The technologies that result in wide tuning ranges and low phase noise in discrete oscillators can readily be adapted to integrated-circuit (IC) designs.
Technological advances often earn patents for their inventors. For large companies, such as IBM or Agilent Technologies, it is not unusual for multiple patents to be granted in a single year. But what makes the growing collection of US and overseas patents so unusual for Synergy Microwave (Paterson, NJ) is the relatively small size of the company in proportion to the number of patents pending and received in the past few years. With just over 100 employees, the company has amassed more than 20 patents since 2004, largely for technologies advancing the state of the art in microwave oscillator, mixer, and frequency synthesizers.
Communication systems rely on stable low-phase-noise signal source (oscillator/VCO), high-performance mixers and amplifiers to maintain phase-locked conditions and ensure transmitted data integrity. Phase noise and phase hits are a major concern because of its direct impact on system performance. Many third-and later-generation systems incorporate multiple narrowband oscillators/VCOs and mixers to cover their bandwidth requirements.
To overcome this problem, the design team of Synergy Microwave Corp. (Paterson, NJ) uses distributed coupling concepts in conjunction with noise-feedback and noise-cancellation approaches so that technology can be well-suited for discrete as well as integrated circuits. Stepping forward, Synergy made a technological breakthrough and developed a new class of microwave oscillators and mixers which can be used over multi-octave bands, but provide-good performance, are power efficient, are low in cost, and small in size. This work, partially sponsored and triggered by two government contracts from DARPA and the US Army, has produced several patent applications (see table) and publications.
Most recently, the company introduced a line of low-noise tunable phasehit-insensitive oscillators designed to provide the phase-noise performance of yttrium-iron-garnet (YIG) resonator oscillators but at a fraction of the size, power, and cost requirements (see Microwaves & RF, April 2006, p. 80). The firm's DCYR and DCYS series patent-pending distributedcoupled oscillators are available for various bandwidths from 250 to 6000 MHz. Typical phase noise is −132 dBc/Hz offset 100 kHz from 250-to-100-MHz carriers and −142 dBc/Hz offset 100 kHz from 150-to-600-MHz carriers.
As with many of the company's recently applied-for or received oscillator patents, the design methodology behind the DCYR oscillators pays close attention to coupling and matching of the active devices. The DCYR oscillators employ multi-coupled-slow-wave (MCSW) planar resonators with carefully chosen real and imaginary impedance for device-to-resonator matching that optimizes the oscillator's phase characteristic curve. Using a novel topology, the result is an oscillator with optimum dynamic coupling and quality factor (Q) resulting in low phase noise. Recent publications1-28 based on innovative technology yield cost-effective solutions without compromising performance of VCOs, amplifiers, mixers, tunable filters, and other discrete and integrated circuits (ICs), where performance levels are limited due to larger-bandwidth and low-noise criteria.
The firm's recent patent activities have included work on oscillators with low phase noise and low thermal drift (US Patent Application Publication No. US 2005/0046500 A1, "Tunable frequency, low phase noise and low thermal drift oscillator," filed on August 5, 2004 and with a patent publication date of March 3, 2005) as well as several applications/publications on wideband tuning oscillators (such as US Patent Application Publication No. US 2006/0033586 A1, "Low noise, hybrid tuned wideband voltage controlled oscillator," filed on August 16, 2004 and with a publication date of February 16, 2006). The first approach essentially uses dynamic biasing and feedback to send some of the noise generated by the oscillator's three-terminal (transistor) device back into the device in order to cancel some of the noise through out-of-phase mixing. The second approach involves the use of multiple coupled resonators to form a resonator network that is in turn coupled to the second terminal of a transistor. A tuning network is used with the coupled network to adjust the coupling between two or more of the resonators in the network.
