We present a robust, chip-scale packaged FBAR oscillator that is compatible with high volume manufacturing. The oscillator's extremely small size (area <; 1 mm2, thickness = 0.23 mm) combined with an SMT-compatible pad design enables integration of the timing function in-package with a companion ASIC. We have measured tens of thousands of oscillators operating at a native frequency of 2.6 GHz and observe mean jitter less than 10 fsec (12 kHz to 20 MHz offset), with many devices better than 8 fsec. The mean phase noise is -158 dBc/Hz at 800 kHz offset and -118 dBc/Hz at 10 kHz offset. The device draws 18 mA at 3.3V, and the phase noise at all frequency offsets remains within 1 dB over the temperature range from -40 to 125°C. Far from carrier noise is set by the power delivered to the resonator. Due to the ability of the resonator to remain linear at high power, far-from-carrier phase noise is as low as -165 dBc/Hz. The sensitivity to acceleration of these oscillators is better than 0.1 ppb/g. Hermeticity tests carried out on the chip-scale package indicate that the oscillators behave with the same level of integrity as our standard FBAR filters. Preliminary studies on aging have determined an upper bound on frequency drift. Including contributions from supply and load sensitivity, temperature, and aging, total frequency drift is less than +/-200 ppm.

We present a FBAR oscillator that operates at 628MHz, achieves low jitter <;50fs and good frequency stability all while fitting in a small package of 1.1 × 0.9 × 0.25 mm3. The chip-scale oscillator employs a feedback circuitry in the encapsulating lid of a FBAR resonator and makes use of a differential Colpitts oscillator design fabricated in 0.6μm CMOS technology. To achieve the frequency precision required for a reference oscillator, we demonstrate the ability to tune the oscillator over 700ppm using a switched capacitor scheme to compensate for manufacturing tolerances. For achieving frequency stability over temperature and packaging stress, the FBAR resonators used in these oscillators employ silicon dioxide layer temperature compensation and a stress relieved structure respectively. The measured integrated jitter (12kHz to 20MHz) for the oscillators with a supply voltage of 3.3V across a wafer is 33fs with a far from carrier phase noise of -170dBc/Hz .The median current draw from the supply is 16.5mA and the output power measured at a 50ohm load using a balun is 0dBm.These oscillators are suitable for co-integration as reference clocks in high speed communication ICs where size and performance are paramount.

We present a fourth-design generation Free Running Oscillator and Voltage Controlled Oscillator using integrated bipolar circuitry in the lid wafer with a temperature-compensated FBAR resonator in the base wafer. The goal is to produce a high frequency, low-noise oscillator. Because there are ~15,000 oscillators per wafer, we can develop very sensitive testing procedures to study the oscillator behavior. For example, we have determined our frequency measurement accuracy and precision to be ~ 0.2 parts-per-million (1 σ), and our phase sensitivity floor to be less than -180 dBc/Hz. Measurements on package hermeticity, suggest that the oscillators behave with the same level of integrity as our standard FBAR filters.

We demonstrate a 2.6 GHz chip-scale oscillator that measured phase noise better than -150 dBc/Hz at 1 MHz offset and integrated jitter of just 25 fs. The part was designed with differential out and drives a 100 Ohm differential load with a mean voltage swing of 100 to 200 mV. The phase noise at 10 kHz offset is -110 dBc/Hz. The device runs at 3.3V and Idd is just over 9mA (including buffer). Another variant is designed to have an on-chip varactor allowing tuning of 615 ppm/V over the targeted 0.5 to 1.8 V tuning range. Here, the integrated jitter degrades by 2X at 0 V Vtune and we measured 85 fs jitter at 1.5 V Vtune. Still, the integrated jitter was well below 100 fs. The all-silicon packaged part is designed to directly solder down onto a PCB. There are no bond wires used in the assembly of this device. The height of the soldered part is under 0.25 mm, and the area of the die is less than 1 mm 2 . The oscillator uses a Zero Drift Resonator (ZDR) FBAR and we see about +/- 100 ppm temperature drift from -40C to +110°C. The design uses a cross-coupled architecture with the ZDR and is ac-coupled to a buffer amplifier.

We present the first IC oscillator using acoustically coupled FBAR's with a 3.75% tuning range. The tuning range is higher than previous low-power FBAR oscillators and wide enough to cover the individual ISM bands. The high Q of the resonator enables to achieve a phase noise of -144.35dBc/Hz at 1MHz offset with a carrier frequency of 1.55GHz and a power consumption of 11.7mW. The miniaturized coupled FBAR die is (500×540)μm 2 . The active area of the CMOS is (600x550)μm 2 .

Recently, a new standard has been proposed to augment the performance of future Global Positioning System (GPS) receivers, and is generally referred to as the Global Navigation Satellite System (GNSS) band. By also requiring differential signals from the output of the filter to the cell phone receiver, further performance improvements can be obtained. To accommodate the new GNSS specifications and to provide single-ended to differential (SE-DE) mode conversion, new filter designs are required. In this work, we describe a two-stage, SE-DE filter design for GNSS that is based on coupled resonator filter (CRF) technology. The design provides insertion loss better than -2.5 dB over a frequency range greater than 56 MHz. Out-of-band rejection is greater than 40 dB from DC to 6 GHz, and better than 60 dB below 2 GHz. As a stand-alone filter, excellent phase and amplitude balance are achieved without the need for external inductors. In a frontend module consisting of the filter and an Avago LNA, we have measured >;13 dB gain over the GNSS band. The module also shows excellent rejection and true differential output equivalent to surface acoustic wave filter solutions.

