Accurate Isolation Networks in Quadrature Couplers and Power Dividers

Abstract

When quadrature couplers and power dividers are implemented in integrated circuits, accurate isolation networks can not be realized due to the nonideal resistors and the process variations. We present an isolation network design technique which cancels the resistor parasitic effects and also increases the tolerance to variations in the resistance values. A Lange coupler and a power divider are designed at Ka-band using the proposed accurate and process-tolerant isolation networks. The improvement is analytically shown and empirically verified with our in-house GaN-based microstrip MMIC process. For the coupler, the measured return losses and isolation are better than 20 dB from DC to 40 GHz. The power divider achieves 20 dB return losses and isolation in a fractional bandwidth of 50%. Both devices maintain 20 dB performance even when the variation in sheet resistance is as high as 30%.

Near Field Sensing Applications with Tunable Beam Millimeter Wave Antenna Sensors in an All-in-One Chip Design

“…The common coupler types are Parallel-line coupler, Branch-line coupler [55][56][57][58][59], Ratrace coupler [56,57,[60][61][62], Lange coupler, Directional coupler [63][64][65], Lumped-Element coupler [66], and Hybrid coupler [67,68]. The design can be achieved by various structures such as Coplanar waveguide (CPW), Substrate-integrated waveguide (SIW), Microstrip line, etc.…”