Showing papers by "Ulrich L. Rohde published in 2006"

User-definable, low cost, low phase hit and spectrally pure tunable oscillator

Abstract: A tunable oscillator includes a first transistor, a second transistor connected in parallel with the first transistor, a noise feedback and bias network coupled to the first and second transistors, a planar coupled resonator network coupled to the transistors and a means for dynamically tuning the resonant frequency of the planar coupled network and the junction capacitance of the transistors.

Novel Multi-Coupled Line Resonators Replace Traditional Ceramic Resonators in Oscillators/VCOs

Abstract: Communication systems rely on stable signal source (Oscillator/VCO) to maintain phase-locked conditions and ensure transmitted data integrity. Many third and later generation systems incorporate multiple narrowband ceramic coaxial resonator oscillators (CROs) to cover their bandwidth requirement. Ceramic CROs are renowned for their ability to generate high spectral purity signal at RF/microwave frequencies. Unfortunately, CROs have several disadvantages, including a limiting temperature range, limited tuning range, not amenable for fabrication by current integrated circuit (IC) technology, and also sensitive to phase hits. These resonators are custom made for long lead-time and because of tension in crystal structure of the pressed and backed device, tend to cause phase hits in oscillators and synthesizers. This paper discusses the novel MCLR (multi-coupled line resonator) based oscillator/VCO, which is promising alternative of CROs, and supports better noise performance than commercial available high Q (quality factor) ceramic CROs at a fraction of cost.

Low Noise, Low Power Consumption, Configurable, and Adaptable Ultrawideband VCOs

Abstract: The different standards operating in the frequency range of up to 6 GHz, with even higher frequencies, arises the need and gives a key role to multi-standard RF transreceiver which combine several cellular and cordless phone standards as well as wireless LAN functionalities in one unit. Therefore, the "global roaming" features between wide varieties of networks operating at different frequencies call for the development of ultrawideband VCO (voltage controlled oscillator) that can cover wide frequency range. The VCO design approach demonstrated in this work can satisfy the need for the present demand for low cost, low noise, low power consumption, configurable, adaptable, and also easily amenable for integration in present integrated circuit (IC) technology in chip form. The measured phase noise is better than ?130 dBc/Hz at 100 kHz offset from the carrier over the tuning range (800-5600MHz), and to our knowledge, this is the lowest phase noise for this band by using SiGe HBT (Infineon BFP740) reported to date, and the topology is not limited to these frequencies, can be easily extended to other higher frequency band (L, S, C, X, and Ku band).

Impact of Device Scaling on Phase Noise in SiGe HBTs UWB VCOs

Abstract: The performance of the electronic system strongly depends on the speed of devices, and technological scaling has driven this momentum towards achieving faster speed and high level of integration. Device scaling has been the principal driving force behind the technological innovations, and breakthrough of the past century. This paper investigates the impact of device scaling on oscillator/VCO phase noise in SiGe HBTs, which has recently emerged as a strong contender for RF and mixed signal applications. The relative contribution of the broadband (thermal and shot noise) and low frequency (1/f noise) noise sources are examined with respect to the device scaling. An approach of minimizing the phase noise with respect to the scaling is discussed, and demonstrated for distributed coupled resonator (DCR) based ultra wideband (UWB) VCOs. The measured phase noise is typically ?115 dBc/Hz at 100 kHz offset over the tuning range (2-6 GHz), and to our knowledge, this is the best phase noise performance for this band using printed multi-coupled resonator with SiGe HBT (Infineon BFP 740) so far reported.

Technological scaling and minimization of 1/f noise in SiGe HBTs coupled mode N-Push oscillator/VCO

Abstract: This paper discusses the impact of technological scaling and minimization of flicker (1/f) noise on SiGe HBTs in coupled mode N-push oscillator/VCO configuration, which has recently emerged as a strong contender for RF and mixed- signal applications. 1/f noise in SiGe HBTs is sensitive with device scaling and significantly up- converted in coupled mode oscillators due to the presence of asymmetrical output from their subsequent N oscillator sub-circuits that forms N-push configuration. Improving the symmetry of the coupled mode N-Push topology develops a method of minimizing the 1/f noise up-conversion and phase noise in the scaled device. The experimental result shows 12 dB improvement in the noise performances for a typical symmetrical coupled mode VCO at 10 kHz offset from the carrier frequency 8000 MHz in comparison to the asymmetrical version of the coupled mode scaled device (SiGe HBTs).

