An alternative method for improving current delivery and stability of the conventional LDO regulators are investigated. The Measurement results are compared to a conventional LDO regulator with similar characteristics not enhanced by this technique.
This technique uses the bulk of the pass transistor as a "back-gate" and closes a second loop with a different error amplifier. The second error amplifier, that is connected to the bulk of the pass transistor may have a higher band-width than the first error amplifier (which is connected to the gate of the pass transistor) and hence improves speed and stability of the overall system. More details are available at IEEE website and are accessible by clicking on the micrograph or IEEE TCAS-I link below.

Process: 0.13 µm CMOS
Area: 132x435 µm²
Quiescent Current: 99 µA
Current Delivery Improvement: 78%
PSR: -57 @ 1 MHz
Published in: IEEE TCAS-I

To improve rejection of high frequency ripples as well as speed of load regulations for agile load changes, an ultra-wideband LDO regulator is designed and implemented. This LDO utilizes the reported Compound error amplifier with a different architecture. In the proposed system a novel technique has been proposed to stabilize the system without the use of any off-chip capacitors.

One approach to accurately measure the voltage gain of a high-frequency voltage amplifier which can not derive 50 Ω, is to cascade it with a wideband (or high-band) unity-gain voltage buffer that is capable of driving 50 Ω terminal impedance of RF measurement instruments. On the same note, when it comes to measuring the performance of an integrated VCO, one possible approach can be to use a unity-€“gain buffer as an interface between measurement instruments and the oscillator under the test.
The reported voltage buffer circuits are not satisfying the needs of high frequency RF applications. In this work the high frequency unity-gain voltage buffer presented, is designed by utilizing the previously proposed high unity gain bandwidth LDO voltage regulator. The overall system can provide up to 2 GHz 3 dB bandwidth with 400 mV input voltage amplitude at 2 GHz frequency.

Process: 0.13 µm CMOS
Area: 83x73 µm²
Bandwidth: 2 GHz
Slew rate (V/µs): -185/+254
THD: 34 dB @ 1 MHz
Published in: ICECS

In an alternative approach for high-speed clock and data recovery that is introduced by one of my colleagues Arash Zargaran Yazd , high speed CML comparator arrays are needed to resolve the high speed input data. For that purpose a CML based digital comparator has been designed and laid out. Below is a brief summary of this design.

Process: 90 nm CMOS
Area: 500x500 µm²
Bandwidth: 12.5 Gb/s
Published in: Electronics Letters

In many applications, a DSP unit or microcontroller is utilized to form an ASIC design. This work is showing an approach that can save additional components in such ASIC designs to provide clean supply voltage. This research is using a non-sophisticated microcontroller and one buffer transistor to regulate 2.5V output voltage. The proposed regulator is programmable and studies have been made to ensure its stability under various capacitive and resistive loads. More studies and experimental results are available below.

Regulated Output Voltage: 0.1V - 5 V
Regulation Approach: Successive Approximation
Stability Approach: Adaptive loop delay
Extera Features: Detecting repetitive fluctuations and intelligently suppressing them.
To appear in: ICCE (2015)

Monitoring the blood pressure at the stented site for patients with angioplasty surgery can give critical information which predicts the potential re-narrowing at the operation site.
A tele-monitoring system is designed to work with a capacitive sensor and can operate from minimum harvested energy of 35 nW. Below is a summary of performance for this design.

Process: 0.13 µm CMOS
Area: 3810 µm²
Minimum Operating Voltage: 350 mV
Power Consumption: 35 nW
Sensitivity [kHz/fF]: 3.1@ 0.35 V & 55.0@ 1 V supply voltage
RF Sensitivity: -43.76 dBm
Measurement Setup: In-vitro
Submitted to: T-BIOCAS

This system is a tele-monitoring system with high-resolution in resolving the pressure changes at the monitoring site. The proof of concept design is customized for monitoring the pressure differences between two sides of the implanted stent at the depth of 5 cm inside a patient's body. The antenna that has been used to power up the system is a modified version of the medical stent which is called Antenna Stent. The Antenna stent (aka Stentenna) has dominant inductive characteristics and can establish an inductive coupling with an external inductive reader. That property can increase the power efficiency and the depth of power delivery. More details on this system is available below.

