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A photoreceiver consisting of indium phosphide (InP) balanced photodiodes (PD) on Si $_3$ N $_4$ waveguides and a transimpedance amplifier (TIA) fabricated in a silicon germanium (SiGe) BiCMOS process is demonstrated. The InP PDs, heterogeneously integrated on a silicon substrate, achieve external (internal) responsivities of 0.75 (0.9) A/W, bandwidths of 4 GHz, and common mode rejection ratios (CMRR) of greater than 40 dB when illuminated differentially. The TIA achieves 74 dB $\bf \Omega$ of transimpedance gain with a 1 dB peak, a bandwidth of 3 GHz, and a low equivalent input noise current density of 7.2 pA/ $\sqrt{Hz}$ when loaded with a C $_{PD}$ of 380 fF. The full photoreceiver achieves high conversion gain of more than 2 kV/W up through 2 GHz, and a low NEP of 8 pW/ $\sqrt{Hz}$ up through 1.6 GHz. The photoreceiver optical CMRR is measured to be 36 dB.

High-power $V$ -band-to- $G$ -band (50–220 GHz) photonically driven electromagnetic emitters, composed of frequency-independent (FI) antennas and charge-compensated modified unitraveling carrier photodiodes (CC-MUTC PDs), are demonstrated in this article. The designed and fabricated PDs achieve a responsivity of 0.2 A/W and are able to provide up to 12-dBm output power. The impedances of the PD and the FI antennas (the sinuous antenna, the spiral antenna, and the log-periodic antenna) are characterized, showing that different antennas could be selected to provide either highest radiated power or widest bandwidth depending on applications. The measurement results indicate that the integrated emitter with the sinuous antenna and the 8- $\mu \mathrm {m}$ PD achieves a record-high broadside effective isotropic radiated power (EIRP) of 20 dBm with an optical-to-terahertz (THz) power conversion efficiency of 15.7% while maintaining EIRP greater than 0 dBm up through 115 GHz of bandwidth (50–165 GHz). The emitter with the spiral antenna and the 5- $\mu \mathrm {m}$ PD provides a wide 3-dB bandwidth of 34 GHz with a maximum EIRP of 8.8 dBm. These high-power wideband emitters can be used for wireless communications, millimeter-wave (mm-wave) and sub-THz imaging, and radar systems.

This paper describes a highly-integrated, supply-robust, event-driven wakeup receiver achieving

A photoreceiver with balanced SiN waveguide photodetectors and BiCMOS transimpedance amplifier is proposed, achieving a high conversion gain of greater than 2 kV/W up through 2 GHz, and a low in-band NEP of 8 pW/^Hz.

A planar circuit structure, which is based on three cascaded pairs of coupled lines, an open stub, and an isolation resistor, is proposed in this paper to design a compact dual-band balun with high isolation. This circuit features equal power division with out of phase, all ports matching, high isolation between two outputs, compact structure, and inherent impedance transformation. The closedform design equations are derived based on the traditional transmission-line theory and even-(odd-) mode analysis. A practical dual- band balun, which operates at 0.9/1.8GHz, is designed and fabricated to validate the function of equal power division with out of phase and high isolation between two outputs. The consistency between the simulated and measured results verify the design theory.

This study presents a novel planar coupled-line directional coupler with tunable both power division ratio and operating frequency, which is achieved using microstrip technology for the first time. Its tunability of the operating frequency and the power division ratio, or coupling ratio, can be independently controlled by the bias voltages. Moreover, it can simultaneously maintain perfect port match and isolation. On the basis of the even–odd mode analysis method, both the closed-form analytical equations and parameter discussions are provided to facilitate the practical design. An experimental prototype of the tunable coupler is simulated, fabricated, and measured to demonstrate how it works. The measured results indicate that power division ratio can vary from 0.35 (9 dB) to 0.71 (3 dB) when operating frequency ranges from 0.55 to 1.48 GHz (91.63%) while power division ratio varies from 0.35 (9 dB) to 1 (0 dB) when operating frequency is fixed at 1 GHz, which validated the reliability of the proposed model.

In this paper, a wideband high-power photonically-driven integrated electromagnetic emitter is proposed with operation from W-band through G-band (75 GHz to 220 GHz). The wideband and high-power behaviors are achieved by integrating a high-power charge-compensated modified unitravelling carrier (CC-MUTC) photodiode (PD) with a high-directivity two-arm sinuous antenna. The PD with a diameter of $5 \mu \mathrm{m}$ achieves a responsivity of 0.2 A/W and a 3-dB bandwidth of 120 GHz. The measurement results indicate that the emitter provides a high effective isotropic radiated power (EIRP) between 75 GHz to 210 GHz, achieving a maximum EIRP of 8.8 dBm at 130 GHz.

In this paper, a novel coupled-line tunable Wilkinson power divider with perfect port match and isolation in a continuously tunable passband is presented. The proposed tunable power divider consists of an isolation resistor, two coupled lines, and two types of varactors. By providing these varactors with suitable bias voltages, the operating frequency of the proposed power divider can be flexibly changed as desired. Meanwhile, perfect port match and isolation are maintained at all tunable operating frequencies. After applying the even-odd mode analysis method, the closed-form equations of the design parameters are derived to illuminate the effects on the minimum and maximum operating frequencies. These equations exhibit that the proposed power divider has a wide frequency tuning range and a high tunability (more than 110% in ideal conditions). Owing to the limitation of manufacturing process, a microstrip power divider with a tunable frequency of 0.54–1.41 GHz (89.23%) is designed and simulated based on the provided closed-form equations. The measured results show a frequency tuning range from 0.56 to 1.39 GHz (85.13%) with a more than 20-dB return loss and isolation in the entire tuning range, agreeing well with the simulation results.

A planar asymmetrical miniaturized circuit based on composite left- and right-handed transmission lines (CLRHTLs) is proposed to design a new balanced-to-single-ended (BTSE) power divider (PD) in this letter. The CLRHTLs are used to realize circuit miniaturization and positive-phase response. Conversion between the mixed-mode scattering parameters and the standard scattering parameters, and circuit analytical methods are discussed to realize the equal power division in phase from one differential input to two SE outputs. To verify the correctness of the proposed theory, a practical BTSE PD, which operates at 0.95 GHz, is designed and fabricated. The measured relative bandwidth is 26.3%, and the final circuit size is only $0.021~\lambda _{g}^{2}$ .

In this paper, a novel compact tunable coupled-line power divider using varactors is presented. It has a compact circuit due to the coupled line with short electrical length. The operating frequency can be flexibly controlled by the bias voltage because the capacitance of the varactors is regulated by the applied bias voltage. The theory of this power divider is analyzed and a microstrip example of this tunable power divider is designed, fabricated, and measured. The measured results indicate that the operating frequency of the proposed tunable power divider ranges from 0.8 to 1.15 GHz, agreeing well with the simulated result.