Distributed coupled resonator (DCR) oscillators/VCOs limit phase noise and phase hits

Abstract: Communication systems rely on stable signal source (oscillator/VCO) to maintain phase-locked conditions and ensure transmitted data integrity. Many 3/sup rd/ and later generation systems incorporate multiple narrowband oscillators/VCOs to cover their bandwidth requirement. The coexistence of second and third generation wireless system requires multi-mode, multi-band and multi-standard mobile communication systems, therefore, requiring a wideband source that may replace several narrow band SAW/ceramic resonator VCO modules by a single low noise wideband distributed coupled resonator (DCR) VCO with minimal phase hits. The distributed coupled resonator (DCR) VCOs demonstrated in this work can satisfy the need for the present demand for low cost, low noise, low phase hits, wide tuning range, power efficient, compact size, and amenable for integration in chip form. The measured phase noise is better than -132 dBc/Hz at 100 kHz offset over the tuning range (1800-3250 MHz), and to our knowledge, this is the best phase noise performance for this band using printed coupled resonator with discrete components so far reported.

LC oscillator circuit with a compensation coil for parasitical collector capacitor

Abstract: An oscillator circuit configuration comprising in an LC-parallel oscillatory circuit and a transistor as an amplifying element. A compensating winding is associated with the parallel oscillatory circuit whereby the collector voltage of the transistor is fed to said winding in order to compensate the effect of the parasitic collector capacity. Preferably, the collector current from the transistor is maintained constant be an amplifier.

Multi-Mode Wideband Voltage Controlled Oscillators

Abstract: Communication systems rely on stable VCO (voltage controlled oscillator) to maintain phase-locked conditions and ensure transmitted data integrity. Many third and later generation systems require multi-mode or multi-band signal sources (VCOs) to cover their bandwidth requirement. This paper presents the design of a dual-mode oscillator that simultaneously generates two signals at different frequencies. The novel approach is based on multi-mode frequency generation technique without recurring the switched inductors and varactors networks, and also support improved phase noise performance for a dual-mode operation over the band. The measured phase noise for mode #1 (450-900 MHz) and mode #2 (900-1800 MHz) are typically -120 dBc/Hz, and -112 dBc/Hz at 10 kHz offset from the carrier frequency respectively; and to our knowledge, this is the best phase noise performance for this class of VCO by using planar CMR (coupled microstripline resonator) so far reported.

Power-Efficient High Intercept-Points Mixers for Wireless Communications

Abstract: A unified approach of designing cost-effective, power-efficient and high intercept point passive double balanced mixer (DBM) is reported. This work is based on switching devices as a mixing cell (dual FETs) where gate's capacitances are resonated by using hybrid resonance network for minimization of LO power level and nonlinearity of the mixing cell. The passive reflection FET mixers based on present approach can operate with low noise figure and high dynamic ranges without the need of excessively high LO drive level. This paper is based on patent pending approach that gives input intercept points (IIP3) in excess of 40 dBm and conversion loss less than 9.5 dB with the LO power typically 17 dBm for the frequency bands (RF: 650-1500 MHz, LO: 700-1700 MHz, IF: 50-200 MHz). The interport isolation is improved by minimizing signal leakage between ports through amplitude and phase cancellation techniques, and is better than 30 dB for broadband applications. To our knowledge, the mixer circuits reported in this work exhibit best performance (for this class of circuits and given size and cost) to date, and easily amenable for integration in MMIC form. The circuit topology is not limited to these frequencies, and can be easily extended for other frequency band to meet the requirement of present and later generation of communication systems

Cost-effective VCOs replace power-hungry YIGs

Abstract: These innovative voltage-controlled oscillators make the most of multi-coupled slow-wave planar resonators to achieve low phase-noise performance at a fraction of the size and power of YlGs.

RF-MEMS Enabled RF-Signal Source For Low-Power Consumption Ultrawideband Communication Systems

Abstract: RF-MEMS based components such as inductors, variable capacitors, transmission line, filter, switches, phase-shifter, and resonators are superior in performances in term of quality factor, noise, linearity, power consumption, size, and cost, which cannot be achieved by conventional approach, thereby, prime candidate for ubiquitous connectivity. This work discusses the recent trends in wireless connectivity and gives the brief overview of the RF-MEMS enabled front ends, especially, RF signal source (VCOs) that can be extended to microwave, and is also amenable for integrated circuit (IC) fabrication.

High Intercept Point, Broadband, Cost-Effective, and Power-Efficient Passive Reflection FET DBM

Abstract: A high intercept points, broadband, cost-effective and power-efficient passive reflection FET double balanced mixer (DBM) is reported. This paper is based on novel approach that gives intercept points (IP3) in excess of 42dB in and conversion loss less than 9.5 dB with the LO power typically 17dBm throughout the frequency bands (RF: 600-2500MHz, LO: 550-2300MHz, IF: 50-200MHz). The interport isolation is better than 30 dB for broadband applications, and the circuit topology is not limited to these frequencies, and can be easily extended for present and later generation of communication systems

Technological Scaling and Impact on UWB Configurable RF Signal Source

Abstract: The coexistence of second and third generation wireless system requires multi-mode, multi-band and multi-standard mobile communication systems, therefore, requiring a configurable RF signal source (VCO) that may replace several narrow band VCO modules by a single low noise ultrawideband (UWB) adaptable RF signal source. The performance of the wireless communication systems strongly depends on the speed of devices, and technological scaling has driven this momentum towards achieving faster speed and high level of integration. This paper investigates the impact of device scaling on phase noise of the UWB (2-8GHz) configurable coupled N-Push voltage controlled oscillator (VCO) in SiGe HBT, which has recently emerged as a strong contender for RF and mixed signal applications.

