• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.15 no.5
• /
• pp.335-342
• /
• 2022

In this paper, a single-bit 3rd-order feedforward delta sigma modulator is proposed for audio applications. The proposed modulator is based on a class-C inverter for low voltage and power applications. For the high-precision requirement, the class-C inverter with regulated cascode structure increases its DC gain and acts as a low-voltage subthreshold amplifier. The proposed Class-C inverter-based modulator is designed and simulated in 180-nm CMOS process. With no performance loss and a low supply voltage compatibility, the proposed class-C inverter-based switched-capacitor modulator achieves high power efficiency. This design achieves an signal-to-noise-and-distortion ratio (SNDR) of 93.9 dB, an signal-to-noise ratio (SNR) of 108 dB, an spurious-free dynamic range (SFDR) of 102 dB, and a dynamic range (DR) of 102 dB at a signal bandwidth of 20 kHz and a sampling frequency of 4 MHz, while only using 280 μW of power consumption from a 0.8-V power supply.

• Korean Journal of Optics and Photonics
• /
• v.34 no.4
• /
• pp.151-156
• /
• 2023

We propose to implement cost-effectively a high-speed short-haul interconnect by transmitting a 200-Gb/s/λ two-channel optical time-division-multiplexed signal generated by a carrier-suppressed optical pulse, which improves the robustness of the multiplexed signal to chromatic dispersion. The multiplexed 200-Gb/s signal is generated in the transmitter by combining two 100-Gb/s 4-level pulse-amplitude-modulated signals (generated using the optical pulse and two Mach-Zehnder modulators). After the signal is transmitted over a fiber, it is amplified by a semiconductor optical amplifier and detected by a photodiode. The amplified spontaneous emission noise is eliminated by an optical band-pass filter. The transmitted signal is reconstructed by a 2 × 2 multiple-input multiple-output equalizer, which compensates for crosstalk. Due to the use of the carrier-suppressed optical pulse, the 200-Gb/s signal can be transmitted over fiber with a chromatic dispersion of 40 ps/nm.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.5 s.347
• /
• pp.59-67
• /
• 2006

We demonstrate bidirectional long-reach 35-channel dense wavelength division multiplexing-passive optical network(DWDM-PON) based on wavelength-locked Fabry-Perot laser diodes (F-P LDs). The mode control of F-P LD enhances output power at decreased the required injection power. We show packet-loss-free transmission in all 70 channels at 125 Mb/s per channel line rate through 70 km of single mode fiber without optical amplifier The DWDM-PON can consolidate a metro network into an access network by bypassing the central offices within its reach. The proposed DWDM-PON can accommodate about 80 subscribers with an EDFA-based broadband light source. Further expansion up to 100 subscribers is possible with a semiconductor-based BLS.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.37 no.1
• /
• pp.40-48
• /
• 2000

1A novel bipolar linear transconductor and its application to operational transconductance amplifier(OTA) for low-voltage low-power signal processing is proposed. The transconductor consists of a npn differential-pair with emitter degeneration resistor and a pnp differential-pair connected to the npn differential-pair in cascade. The bias current of the pnp differential-pair is used with the output current of the npn differential-pair for wide linearity and temperature stability. The OTA consists of the linear transconductor and a translinear current cell followed by three current mirrors. The proposed transconductor has superior linearity and low-voltage low-power characteristics when compared with the conventional transconductor. The experimental results show that the transconductor with transconductance of 50 ${\mu}S$ has a linearity error of less than ${\pm}$0.06% over an input voltage range from -2V to +2V at supply voltage ${\pm}$3V. Power dissipation of the transconductor was 2.44 mW. A prototype OTA with a transconductance of 25 ${\mu}S$ has been built with bipolar transistor array. The linearity of the OTA was same as the proposed transconductor. The OTA circuit also exhibits a transconductance that is linearly dependent on a bias current varying over four decades with a sensitivity of 0.5 S/A.