We present an accuracy improved hearing aid readout circuit using a gain-enhanced and OTA-free pseudo-PLL feedback technique. Compared with the conventional techniques, the technique replaces the typical oscillation approaches with a special pseudo-PLL feedback loop, which is able to partially amplify and directly convert the acoustic signal into the PWM signal without OTAs and comparators. Since the partially amplifying pseudo-PLL loop has the large open loop gain characteristic with the ultra low supply voltage, the accuracy of the large output signal should be maintained with the limited power dissipation. Fabricated with a 0.18 µm standard CMOS process, with the 1.2 V supply voltage and the input sine wave 1 KHz, the signal to noise and distortion rate (SNDR) achieves 55 dB@1 Vp-p output voltage with the bandwidth 20 kHz. Moreover, the circuit’s power consumption is 9 µW.
A precision curvature-compensated bandgap reference (BGR) is proposed and implemented using a standard 0.18-µm CMOS process. With a new and precise circuit configuration, the thermal nonlinearity of emitter-base voltages can be fully compensated, achieving an ultra-low temperature coefficient (TC) of 0.58 ppm/°C from −40 °C to 110 °C. The minimum required supply voltage is 1.2 V and the current consumption at 27 °C is 48 µA. At 27 °C, the line regulation performance is 0.015%/V with a supply voltage range of 1.2 V to 1.8 V.
This paper proposes a pulse-width modulation-based readout circuit for optical sensors which adopts adaptive frequency control technique to enhance input dynamic range of current sensing systems. The proposed readout circuit is designed and fabricated using a 65 nm CMOS process. The readout IC achieves 100 dB of dynamic range in current sensing system by adaptively controlling the frequency of operating clock.
For the purpose of developing a 4λ × 100-Gbit/s PAM4 10-km optical link, the dispersion tolerance through single mode fiber was experimentally investigated with a high-speed avalanche photodiode (APD) receiver. The power penalty was less than 1 dB over the LAN-WDM dispersion range.
In this letter, a novel broadband dual circularly polarized (CP) square slot antenna based on coplanar waveguide (CPW) feed is presented. Two orthogonal modified L-shaped monopoles fed by the CPW structure are designed to achieve dual circularly polarization. Through digging several rectangular notches while adding extra needle shaped tuning strip between two monopoles, wide impedance bandwidth (IMBW), wide axial ratio bandwidth (ARBW) and high port isolation are realized. Finally, in order to verify the analysis, a prototype is fabricated and measured. The measured available −10 dB IMBW of each port is 76% (from 1.8 GHz to 4.0 GHz), which covers the whole 3 dB ARBW of 67% (from 1.87 GHz to 3.75 GHz). Besides, the port isolation is below −25 dB and the cross polarization level is over −15 dB across the entire operating band, which proves the proposed antenna a good candidate for communication systems.
This paper presents a 6-bit 4 GS/s current-steering digital-to-analog converter (DAC) for wideband systems. The 4-2 segmented structure is adopted for glitch reduction, and a dynamic decoder is proposed to maintain low power consumption and small area. In order to improve the high-frequency dynamic linearity, the forward-bias technique is employed to reduce the device sizes, and a compact one-dimensional (1-D) current source unit is used to further minimize the parasitic capacitance. The DAC is fabricated in 40-nm low-leakage CMOS process and occupies the active area of 0.036 mm2. Over the entire Nyquist range, measurement results show a spurious free dynamic range (SFDR) of >39 dB at 2 GS/s sampling rate and >29 dB at 4 GS/s, respectively. The DAC consumes 28 mW power from 1.1 V supply voltage.
The Terahertz (THz) technology field is currently a popular scientific topic. In this paper, the transmission characteristics of two coupled planar transmission lines (microstrip-double slot and double microstrip-slot coupled lines) are investigated via odd-mode excitation and even-mode excitation in the THz band. Furthermore, we study the attenuation constant and the effective refractive index of the two transmission lines under investigation. We have compared the propagation characteristics of THz pulses on microstrip-lines and coplanar strip-lines; we find very good agreement between the observed results.