Ultra-­Broadband Communications using Transformer-­Based Poly-­Phase Network

Technology #6975

Background: Different communication systems such as RF (Radio Frequency), mm-­Wave (Millimeter) and Mixed Signal circuits use quadrature signal (I/Q) signals in their operation. Generating these quadrature signals efficiently is a key requirement in the design of these systems. Many of the current designs struggle with passive loss, amplitude/phase balance, bandwidth, and robustness of the quadrature
signals generated, which in turn limits system capability and overall performance. These performance issues are related to the use of RC-­CR (R-­Resistive, C-­Capacitive) pairs and poly-­phase extensions for the generation of quadrature signals in current designs. This invention seeks to overcome these and other performance related issues by developing a novel transformer-­based poly-­phase network topology which
substantially extends the operational bandwidth while minimizing loss and providing for good amplitude matching.

Technology: In this invention, a differential folded transformer quadrature coupler is used for generating high quality, fully differential signals that have low-­loss, ultra-­broad bandwidth and can be fabricated in a compact package. The design has been implemented in a standard 65nm bulk CMOS process and high quality quadrature signals over a decade bandwidth generated. The proof-­of-­concept design of a 3 stage transformer poly-­phase network showed strong performance over a 2-­20 GHz operating range and low values for output phase error, magnitude mismatch and image rejection ratios. In addition to superior performance, this design can be implemented in a significantly reduced chip area allowing for easier on-­chip, fully integrated system implementation. A high degree of design robustness is also achieved in this design by the ability of the poly-­phase network to suppress any common magnitude/phase offset.

Potential Commercial Applications:
Many communication and sensor systems can benefit from this technology. The most common area would be in wireless communication systems used in smartphones and other products. Other areas of use include radar systems of the phase array or mode-­former types and RF/mm-­wave/sub-­mm-­wave systems for high-­performance radar, phased-­array, imaging, high-­speed communication, and spectroscopy.

Benefits/Advantages:
• Low loss, compact design, high quality quadrature
signal generation and extremely wide operational
bandwidth (10:1 bandwidth)
• Generates high-­quality fully differential quadrature
signals while being compatible with output-­output
loading effect
• Can be readily extended to high-­order configurations for
broadband operation
• Performance and capability is unmatched by any other
currently used design