A 0.008-mm² area-optimized thermal-diffusivity-based temperature sensor in 160-nm CMOS for SoC thermal monitoring

Abstract

An array of temperature sensors based on the temperature-dependent thermal diffusivity of bulk silicon has been realized in a standard 160-nm CMOS process. The sensors achieve an inaccuracy of ±2.4 °C (3σ) from -40 to 125 °C with no trimming and ±0.65 °C (3σ) with a one temperature trim. Each sensor occupies 0.008 mm 2 , and achieves a resolution of 0.21 °C (rms) at 1 kSa/s. This combination of accuracy, speed, and small size makes such sensors well suited for thermal monitoring in microprocessors and other systems-on-chip.

Analysis and Design of VCO-Based Phase-Domain $\Sigma \Delta $ Modulators

“…14 (b), the error then reduces to less than 2 m°. A reduction in the phase range can be easily achieved in multi-bit PDΣΔMs or two-step PDΣΔMs [7], thus making such architectures robust to the non-linearity of typical VCO's, which show third-harmonic distortion ranging from -40 to -60 dB.It must be again highlighted that the high tolerance to distortion of the proposed read-out is an inherent property of phase-domain read-outs. Even a large distortion in the amplitude domain at the system input does not significantly affect the phase of the signal, which is the parameter carrying the information to be detected and converted.…”

“…An S bit up/down counter is used to combine demodulation and integration, while an M bit register acts as the quantizer. The quantizer sampling clock (FS) is typically chosen at the same frequency as FDEM [7].…”

“…This results in a DC component proportional to their phase difference, as well as higher order components. The multiplier's output is applied to a loop filter, which in the case of a 1 st -order modulator is an integrator [7]. The loop filter drives an M bit quantizer, which, in turn, drives an M bit phase DAC that adjusts the phase of VDEM.…”

Compact Thermal-Diffusivity-Based Temperature Sensors in 40-nm CMOS for SoC Thermal Monitoring

“…For a single-bit modulator, ΦDAC switches between the two phase references, Φ0 and Φ1. FDRIVE and phase DAC outputs can be generated by a digital block, which is driven by an accurate high frequency clock (FSYNC) [12]. However, such PDΣΔMs require large integration capacitors and high-gain amplifiers [12], which in turn occupy significant area.…”

“…However, the reported smart sensor was too large (0.18 mm 2 ) and too slow (1 Sa/s) for thermal monitoring applications. By employing more compact electronics, much smaller smart TD sensors with areas of 8000 μm 2 [12], and even 2800 μm 2 [13], have been reported. However, these sensors were also implemented in a relatively mature 0.16-μm CMOS process.…”