The engineering team, led by Synergy chairman Ulrich L. Rohde (a recent nominee to the first Microwaves & RF "Legends" voting), includes designers well versed in innovative circuit techniques such as Ajay Kumar Poddar (a co-developer of the planar DCYR/DCYS oscillator topology, power-efficient high IIP3 mixer technology, noise cancellation, and mode coupling topology, controllable and definable thermal drift profile technology and many other exciting approach for noise minimization based on N-Push topology), Klaus Juergen Schoepf, Reimund Rebel, and P. Patel. They have succeeded in developing several approaches to widebandintegrated oscillators as well as oscillators that remain stable over wide temperature ranges (such as US Patent Application Publication No. US 2005/0280478 A1, "Low thermal drift, tunable frequency voltage controlled oscillator," filed on July 19, 2005 with publication date of December 22, 2005). In this latter architecture, for example, the active device is coupled to multiple resonators by means of an evanescentmode buffer in order to compensate for changes in oscillator capacitance due to temperature (see figure). A good summary of all the new developments was presented during the Frequency Control Symposium in Miami in May 2006 ("Novel Multi-Coupled Line Resonators Replace Traditional Ceramic Resonators in Oscillators/VCOs," IEEE International Frequency Control Symposium (IFCS), June 5-7, 2006.
The company has applied its technological advances to its own product lines, although these oscillators are fabricated with discrete devices. In developing these oscillator design approaches, Rohde noted that the patented technologies are ideally suited for IC processes, where current performance levels tend to show much higher phase noise than possible with discrete designs such as Synergy's oscillator products. While not desiring to create its own IC versions of its oscillators, Synergy has received requests for licensing its oscilator technologies from various companies, including qualified IC houses interested in improving the bandwidth, stability, microphonic-immunity, and phase noise of their on-chip tunable oscillators. Examples include integrated wireless transceiver ICs with on-board VCOs and synthesizers, as well as fractional-N, phase-locked-loop (PLL), and other synthesizer ICs with on-chip RF-MEMS tunable oscillators and tunable filters. The intellectual property (IP) gained in modecoupling and noise-cancellation techniques can be used with many applications in third-and later-generation wireless communications systems and test equipment.
For more information on the patented and patent-applied for oscillator technologies, visit the Synergy Microwave website at www.synergymwave.com. For information on licensing the technologies, contact Ulrich Rohde at the company. Synergy Microwave, 201 McLean Blvd., Paterson, NJ 07504; (973) 881-8800, FAX: (973) 881-8361, Internet: www.synergymwave.com.
- U.L. Rohde, "Ceramic Resonator Oscillators Challenges SAW," Microwaves & RF, pp. 100-105, September 2003.
- U.L. Rohde, K.J. Schoepf, and A.K. Poddar, "Low-Noise VCOs Conquer Wide Bands," Microwaves & RF, pp. 98-106, June 2004.
- U.L. Rohde and A.K. Poddar, "Noise Analysis of Systems of Coupled Oscillators," Integrated Nonlinear Microwave and Millimeter wave Circuits (INMMIC) workshop, Monte Porzo, Cantone, Italy, November 15-16, 2004.
- U.L. Rohde, "Designing an Ultra Low Phase Noise 4.5 GHz VCO Using Multiple Coupled Resonators and MOS Devices," IEEE Symposium, RFIC-2005, USA.
- U.L. Rohde and A.K. Poddar, "Ultra Low Noise Low Cost Multi Octave Band VCO," IEEE Sarnoff Symposium, Princeton, NJ, USA, April 18-19, 2005.
- U.L. Rohde, A.K. Poddar, Juergen Schoepf, Reimund Rebel, and Parimal Patel, "Low Noise Low Cost Wideband N-Push VCO," IEEE, IMS Symposium, MTT-S 2005, USA.
- U.L. Rohde, A.K. Poddar, and Juergen Schoepf, "A Unifying Theory and Characterization of Microwave Oscillators/VCOs," 18th IEEE CCECE05, May 2005, Canada.
- U.L. Rohde and A.K. Poddar, "Configurable Ultra Low Ultra Wideband Power Efficient VCOs," 11th European Wireless Conference, Cyprus, April 10-13, 2005.