UWB Configurable YRO

Abstract: Ultrawideband (UWB) has drawn the interest among the research and wireless communication communities due to its configurability and adaptability, which enables it to coexist with many concurrent services. YIG (Yttrium-Iron- Garnet) based signal sources are renowned for their configurability, wideband tunability and ability to generate high spectral purity signal at microwave frequency. However, YIG based signal sources are costly, power hungry, and not suited for fabrication by current integrated circuit (IC) technology. Nor are they immune to electromagnetic interference (EMI), vibration effects, microphonics, phase hits, and frequency modulation. This paper discusses the technology of the YIG replacement oscillator (YRO) as a UWB configurable signal source, which is cost effective and easily amenable for integration in IC form.

Reconfigurable, Power Efficient, and High IP3 Passive FET Mixers For Wideband Communication Systems

Abstract: Wireless systems operate in high interference environments, therefore very much prone to distortion, where mixers are frequently the dominant circuit components in establishing the overall system's distortion performance. The emerging wireless standards have pushed researchers to look for cost-effective, power-efficient, and high IP 3 (third order intercept point) wideband mixer that can satisfy the present and future requirement of wireless service, which comes with the necessity of multi-band, multi-mode, and multi-standard trans-receivers systems. The passive FET mixer using hybrid-resonance switching and feedback mechanism demonstrated in this work offers low cost, low distortion, low-LO power, high input intercept points (IIP3), broadband operation, compact size, reconfigurable, and easily amenable for integration in integrated circuit (IC) form.

Phase Hits Insensitive CSRO

Abstract: Ceramic coaxial and SAW (surface acoustic wave) resonators are renowned for their ability to generate high spectral purity signal at microwave frequency. However, Ceramic and SAW based signal sources are costly and not suited for fabrication by current integrated circuit (IC) technology due to their 3-D (Three-Dimensional) structure. Nor are they immune to electromagnetic interference (EMI), vibration effects, microphonics, phase hits, and frequency modulation. This paper describes CSRO (Ceramic and SAW replacement oscillators), which is based on novel mode-coupled stubs-tuned planar resonators that offer user-definable, cost-effective, phase hits insensitive, integrable, compact, and low cost signal source for present and later generation wireless communication systems.

User-Defined and Configurable CSRO

Abstract: Ceramic/SAW (surface acoustic wave) resonators based oscillators are known for their ability to generate high spectral purity signal at microwave frequency but they are not immune to electromagnetic interference (EMI), vibration effects, microphonics, phase hits, and frequency modulation. Moreover, Ceramic/SAW resonators are costly and not suited for fabrication by current integrated circuit (IC) technology. This work is based on innovative and novel approach by using buried multi-mode-coupled planar resonators that offer user-definable, configurable, cost-effective, phase hits insensitive Ceramic/SAW replacement oscillators (CSRO). The typical measured phase noise of CSRO for frequency 2488 MHz is better than -164 dBc/Hz @ 1 MHz offset from the carrier, and is better than the commercial available Ceramic/SAW resonators based oscillators.

MEMS Enabled Signal Source For Wireless Communication Systems

Abstract: The application of RF MEMS (radio frequency micro electro Mechanical system) is on the verge of revolutionized wireless communications. RF MEMS offers a class of new devices and components that exhibit superior RF performance relative to conventional semiconductor devices, and also electronically reconfigurable. The current diversities of available services comes up with the necessity of multi-standards trans receiver operating in several frequency bands, therefore, present paper describes the overview of the RF MEMS based components and approach for configurable signal source (VCO) and antennas for third and later generation of wireless communication systems.

A Unified Method of Designing Ultra-Wideband Power-Efficient, and High IIP3, Reconfigurable Passive FET Mixers

Abstract: The current diversity of available wireless services comes up with the necessity of multi-mode, multi-band, and multi-standard trans-receivers operating in several frequency bands, therefore, requiring a wideband mixer circuit that may replace several narrow band mixer modules by a single low distortion ultra wideband mixer. The passive FET mixers based on present approach (patent pending) can operate with low noise figure and high dynamic ranges without the need of excessively high LO drive level, and gives input intercept points (IIP3) in excess of 42 dBm and conversion loss less than 9.5 dB with the LO power typically 16 dBm for the frequency bands (RF: 800-3100MHz, LO: 850-3300 MHz, IF: 50-200 MHz). To our knowledge, the mixer circuits reported in this work exhibit best performance (for this class of circuits, given size, power, and cost) to date, and the circuit topology is reconfigurable for other operating frequency band to meet the requirement of present and later generation of communication systems