Low‐temperature‐dependence CMOS linear driver with serial peripheral interface for 64‐Gbaud ultra‐low power coherent optical transmitters

Abstract

The authors used 65-nm CMOS technology to develop a linear four-channel driver IC with low temperature dependence and ultralow power dissipation for 64-Gbaud coherent optical transmitters. The driver showed more than a 48-GHz 3-dB electrical bandwidth and less than 1-W power consumption in four-channel operation. By employing a circuit that suppresses the temperature dependence, they achieved 3-dB electrical bandwidth variation of 3.0 GHz and the gain variation of 1.5 dB under the −5 to 75°C and ±5% supply voltage variation conditions. The CMOS driver has all the necessary functions for a high-bandwidth coherent driver modulator such as a gain control, peaking control, peak detection and temperature monitoring, all of which functions can be controlled by a serial peripheral interface. A fabricated sub-assembly consisting of the CMOS driver and an InP modulator showed a 48-GHz 3-dB electro-optic bandwidth.

500-Gb/s/λ Operation of Ultra-Low Power and Low-Temperature-Dependence InP-Based High-Bandwidth Coherent Driver Modulator

“…The total power consumption of the HB-CDM includes the power of the driver IC, the TEC, termination resistors, and the modulator bias. The power of the CMOS driver is less than 1 W under the −5°C to 85°C case temperature condition [15], which is less than half that of the commercial SiGe driver (2 W) for 64 Gbaud. The power reduction of the driver is also effective in decreasing heat flow into the TEC and reducing the consumed power of the TEC.…”

“…5(b). This indicates that the resistors and circuit for reducing temperature variation of the driver characteristics [15] is effective. Fig.…”

“…To suppress the temperature-related variation of the bandwidth, we used load resistors with a low temperature dependence. From the functional point of view, a serial peripheral interface (SPI) was integrated in the driver [15]. Via the SPI, we can control the gain and peaking level and read the peak amplitude and temperature.…”

“…For more information, see https://creativecommons.org/licenses/by/4.0/ linear modulator driver for an InP modulator in 65-nm CMOS [13]. With its stacked current mode architecture [14] and an open-drain structure, our CMOS driver achieves more than a 48-GHz 3-dB electrical bandwidth and consumes less than 1 W in four-channel operation [15]. Moreover, we compensate for temperature-dependent variation of the bandwidth and gain by utilizing a power supply circuit that contains two types of resistors with different temperature gradients and a voltage regulator circuit [15].…”

“…With its stacked current mode architecture [14] and an open-drain structure, our CMOS driver achieves more than a 48-GHz 3-dB electrical bandwidth and consumes less than 1 W in four-channel operation [15]. Moreover, we compensate for temperature-dependent variation of the bandwidth and gain by utilizing a power supply circuit that contains two types of resistors with different temperature gradients and a voltage regulator circuit [15]. By integrating the low-power CMOS driver and the low-V π InP modulator in one package so that the distance between chip edges was less than 50 µm and optimizing the operating temperature of the modulator, the HB-CDM with consumes 2.5 W or less at case temperatures from −5 to 75°C and less than 2.8 W from −5 to 85°C.…”