First results on a novel voltage controlled oscillator (VCO) in the lower gigahertz range, featuring excellent phase noise and high power efficiency are presented. The heart of the VCO is a recently reported novel miniature two-pole decoupled stacked bulk acoustic resonator (DSBAR) filter. With its single 180° phase transition over the 1 dB bandwidth, linear phase, and maximum 1 dB insertion loss, it provides stable single-mode operation over 45 MHz (≈3%) of tuning bandwidth and has negligible heat dissipation when operated at incident power levels of 100 mW or greater. The 1.55-GHz laboratory VCO prototypes operate at 5 V supply voltage, 50 mA supply current, 15 dBm of output power, and >13% efficiency, demonstrating -84 and < -180 dBc/Hz phase noise suppression at 1 kHz carrier offset and in the thermal noise region, respectively. VCOs with cascaded DSBAR filters for further phase noise reduction are also demonstrated.

Two filter applications, GPS and Wi-Fi, using bulk wave coupled resonator filters (BWCRF) are discussed. The device consists of two FBAR resonators stacked one on top of the other and separated by a thin de-coupling layer. We refer to this device as a De-Coupled Stacked Bulk Acoustic Resonator or DSBAR. These devices can be used as stand-alone filters or together with similar devices to create very small filters capable of single-ended to single-ended or single-ended to differential conversion. Also, due to the unique arrangement of the two FBAR one on top of the other, an impedance transformer can be made. Lastly, these devices have a very short “ring-down” time compared to “classic” FBAR filters, important for OFDM applications.

Coupled resonator filters designed using a single-layer coupler require coupling materials with an acoustic impedance less than 5.0 MRayl. Carbon-doped oxide, with an acoustic impedance of 4.8 MRayl and an acoustic attenuation of 200 to 600 dB/cm at 1 GHz, can be used as a single-layer coupler to produce a competitive 2-stage coupled resonator filter for cellular handset applications in the gigahertz frequency range. The electrical response of our filter is superior to that of coupled resonator filters using a traditional acoustic mirror as the coupling element. We present an ultra-miniature 0.58 mm x 0.38 mm coupled resonator filter operating at a frequency of 2.15 GHz.

We describe a newly developed de-coupling material SiOCH for coupled resonator filter applications. The SiOCH films belong to a general class of low-k dielectrics often referred to as carbon-doped oxides (CDO). In this work, CDO replaces SiLK, significantly improving the performance of the resulting filters. In contrast to the spin-on and curing process used to deposit SiLK, the CDO films are deposited using plasma enhanced chemical vapor deposition. The resulting films possess a low acoustic impedance that can be varied over a range greater than 2:1 through a choice of deposition conditions. The new filters possess several key advantages over the SiLK-based devices reported previously, including decreased filter insertion loss, a passband free of spurious notches, and a dramatically lower temperature coefficient of frequency.

We present a filter for the 2.4 GHz ISM band that has both filtering and balun functionality to deliver a single ended to differential (SE2DE) filter response and 4:1 impedance transformation. We integrate the balun and filter response into a single chip using two FBAR resonators stacked one on top of the other and separated by a thin, low acoustic impedance material. True SE2DE behavior is achieved by dividing the bottom FBAR into two 100 Ohm resonators and hooking them in parallel to present a 50 Ohm impedance to the endpoint. The two 100 Ohm resonators forming the top of the stack are connected in series to present a differential output impedance of 200 Ohms. Since the entire device is not much larger than a single 50 Ohm resonator, the total die size is extremely small (much smaller than a typical FBAR half ladder filter utilizing 4 to 8 resonators).

A novel high isolation piezoelectric transformer operating in the UHF band is presented. The acoustically coupled transformer (ACT) is composed of thin film PZT transducers on both sides of an insulating substrate. The input transducer launches an acoustic wave through the insulating substrate to the output transducer in a pitch/catch mode to realize a 1:1 turns ratio. Appropriate series connection of multiple input transducers and parallel connection of the corresponding output transducers results in a transformer with an N:1 turns ratio. The ACT is fabricated using standard thin film and wafer scale fabrication techniques on a 150 mm diameter alumina wafer. The PZT transducers are deposited on Pt electrodes on both sides of the substrate by a sol-gel method. A backside photo-aligner is used to assure alignment of front and back side devices. Thousands of transformers can be made at once, thus eliminating costly one-off manufacturing. A novel differential electrode structure is used to apply the electric field to the PZT transducers without the need to etch the PZT film to reach the bottom electrode. Scattering (S) parameters of the ACT devices were obtained experimentally with a novel double-sided probe station that used air co-planar microprobes and a differential network analyzer. ACT transformers of 1:1 voltage ratio, with high DC isolation, and operating in the 20 to 200 MHz range are realized. The transformers exhibit a series of low insertion loss resonant peaks, spaced ~12 MHz apart, with |S 21 | as low as -1.2 dB when conjugate matched at the input and output ports. A temperature coefficient of frequency of -49 ppm/degC is measured. Power densities in excess of 400 Watts/cm 3 are achieved. Dispersion diagrams for the allowed vibration modes are presented.