- U.L. Rohde, A.K. Poddar, and Reimund Rebel, "Ultra Low Noise Low Cost Octave-Band Hybrid-Tuned VCO," 18th IEEE CCECE05, May 2005, Canada.
- U.L. Rohde and A.K. Poddar, "A Unified Method of Designing Low Noise Oscillator," International Microwave and Optoelectronics Conference (IMOC 2005), Brazil, July 25-28, 2005
- U.L. Rohde and A.K. Poddar, "Configurable Adaptive Ultra Low Noise Wideband VCOs," IEEE, ICU05, September 5-8, 2005, SFIT, Zurich, Switzerland.
- U.L. Rohde and A.K. Poddar, "Ultrawideband (UWB) RF Signal Source," IEEE, ISWCS2005, Italy, September 5-7, 2005.
- U.L. Rohde and A.K. Poddar, "Reconfigurable Wideband VCOs," IEEE, PIMRC2005, Germany, September 11-14, 2005.
- U.L. Rohde and A.K. Poddar, "MEMS Enabled VCO for Wireless Connectivity," GigaHertz2005, Sweden, November 8-9, 2005.
- U.L. Rohde and A.K. Poddar, "An Analytical Approach of Minimizing VCO Phase Noise," Asia-Pacific Microwave Conference, China, December 4-7, 2005.
- U.L. Rohde and A.K. Poddar, "Impact of Device Scaling on Oscillator/VCO Phase Noise in SiGe HBTs," International Semiconductor Device Research Symposium, ISDRS 2005, USA, December 7-9, 2005.
- U.L. Rohde and A.K. Poddar, "Distributed Coupled Resonator (DCR) Oscillator/VCO Limit Phase Noise and Phase Hits," IEEE Radio and Wireless System, San Diego, CA, USA, January 17-19, 2006.
- U.L. Rohde and A.K. Poddar, "Technological Scaling and Impact on UWB Configurable RF Signal Source," IEEE Sarnoff Symposium, Princeton, NJ, USA, March 27-28,2006.
- U.L. Rohde and A.K. Poddar, "UWB Configurable YRO," IEEE Sarnoff Symposium, Princeton, NJ, USA, March 27-28, 2006.
- U.L. Rohde, and A.K. Poddar, "Cost-Effective, Power-Efficient and Configurable YIG Replacement Signal Source," German Microwave Conference-GeMiC 2006, March 2006, Germany.
- U.L. Rohde, A.K. Poddar, and J. Schoepf, "Cost-Effective VCOs Replace Power-Hungry YIGs," Microwaves & RF, pp. 80-87, April 2006.
- U.L. Rohde, and A.K. Poddar, "Power-Efficient High Intercept Points Mixers For Wireless Communications," 19th IEEE CCECE05, May 7-10, 2006, Canada.
- U.L. Rohde and A.K. Poddar, "User-Defined and Configurable CSRO," 16th International Conference on Microwaves, Radar and Wireless Communications, MIKON, May 22-24, 2006.
- U.L. Rohde and A.K. Poddar, "Novel Multi-Coupled Line Resonators Replace Traditional Ceramic Resonators in Oscillators/VCOs," IEEE, International Frequency Control Symposium, IFCS, June 5-7, 2006, Florida, USA.
- U.L. Rohde and A.K. Poddar, "Impact of Device Scaling on Phase Noise in SiGe HBTs UWB VCOs," IEEE, IMS Symposium, MTT-S, June 11-16, 2006, San Francisco, CA, USA.
- U.L. Rohde and A.K. Poddar, "High Intercept Point. Broadband, Cost Effective and Power Efficient Passive Reflection FET DBM," EuMIC Symposium, September 10-15, 2006, UK .
- U.L. Rohde and A.K. Poddar, "MEMS Enabled Signal Source For Wireless Communication Systems," IEEE/ISWCS, September 6-8, 2006, Singapore.
- U.L. Rohde and A.K. Poddar, "Reconfigurable, Power Efficient, and High IP3 Passive FET Mixers For UWB Communication Systems," IEEE/ISWCS, September 6-8, 2006, Singapore.