winding resonator, we refer to[68].This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.…”

Three-Winding Transformer-Based 60-GHz DCO With −185.1-dB FoM in 40-nm CMOS

“…The voltages on the primary, secondary, and tertiary winding coils are expressed as V 1 , V 2 , and V 3 . The π -model employs an ideal transformer in the center with effective turn ratios of A and B [12]. Each winding has its leakage inductance, but the primary winding has a mutual inductance M 0 in parallel with the ideal transformer.…”