This work presents two calibration-free 7-nm phase-locked loop (PLL) prototypes with high-frequency reference (high-ref): a 240-MHz-driven conventional xor-phase-detector-based PLL and a 2285-MHz-driven harmonic-mixing (HM) PLL, achieving FoMs of -258 and -261 dB, respectively. A frequency-domain analysis of the phase detector’s (PD’s) linearity and gain validates the xor PD as an optimal choice for high-ref PLL architectures. In addition, a first-order pulse-position modulation (PPM) noise model, which arises in high-ref PLLs, is incorporated into Perrott’s existing delta-sigma modulator (DSM) noise model, providing guidance on the choice of reference frequency in high-ref PLL architectures.

There are several filter technologies based on acoustic properties. Low-cost, low- performance filters tend to be dominated by LT SAWs and high cost, high performance filters are dominated by FBAR and IHP (POI surface wave devices). In between are Temperature Compensated SAWs (TCSAWs). Adding to this retinue of technologies are bonded LT to SAWs (the LT is 5 to 20 um thick) where, in our case, the LT/SI interface is apodized to eliminate parasitic bulk modes. This technology coupled with an aggressive polymer-based wafer-scale package allows for integration of the band1 and band3 duplexers into a single die quadplexer that is~2mm 2 in area and can easily fit into a 2.0 X 1.6 mm 2 package.

Today's phones have as many as 60 front-end radios covering multiple frequency bands. For each frequency band, acoustic filters offer high-Q, good power handling, and linearity in a very small package. These properties are crucial when addressing the "explosion" in the number of radios and the filters needed by today's Smart Phones. Moving forward, filter integration will become essential for cost and size. A novel lithium tantalate (LT) bonded to silicon hybrid substrate silicon SAW (SiSAW) was developed that provides temperature compensation, good power handling properties, while mostly eliminating spurious modes created between the LT/Si interface. One of several advantages of this technique is that one can integrate as many filters as needed onto one die. This provides for cost savings as well as area savings while reproducing the inherent performance of high-quality temperature compensated (TC)-surface acoustic waves (TC-SAWs).

A 1mW −261dB FOM PLL with 91fs jitter is presented that combines a low-noise, high-frequency FBAR reference with the unity-gain harmonic-mixing (HM) PLL to minimize reference noise gain and avoid entirely the amplification of sigma-delta modulator quantization noise and fractional spurs, which, in turn, allows for a substantially larger loop bandwidth to suppress the VCO noise and speed settling.

Quartz crystals have dominated the timing market for the last 70 years. FBAR technology is poised to replace quartz for many high frequency applications. Integration of the ultra-small form factor of the microcap'd FBAR into the SoC BGA packages currently in the market will make these applications earn the moniker, "Crystal-less". To replace crystals for non-GPS applications, the FBAR must demonstrate superb aging properties, repeatable and well-behaved temperature stability, immunity to mechanical stress, high frequency with +/- 500 ppm accuracy and small size. We will present data showing that we have met all five properties described above. Furthermore, we have integrated 3 resonators into an all-silicon 0.5 × 0.5 × 0.2 mm 3 package targeting the 3 BLE advertising frequencies: 2402MHz, 2426 MHz and 2480 MHz.

This work presents a differential FBAR circulator that uses the bending mode to mechanically modulate the FBAR mode without any varactors or switches. The differential FBAR circulator achieves a 61.5 dB isolation (IX) with an insertion loss (IL) of 1.8 dB at 2.68 GHz, demonstrating the first MEMS-only circulator. The isolation bandwidth at -25 dB is 4.7 MHz and power handling of the circulator is limited by the FBARs to +34 dBm.

The oscillator architecture is proposed to reduce the close-in phase noise as well as power consumption. The proposed Colpitts oscillator removes the current source which is the main source of the 1/f noise conversion. The removal of the current source is compensated by using the transformer and cross-coupled capacitors. The 2-GHz film bulk acoustic resonator (FBAR) is used for the high Q frequency selective elements in the oscillator design. According to measurement results, this FBAR-based oscillator shows >= 10 dB reduction in close-in phase noise. Specifically, 12-dB lower phase noise is achieved at 100 Hz offset frequency. Measured power consumption is 350 uW, which is almost half of the conventional Colpitts oscillator using same FBAR device.

