Balanced Couplers Research Articles

Low crosstalk, low Pπ silicon optical switch based on highly balanced couplers and folded phase shifters

Low crosstalk, low Pπ silicon optical switch based on highly balanced couplers and folded phase shifters

Theoretical and experimental studies of multi-port RF power feeding in rod-type radio frequency quadrupole (RFQ) linac

An analytical and experimental study of multi-port RF power feeding in a four rod-type radio frequency quadrupole (RFQ) has been discussed. First, we have derived generalized relations for multi-coupler power feeding based on S-parameters for n balanced couplers. Using simulation and measurements on a prototype, the optimum position and orientation of two and four couplers in an 80 MHz extended vane rod type RFQ have been determined. A low power RF test has been carried out to show the phase and power balancing using S parameter analysis for two and four mock-up couplers for the RFQ. As a corroborative study, the vane tip voltage measured with a vector voltmeter showed that voltage corresponding to power fed through a single coupler (β = 1) agrees with the value when the same power is fed using two or four couplers.

Tunable Balanced Power Dividers: An Overview of Recently Developed Balanced Power Dividers and Couplers With Fixed and Tunable Functions

Signal crosstalk and common-mode noise are two issues for engineers when designing today's increasingly complicated microwave integrated circuits [1]. Compared with single-ended circuits, balanced circuits can provide high immunity to environmental noise and broadband common-mode rejection capability [2]. Over the past few years, various balanced passive circuits, such as filters [3], antennas [4], power dividers, and couplers [5]-[17], have been extensively studied. Power dividers and couplers are widely used in microwave integrated circuits, such as antenna feeding networks, balanced mixers, and amplifiers. Balanced couplers are used in double-balanced mixers [18] and balanced frequency doublers [19] to achieve higher efficiency and lower loss.

Dual‐band balanced coupler with wideband common‐mode suppression

A novel compact dual-band balanced coupler with differential-mode power division, broadband common-mode, and common-to-differential-mode conversion suppression is proposed. In these double-functionality balanced-coupler architectures, double-sided parallel-strip line 180° phase inverters are used to realize the broadband common-mode rejection. Moreover, the frequency is tunable by changing the characteristic impedance of the transmission line. For practical verification, a balanced couplers (εr = 2.65, h = 0.5 mm, tan(δD) = 0.003) operation at 0.9/1.8 GHz is constructed in microstrip technology and tested.

Balanced Rat-Race Couplers With Wideband Common-Mode Suppression

In this article, various types of six-port balanced rat-race couplers with wideband common-mode suppression characteristics are presented. In these couplers, the input and output ports can functionalize either as single-ended or differential terminals to realize different operational modes. The power-splitting ratio for these balanced couplers can be flexibly adjusted by means of the values of the characteristic-impedance parameters of their constituent transmission-line segments. Furthermore, the employment of double-sided-parallel-strip-line-(DSPSL)-based 180° phase inverters instead of half-wavelength transmission-line-based ones allows for the considerable enlargement of their operation bandwidth in more-compact circuits with lower in-band insertion-loss levels. For experimental-validation purposes, two microstrip prototypes at $f_{0}=0.9$ GHz with equal and unequal power division are fabricated and characterized. They exhibit common-mode rejection levels higher than 15 dB from 0 to 1.8 GHz (i.e., 0– $2f_{0}$ ) and differential-to-common- mode-conversion suppression levels above 15 dB within the spectral range 0–1.49 GHz (i.e., 0– $1.65f_{0}$ ).

Multi-Band Balanced Couplers With Broadband Common-Mode Suppression

Three novel single-/multi-band balanced couplers with wide-band common-mode suppression are proposed. In these double-functionality balanced-coupler architectures, double-sided parallel-strip line 180° phase inverters are used to realize the broadband common-mode rejection. Furthermore, by loading quarter-wavelength open/short-ended coupled lines at all ports of the single-band differential-mode coupler, dual/triple-band balanced operation with high isolation for the differential-mode power-division bands can be realized into it. For practical verification, three balanced couplers with single-, dual-, and triple-band operation at 1 GHz, 0.72/1.24 GHz, and 0.66/1/1.36 GHz, respectively, are constructed in microstrip technology and tested.

Broad-spectral-range synchronized flat-top arrayed-waveguide grating applied in a 225-channel cascaded spectrometer

We present a new synchronized design for flattening the passband of an arrayed-waveguide grating (AWG) over a broad wavelength range of 90 nm. A wavelength-insensitive 3-dB balanced coupler is designed to be used in duplicate in a Mach-Zehnder interferometer (MZI); the phase deviation created by one of the balanced couplers is cancelled by flipping the other coupler around. This MZI is arranged in tandem with the AWG such that the output signal of the MZI is the input signal of the AWG. We demonstrate a 5-channel, 18-nm-spacing AWG with a 0.5-dB bandwidth of 12 nm over a 90-nm spectral range. A low-loss cascaded AWG system is demonstrated by using the MZI-synchronized flat-top AWG as a primary filter.