Projections Onto Convex Sets (POCS) Based Optimization by Lifting

Two new optimization techniques based on projections onto convex space (POCS) framework for solving convex and some non-convex optimization problems are presented. The dimension of the minimization problem is lifted by one and sets corresponding to the cost function are defined. If the cost function is a convex function in R^N the corresponding set is a convex set in R^(N+1). The iterative optimization approach starts with an arbitrary initial estimate in R^(N+1) and an orthogonal projection is performed onto one of the sets in a sequential manner at each step of the optimization problem. The method provides globally optimal solutions in total-variation, filtered variation, l1, and entropic cost functions. It is also experimentally observed that cost functions based on lp, p<1 can be handled by using the supporting hyperplane concept

Multi-Gigabit Wireless Link Development

CSIRO ICT Centre is developing millimetre wave point-to-point links suitable for multi-gigabit wireless connectivity. Suitable spectrum for this purpose is allocated at the 60 GHz band and above. This paper reports a new point-to-point link that will be installed at Marsfield site to demonstrate multi-gigabit operation and performance of its key components. The link will operate at the 81-86 GHz band incorporating CSIRO designed millimetre wave MMICs and multi-gigabit modems

A wideband transformer-coupled frequency quadrupler using an asymmetrical balun in 0.25μm SiGe for backhaul communication

© 2015 IEEE. A transformer-coupled frequency quadrupler with 50% bandwidth is designed in a 0.25μm SiGe process. The quadrupler covers an output frequency range from 36GHz to 60 GHz with a total power consumption of 38.5mW for a supply voltage of 2.5V. To fulfil the requirement of harmonic suppression, a novel on-chip asymmetrical Marchand balun structure is adopted to compensate the phase and amplitude errors across a wide bandwidth, so that the 3rd- and 5th harmonic suppressions of more than 30-dB can be achieved. The transformer-coupled approach along with a common-base configuration is adopted to enlarge the bandwidth of the multiplier

Very low frequency s-parameter measurements for transistor modeling

Correct measurement of low frequency noise in a transistor requires prior knowledge of its s-parameters but the measurement of s-parameters at very low frequencies are difficult due to long time constants of the measurement setup and instabilities in the transistors. We report a method to stabilize and measure the s-parameters of GaAs heterojunction bipolar transistors (HBT) at frequencies as low as 10 Hz to 1 MHz, and discuss an industry standard transistor model at these frequencies.4 page(s

An Edge-Coupled Marchand Balun with Partial Ground for Excellent Balance in 0.13 μm SiGe Technology

An edge-coupled meandered three-coupled-line Marchand balun with a partial ground plane implemented in 0.13 μ {m} SiGe Bi-CMOS technology is presented in this brief. The balance performance of the designed balun is significantly improved by creating a 'no ground plane' beneath the coupled-line structure, which is demonstrated by simulating two baluns: one with a partial ground and the other with a solid ground underneath. The measured amplitude and phase imbalances are less than 0.4 dB and 2.5°, across the 3-dB bandwidth from 21.5 to 95 GHz, surpassing previously reported results of edge-coupled Marchand baluns. The balun occupies 230 μ \text{m}\,\,×370\,\,μ {m}

A K-Band Frequency Doubler with 35-dB Fundamental Rejection Based on Novel Transformer Balun in 0.13-μm SiGe Technology

© 2016 IEEE. A compact balanced frequency doubler with more than 35 dB odd-harmonic rejection and fractional bandwidth of 73% is presented in this letter. Wide bandwidth and high odd-harmonic suppression is achieved by adopting a new technique for the transformer balun design, resulting in a very low magnitude imbalance of 0.13 dB and a phase imbalance of 0.4° over 7-15 GHz. The balun performance is improved by offsetting the radius of the primary and secondary coils, which reduces the parasitic coupling capacitance. The input and output frequency ranges for the doubler are 7-15 GHz and 14-30 GHz respectively. The circuit was fabricated in 0.13-μm SiGe technology. The chip size is 0.6 mm ×, 0.4 mm

An ultra-compact integrated millimeter-wave coupled-line resonator and a bandpass filter in silicon-germanium technology

© 2016 IEEE. An ultra-compact integrated resonator and bandpass filters (BPF), in silicon-based technology, are presented for millimetre-wave applications. The resonator consists of two broadside-coupled lines in opposite orientations. Using this resonator, a first-order and a second-order BPFs were also designed. To prove the concept, three prototypes of each of the resonator and the first-order BPF were fabricated using a standard 0.13-μm SiGe process. The measured results show that the resonator has an attenuation of 13.7 dB at the resonance frequency of 57 GHz, while the BPF has a centre frequency of 31 GHz and an insertion loss of only 2.4 dB. Excluding the pads, the chip size of both the resonator and the BPF is extremely compact, only 0.024 mm2 that is equivalent to 0.001 λg2. The unloaded Q factor of the filter is higher than other state-of-the-art designs