We present an oven-controlled FBAR oscillator that achieves a frequency stability of +/-1.55ppm from -5°C to 85°C. The highly integrated system includes a 0.64mm2 FBAR chip with integrated heater and sensor resistors and a 3 mm2 CMOS chip with the control electronics. The oscillator achieves an Allen deviation of 4ppb enabled by a temperature-to-digital converter (TDC) with a 150uK resolution. It corresponds to a 1.68JK2 FOM. The heater consumes a power of 14mW at -5°C and the oscillator consumes only 0.25mW. The ovenized oscillator meets the stringent frequency stability requirements (2 ppm) of GPS applications.

Using first principles and the constitutive equations of a piezoelectric crystal, we solve the 2-D problem inside a three-layer film bulk acoustic resonator (FBAR) in order to study the dispersion and parasitic lateral modes’ characteristic of the structure. In our main lateral mode approximation, described here in detail, we construct the acoustic wave by combining the ideal “piston” mode and the main dispersion branch lateral mode. By limiting our analysis to the practical range of frequencies near the series resonance of the stack, where the lateral component $k_{x}$ of the ${k}$ vector is small, we find analytical expressions for the FBAR acoustic wave and for the dispersion of the three-layer stack. When lateral boundary conditions are added to the acoustic problem of a laterally finite resonator, we employ our theory to estimate the amplitude and the propagation of the lateral modes and then compare the theoretical predictions with the measurements of fabricated FBARs and finite-element simulation results. We are able to distinguish between a “clamped” and a “quasi-free” lateral interface by comparing the amplitude strength of the lateral modes produced, and we discuss how optimum lateral boundaries can be engineered with perimeter frames for realistic resonators.

This letter presents the experimental demonstration of a film bulk acoustic resonator (FBAR) circulator at 2.5 GHz. The circulator is based on spatiotemporal modulation of the series resonant frequency of FBARs using varactors and exhibits a large isolation of 76 dB at 2.5 GHz. The FBAR chip (0.25 mm(2)) consists of three identical FBARs connected in wye configuration. FBAR's quality factor (Q) of 1250 and the piezoelectric coupling coefficient k(t)(2) of 3% relax the modulation requirements, achieving nonreciprocity with small modulation to RF ratio better than 1: 800 (3 MHz: 2.5 GHz).

This paper presents a 1.8-mW 2.4-GHz channelized receiver for ISM-band applications. Unlike traditional ISM-band radios which typically require a phase-locked loop (PLL) for channelization, we propose a modified sliding-IF receiver architecture with a suitable local oscillator (LO) frequency plan utilizing a temperature-compensated thin film bulk acoustic-wave resonator (FBAR). This strategy completely eliminates the need for a PLL by directly dividing down the fixed FBAR oscillator frequency. An inductor-less current-reuse balun LNA is proposed allowing a low-power wideband matching as well as noise cancelling. The frequency conversion is achieved by a hybrid mixer, which stacks a switching mixer on a switched-gm mixer for current reuse. It also features good voltage headroom and common-mode noise rejection. The FBAR-based Colpitts oscillator achieves the phase noise of -144 dBc/Hz at 3.5-MHz offset. The measured RX gain, noise figure, and in-band IIP3 are 57.8 dB, 15.7 dB, and -18.5 dBm, respectively, without external crystal and on-chip inductors, which allows us to reduce the size and weight of the receiver system. It dissipates 0.86 mW (RX) and 0.92 mW (LO) from a single 1-V supply.

