The design fabrication and development of a 67.5 kHz capacitive micromachined ultrasonic transducer (CMUT) suited for Martian anemometry is presented in this paper. To have low signal attenuation under Martian conditions, the device operating frequency is limited to 100 kHz. This is due to the low-density carbon dioxide (CO2) atmosphere and acoustic impedance mismatch transduction losses. CMUTs capable of generating frequencies less than 100 kHz need either large Silicon area or higher operating voltages. This is a problem for the battery operation and portability of devices. The devices presented in this paper are designed and fabricated using low cost commercially available surface micromachining technique. COMSOL Multiphysics and MATLAB simulations were used to analyze the device critical design parameters and investigate the operability of devices. Simulation results show that the designed single cell 170- $\mu \text{m}$ radius membrane has a resonant frequency ~65 kHz. The device exhibits a static displacement of 105nm under 20 V DC bias. Using the developed single cell model, a $3\times 10$ array CMUT anemometer was fabricated and evaluated that generates a ~65 kHz acoustic signal in lab environment. This proposed CMUT anemometer can operate for a supply < 38 V. The device performance was evaluated using a commercial air-coupled capacitive microphone named CAP1. Successful transmit-receive of ultrasound from the developed 2D array to CAP1 for separation in the range of 1–15 cm was performed. The experiment results performed in lab environment show the speed of sound and the atmospheric attenuation can be accurately measured using this developed technology with a ±5% accuracy.

The CMUT devices presented in this paper were fabricated using a commercially available MEMSCAPs PolyMUMPs process. The moveable membrane evolves from the available single layer polysilicon. COMSOL simulations were used to model and investigate the effects of a 140 μm and 105 μm radius membranes that are 1.5 μm and 2 μm thick respectively. The results for two different structures designed to operate below 350 kHz are demonstrated in this work. Simulations show that both the devices presented show displacement of over 40 nm. The device snap shut was observed beyond 40 V. This frequency range is suitable to have high SNR and accurate distance measurements. Reducing the size of CMUT devices for the proposed frequency range was a challenge, sorted in this paper. A device capable to generate ultrasound close to 50kHZ is also presented.

This paper proposes gm based CMOS LNA linearization techniques. A common source Cascode LNA with source degeneration is used as a base circuit operating on 0.8 to 2.5 GHz frequency range using TSMC 180nm technology and 1.8V supply. Linearization techniques i)Harmonic Termination, ii) Derivative Superposition, iii) complementary DS and iv) Post distortion are discussed and implemented on casode LNA. Comparison of results shows that IIP3 is improved by 17.8 dBm for Harmonic Termination, 10.7 dBm for Derivative Superposition, 8.5 dBm for Complementary DS and 20.2 dBm for Post Distortion technique.

A highly linear multi-standard low noise amplifier (LNA), is a key block in the design of broadband receivers for wideband wireless communication standards. LNA that achieves high third order intercept point (IIP3) using Derivative Superposition (DS) technique is proposed. The proposed LNA is capable of operating on a frequency range from 0.8GHz to 2.5GHz i.e. Covering most of the high speed data applications as GSM, GPS, UMTS, Bluetooth and Wi-Fi. Linearization technique is applied to a multi-standard Cascode Common Source LNA (CS-LNA). The design is implemented using TSMC 0.18μm CMOS process with 1.3V power supply. Simulation results indicates, the Cascode linearized LNA achieves +21 dBm IIP3, 12.8 dB (min.) to 15.1 dB (max.) gain, 2.75 dB (max.) to 1.63 dB (min.) NF over operating range and stability factor of 2.4 (min.).