Process: 0.13 µm CMOS
Area: 3810 µm²
Minimum Operating Voltage: 350 mV
Power Consumption: 35 nW
Sensitivity [kHz/fF]: 3.1@ 0.35 V & 55.0@ 1 V supply voltage
RF Sensitivity: -43.76 dBm
Measurement Setup: In-vitro
Preliminary Design Published in: ISCAS
Full Article is Published in: BIOCAS (2014)

In this work, the optimum frequency of operation for transferring power through live tissues are investigated. Moreover, based on calculated maximum power transfer efficiency and the maximum allowable power density that can be exposed to live tissue (govern by FCC), the maximum deliverable power to a typical implantable biomedical device is obtained. To have an accurate simulation, the biomedical implant (in this work the antenna stent) has been precisely modelled, and the electromagnetic properties of different layers of tissues are carefully gathered and fed into two industrially approved EM simulators, namely Ansys HFSS ™ (High Frequency Structural Simulator) and COMSOL Multiphysics ®

Optimum frequency Range: 0.8-1.5 GHz
Maximum Power Transfer Efficiency: -30dB
Maximum Deliverable Power: 56 μW
EM Simulators: Ansys HFSS™ and COMSOL Multiphysics®
Published in: EMBC

In this work, a novel method of sensing the RF current is presented. The proposed technique is fully passive and none-invasive and can be applied into any complex analog and mixed-signal design for fault diagnosis. The current technique requires very little active area and can be adopted in standard CMOS technology.

Process: 0.13 μm CMOS
Maximum Sensing Frequency : 30 GHz
Measured Bandwidth: 8 GHz (limited by measurement instrument's bandwidth)
EM Simulators: ADS Momentum
Sensitivity [V/A]: ~1000@ 5-7 GHz
Published in: Electronics Letters

Backscattering technique is a well-known approach in RFID applications. However, when the passive receiver is an implantable biomedical device buried under live tissues, investigations are required to prove its benefits. Backscattering based transmitters (also known as passive oscillators) are significantly less power hungry than "active" oscillators (e.g., VCOs) and therefore there is a great benefit in using them when the power budget is extremely tight. This work uses an antenna stent as an implantable biomedical device and studies the feasibility of this technique in an in-vitro experiment. You can access to full article (it is open-access to public) by clicking on the figure and links below.

Dimension of the implantable antenna: 20mmx5mm
Maximum Depth of Implant: 50 mm
Measured Backscattered power: -80 dBm @ 50 mm
Measurement setup: In-vitro
Published in: EMBC 2013

I am finishing up an app for iOS, which I called it CheerUP. You can find some screenshots of the app below.

Language: Objective-C
Number of Quotes: +7400
Animation: Objective-C
Platforms: iPhone (4,4S,5,5S,6), iPad (Air)

The current website is written with a word editor {Bracket}. There are three main languages involved in the current website. HTML for content, CSS for format and arrangement and Java. As you may have found out already this website rearranges accordingly as you change the window size. The Java is used to add dynamic features to the html and the content.

Languages: HTML, CSS, Java scripts (js)
Platform: Desktop
Browsers Compatibility: Safari / Chrome
Loading time: 0.8 sec on Intel i7

I am trying to share the best of my knowledge with engineers across the globe. One way to do that is through a Youtube Channel. You can follow the link or search for Kamyar K channel. I am currently hosting more than 20 tutorials on my channel and new tutorials are constantly added(as of Jan'15).

Languages: English
Topics: Ansoft Maxwell & HFSS
Start: November 2014
Update: Avg: 2 tutorials per week