We present the proposed oscillator architecture to reduce the close-in phase noise as well as power consumption. The proposed Colpitts oscillator removes the current source which is the main source of the 1/f noise conversion. The removal of the current source is compensated by the transformer and cross coupled capacitors. The 2GHz FBAR is used for the high Q frequency selective elements in the oscillator design. According to measurement results, this FBAR based oscillator shows ≥ 10dB reduction in close-in phase noise. In specific, 12dB lower phase noise is achieved at 100Hz offset frequency. Measured power consumption is 350uW, which is almost a half of conventional Colpitts oscillator using same FBAR device [3].

The first fully integrated oven-controlled temperature compensation system with the transformer coupled Colpitts oscillator is developed by 65nm CMOS tech. This work achieves ±1.55ppm frequency stability over the 85°C temperature range which can be used for the GPS application (<;2ppm). An integrated heater in the FBAR chip consumes 14mW power at maximum. The temperature resolution of TDC is 150uK, sufficient to achieve an Allan deviation of 4ppb. This corresponds to a 1.68pJK 2 FOM.

Carrier aggregation increases the requirements on filtering in LTE-A handsets. In particular, aggregation of two or more bands relatively close in frequency range can pose difficult problems. Multiplexers, filter structures sharing a common antenna port and supporting the filtering needs of multiple bands, are a possible answer. Bulk wave filtering in particular has the necessary performance characteristics needed to construct multiplexers. This paper analyzes the increased filtering needs encountered in same-frequency-range down link carrier aggregation, and presents some multiplexer structures that can meet those needs.

A new multi-FBAR structure concept purposely invented and patented for higher power handling capability is presented. In order to reduce self-heating under large RF signal, the thermal resistance and energy flow concepts are approached through a detailed explanation. Finally, the electrical and thermal responses under RF power are described.

We study and compare the pressure sensitivities of different area Rayleigh Lamb wave (RL) mode (S1 mode) and FBAR resonators. The studied RL-mode and FBAR resonators operate at 785MHz and 628MHz respectively. The resonators are fabricated on a released membrane with AlN as the piezoelectric layer. The resonators are hermetically sealed and the manufacturing process uses standard micromachining techniques throughout. The devices exhibit a pressure sensitivity over a range of 15 - 80psi, suitable for Tire Pressure Monitoring Systems (TPMS). The sensitivities of different area resonators are compared.

A low-power sensor interface IC suitable for a differential frequency measurement application is demonstrated. The circuit is used in a FBAR sensor system which includes a sensor and a reference FBAR. The sensor signal is processed and a digital output representing the sensor input is transmitted using a two wire serial interface. The architecture is entirely digital and benefits from scaling to advanced nodes. The IC is implemented in a 130nm CMOS process and consumes 400μW from a 0.75V supply.

Multiple emerging wireless applications (body-worn devices and IoT, for example) will demand previously impossible thin-film form factors and low system cost. One key enabling technology for this paradigm is a new class of radios that offer cost/size approaching RFID while still maintaining peer-to-peer connectivity like more complex radios. These radios need to be cheap and thin, which means they should be fabricated using wafer-scale semiconductor processing. The existing paradigm (quartz crystals used as a frequency reference in radios) is a huge bottleneck in reducing cost and size of these devices. MEMS frequency references have replaced quartz crystals in some applications [1-3]. For example, [1] reports a MEMS reference with 0.5ppm stability but the power consumption (~100mW) and supply voltage (1.8V) are not suitable for low-voltage/low-power radios. [2] reports a 32kHz, 3ppm reference for mobile time-keeping applications, but is unsuitable for radio frequency synthesis due to its low output frequency. In this paper, we report a thin-Film Bulk-Acoustic-Resonator (FBAR) frequency reference suitable for low-voltage/low-power radio applications. The reported FBAR reference achieves a stability of +/- 3ppm from 0 to 90C. We achieve this by using an electronic temperature compensation scheme to improve the intrinsic +/-50ppm stability of an FBAR oscillator down to +/- 3ppm (Fig. 25.9.1). The core of the temperature compensation scheme is a temperature sensor that achieves a 1.75mK resolution at a 100mS sampling time.