George N. Saddik

Ultra-Wideband Multifunctional Communications/Radar System

We have designed, simulated, fabricated, and tested an ultra-wideband (UWB) multifunctional communication and radar system utilizing a single shared transmitting antenna aperture. Two surface acoustic wave bandpass chirp filters were used to modulate the radar and communications pulses, generating linear frequency modulation waveforms with opposite slope factors. The system operates at a center frequency of 750 MHz with 500 MHz of instantaneous bandwidth. The measured range resolution is 63 cm (25 in) using targets with a radar cross section of 2.7 m2. The probability of detection was measured to be 99%, and the probability of false alarm was 7% with the communication and radar systems operating simultaneously. The bit error rate for simultaneous communication at 1 Mb/s, and radar at 150 kHz pulse repetition frequency and 1.5-ns pulsewidth is 2e - 3. Our UWB multifunctional system demonstrates the ability to simultaneously interrogate the environment and communicate through a shared transmitting antenna aperture, while realizing a simple system architecture with low output power and not employing time-division multiplexing.

dc electric field tunable bulk acoustic wave solidly mounted resonator using SrTiO3

A tunable SrTiO3 solidly mounted bulk acoustic wave resonator has been designed, fabricated, and tested. The solidly mounted resonator was implemented using an acoustical Bragg reflector of alternating high and low acoustic impedance layers. The resonator demonstrated a frequency tunability of 1%, from 5.87to5.81GHz with an applied bias of 0–7.5V, respectively. A return loss of −6.5dB was observed at an applied bias of 7.5V. The quality factor at the resonant frequency was 78 and relatively constant with applied bias. The effective electromechanical coupling coefficient was 2% and near linear with applied bias.

Strontium titanate DC electric field switchable and tunable bulk acoustic wave solidly mounted resonator

A voltage switchable/tunable strontium titanate solidly mounted BAW resonator was implemented using an acoustical Bragg reflector of alternating high and low acoustic impedance layers. In the absence of any bias the device is merely capacitive, but under a DC bias the material becomes piezoelectrically active, leading to a BAW resonance that is effectively turned on and off by the applied field. In the resonant state a voltage-dependent frequency trimming of 1 % is observed, from 7.05 GHz to 6.98 GHz with an applied bias of 0–9 V, respectively. The quality factor at the resonant frequency was approximately 100, limited by the simplicity of the device design. The Q was relatively constant with applied bias, with an effective electromechanical coupling coefficient that varied linearly with applied bias up to a maximum of 3.3 %.

An L-section DC electric field switchable bulk acoustic wave solidly mounted resonator filter based on Ba 0.5S r 0.5 TiO 3

This paper reports on the demonstration of a voltage switchable barium strontium titanate solidly mounted resonator filter at 6 GHz. The filter insertion loss was measured to be −4.26 dB and the return loss to be −13.5 dB. The 3 dB bandwidth was measured to be 72 MHz and the quality factor was calculated to be 83. The data was collected at a dc bias voltage of 10 V.

Improvement of barium strontium titanate solidly mounted resonator quality factor by reduction in electrode surface roughness

Two barium strontium titanate solidly mounted resonators with different bottom electrode surface roughnesses were fabricated and tested. The surface roughness of the bottom electrode was reduced by changing the deposition method of the SiO2 layer in the acoustic Bragg reflector in the solidly mounted resonator. The surface roughness was reduced from 2.81 nm RMS to 1.45 nm RMS. This reduction in the surface roughness contributed to a significant increase in the quality factor of the resonator. The quality factor for the device with a smooth platinum bottom electrode was 110 to 87 over a bias range of 5 to 40 V, and for the device with a rough platinum bottom electrode it was 1 to 31 over the same bias range. The effective electromechanical coupling coefficient was 4% at 40 V and 3.4% at 40 V for the smooth and rough platinum bottom electrodes, respectively.

Temperature dependence of DC voltage activated Ba 0.5 Sr 0.5 TiO 3 solidly mounted resonator

Temperature dependent scattering parameter data was collected on a 30 × 30 µm² voltage activated barium strontium titanate solidly mounted resonator. The frequency variation over the temperature range of −40°C to 120°C normalized to room temperature was as low as 0.41% and as high as 0.84%. The resonant frequency measurements also show a step at −10°C which is believed to be a structural phase transition of the ferroelectric material. The data was collected at a dc bias voltage range of 0V to 30V in 5V increments.

An L-section DC electric field switchable bulk acoustic wave solidly mounted resonator filter based on Ba 0.5 Sr 0.5 TiO 3

This paper reports on the modeling, fabrication, and experimental results of a voltage switchable barium strontium titanate solidly mounted resonator filter at 6 GHz. The filter insertion loss was measured to be -4.26 dB and the return loss to be -13.5 dB. The 3-dB bandwidth was measured to be 72 MHz and the quality factor was calculated to be 83. The data were collected at a dc bias voltage of 10 V. Temperature data were also collected, and the filter demonstrated a 0.71-dB increase in insertion loss and a 7-MHz decrease in center frequency with increase in temperature.

Capacitively coupled dc voltage switchable barium strontium titanate solidly mounted resonator filter

A dc voltage switchable barium strontium titanate solidly mounted bulk acoustic wave capacitively coupled resonators filter has been demonstrated for the first time. The filter consists of two switchable bulk acoustic wave solidly mounted resonators coupled with a high-Q barium strontium titanate capacitor. The resonators have a measured loaded series and parallel quality factors of 135 and 87 in the on-state (30V), respectively. The electromechanical coupling coefficient of the resonators is 6.34 % in the on-state (30V). The insertion loss and return loss of the filter is −3.66 dB and −13.74 dB, respectively.

Towards a High Quality Factor DC Electric Field Switchable Barium Strontium Titanate Solidly Mounted Resonator

Barium strontium titanate solidly mounted resonators (SMR) were fabricated with three different acoustic Bragg reflectors (ABR) on a sapphire substrate. The three devices had ABR structures consisting of W/SiO 2 /W/SiO 2 , Mo/SiO 2 /Mo/SiO 2 , and Pt/SiO 2 /Pt/SiO 2 respectively. The s-parameters of all three devices were measured. The results showed that the quality factor increased as a function of the material in the ABR structure. The quality factor for the devices with tungsten, molybdenum and platinum in the ABR structures are 101, 88, and 31, respectively. This investigation showed how the material in the ABR structure can contribute to the acoustic loss in the device.

Impact of chemical mechanical polishing on the quality factor of Ba 0.5 Sr 0.5 TiO 3 solidly mounted resonator

A voltage activated barium strontium titanate solidly mounted resonator was fabricated and measured. The barium strontium titanate was deposited on a chemical mechanical polished acoustic Bragg reflector with a surface roughness of 0.504nm RMS. Data was collected on the device at a dc bias voltage range of 0V to 25V in 5V increments. The barium strontium titanate solidly mounted resonator showed an effective quality factor of 100 to 180 over the bias range.