Stephen Horst

Modified Wilkinson Power Dividers for Millimeter-Wave Integrated Circuits

A modification of the Wilkinson power divider is presented that eases planar implementation while maintaining performance. By adding transmission lines between the resistor and the quarter-wave transformers of the traditional design, a range of valid solutions exists that meet the conditions of being reciprocal, isolated between the output ports, and matched at all ports. The proposed design is particularly useful at millimeter-wave frequencies where reduced physical dimensions make a circuit configuration suitable for low-cost package-level implementation difficult using traditional methods. Two frequency bands are demonstrated. At V-band, the circuit gives 0.3-dB excess insertion loss, 19-dB isolation, and 50% bandwidth. At the W-band, the circuit gives 0.75-dB excess insertion loss, 24-dB isolation, and 39% bandwidth.

A Ka-Band Electronically Tunable Ferroelectric Filter

This letter presents a three-pole tunable Ka-band coplanar filter that includes six high-Q BST ferroelectric capacitors. It tunes from 29 GHz up to 34 GHz (17%) with low bias voltages ranging from 0 V to 30 V. The filter has fractional bandwidths of 9.5-12.2%. It has a good insertion loss for this category of Ka-band ferroelectric filters, which is between 6.9 dB (0 V) and 2.5 dB (30 V). Two tone measurements showed that the filter has a minimum OIP3 of 15 dBm between 0 V and 30 V. The highest OIP3 value is 26 dBm achieved at a dc bias of 30 V.

A Theory of Single-Event Transient Response in Cross-Coupled Negative Resistance Oscillators

A theory of the circuit-based response to SET phenomena in resonant tank oscillators is presented. Transients are shown to be caused by a change in the voltage state of the circuits characteristic differential equation. The SET amplitude and phase response is derived for arbitrary strike waveforms and shown to be time-variant based on the strike time relative to the period of oscillation. Measurements in the time-domain are used to support the theory, while the frequency-domain is used to gauge potential impact on system performance. A design-oriented analysis of the relevant trade-offs is also presented.

Slotline Stepped Circular Rings for Low-Loss Microstrip-to-Slotline Transitions

We propose a low-loss slotline (SL) stepped circular ring termination for use in a microstrip-to-slotline (MS-to-SL) transition. Not only does this termination achieve broadband characteristics, but it also reduces SL radiation. The experimental results show that, using the proposed technique, the radiation loss around the pass-band frequency is lower than that of the conventional transitions using radial or circular pad terminations

Modeling and characterization of thin film broadband resistors on LCP for RF applications

Resistors have several applications in high frequency circuits including uses in attenuators, terminations, and power dividers among others. To date, there has been very little attempt to characterize embedded resistor performance on organics above 18 GHz. In this paper, RF measurements of embedded thin film resistors up to 40 GHz are presented on a liquid crystal polymer (LCP) substrate using a commercially available laminated foil to form the thin film NiCrAlSi resistors. Measurements have been demonstrated to be accurate to 5% of their simulated values across the frequency band

Monolithic Low Cost Ka-Band Wilkinson Power Dividers on Flexible Organic Substrates

A millimeter wave Wilkinson power divider is presented on a thin and durable organic substrate, along with an analysis of bend topologies to reduce coupling between the output paths. The divider provides excellent performance across the entire Ka-band from 27 to 40 GHz. Insertion loss is approximately 0.3 dB and isolation between the output ports is around 30 dB at the design frequency.

Frequency- and amplitude-tunable X-to-Ku band SiGe ring oscillators for multiband BIST applications

An 8–17 GHz SiGe ring oscillator covering the X- and Ku-bands for built-in-self-test of multiband system-on-chip solutions is demonstrated. The oscillator features highly linear frequency control over the bandwidth, with 72% tuning range in a small form factor of 0.652 mm2. To the authors knowledge, this is the widest tuning range/smallest form factor combination achieved by a ring oscillator that spans both X and Ku bands. A second ring oscillator with band selectivity and output power control is also presented, covering the 9–11 GHz and 17–21 GHz bands. This second oscillator features an ultra-small form factor of only 0.036 mm2. Both oscillator designs are based on a 3.3 V supply and were implemented in a commercially-available 180 nm SiGe BiCMOS platform.

A Study of Total Dose Mitigation Approaches for Charge Pumps in Phase-Locked Loop Applications

An analysis of charge pump design for improved radiation tolerance of phase locked loops is presented. Two radiation-hardened-by-design approaches are considered to mitigate the total ionizing dose damage of the circuit, and a thick-film SOI SiGe process technology has been used to reduce charge collection of single event strikes. The results show that a modified design approach to implement the charge pump using SiGe HBTs can provide advantages in radiation tolerance to improve tri-state leakage performance, particularly for missions expecting large accumulated doses.

An investigation of electro-thermal instabilities in 150 GHz SiGe HBTs fabricated on SOI

We investigate, for the first time, the electro-thermal stability of 150 GHz SiGe HBTs that were optimized for bulk-Si and then fabricated on SOI substrates to enable a direct comparison. AC, DC and pulsed measurements are used to characterize the devices and study the onset of electro-thermal instabilities. Implications of electro-thermal feedback induced instabilities resulting from self-heating are discussed, along with consequent electrical biasing constraints imposed on the device. Figures-of-merit are proposed as effective tools for comparing devices with strong self-heating effects. TCAD is used to predict the implications for performance scaling and BiCMOS technology development for SiGe on SOI platforms.

An investigation of low-frequency noise in complementary SiGe HBTs on SOI

Low-frequency noise in complementary SiGe HBTs on SOI is investigated. Sib is extracted using a custom measurement setup, and the corresponding K factors are compared across multiple SiGe technology platforms for better understanding of SiGe evolutionary trends. We find that low-frequency noise has generally decreased with scaling for both npn and pnp SiGe HBTs, despite the low thermal cycles that aggressive scaling techniques utilized. In general, pnp SiGe HBTs have higher noise than npns, and this is true for Si BJTs as well as SiGe HBTs. The SiGe HBTs on SOI from an early C-SiGe platform presented here fit these trends, demonstrating their maturity and competitiveness. Low input-impedance noise measurement were also measured and analyzed in these SiGe HBTs, using a common-collector and a common-base configuration. We find that noise term Sic can be significant at high injection levels.