Interest in local field potentials (LFPs) and action potential shape has increased markedly. The present work describes distortions of these signals that occur for two reasons. First, the microelectrode recording circuit operates as a voltage divider producing frequency-dependent attenuation and phase shifts when electrode impedance is not negligible relative to amplifier input impedance. Becau...

This paper presents an electronically tunable current/trans-impedance-mode biquad universal filter employing only single multi-output current controlled current conveyor trans-conductance amplifier (MO-CCCCTA) and two grounded capacitors. The proposed filter realizes all the standard filter functions i.e. low pass (LP), band pass (BP) and high pass (HP), notch and all pass (AP) filters in the c...

In this paper the active device for a class E amplifier is modelled as switch in series with a turn on resistance ‘Ron’. Assuming an ideal harmonic load is used the switch equations for the voltage and current waveforms are reviewed and then used to examine how ‘Ron’ affects the efficiency of dc to ac power conversion. This ideal harmonic network is assumed to have optimum input impedance at th...

Design and fabrication of a low cost sensor for measuring electric field over a broad range of electromagnetic (EM) frequency is presented. The electric field probe consists of an electrically short dipole antenna and diode detector connected to an instrumentation amplifier via a high impedance line. The rectified diode voltage is conveyed over the high impedance line for real time data acquisi...

The rapid progress in nanoelectronics showed an urgent need for microwave measurement of impedances extremely different from the 50Ω reference impedance of measurement instruments. In commonly used methods input impedance or admittance of a device under test (DUT) is derived from measured value of its reflection coefficient causing serious accuracy problems for very high and very low impedances...

This study quantifies the dynamic attachment and spreading of porcine pulmonary artery endothelial cells (PPAECs) on optically thin, indium tin oxide (ITO) biosensors using simultaneous differential interference contrast microscopy (DICM) and electrical microimpedance spectroscopy. A lock-in amplifier circuit monitored the impedance of PPAECs cultivated on the transparent ITO bioelectrodes as a...

A highly selective impedance transformation filtering technique suitable for tunable selective RF receivers is proposed in this paper. To achieve blocker rejection comparable to SAW filters, we use a two stage architecture based on a low noise trans-conductance amplifier (LNTA). The filter rejection is captured by a linear periodically varying (LPV) model that includes band limitation by the LN...

The first transistor-based impedance matching circuit for radio-frequency (RF) applications is introduced in this paper. It adapts arbitrary output impedances of RF blocks to desired values between 50 and 250 , from 0 to 5GHz, while occupying only 0.005mm2 of circuit area in a 0.35μm SiGe BiCMOS process. Its superiority over traditional passive-element networks can be resumed by the following f...

Maximizing amplifier PAE and associated output power is critical to preserving the detection capabilities of radar systems. The conflicting criterion for maximizing efficiency is amplifier linearity, which is a well studied tradeoff [1,2]. ACPR shows a measure of linearity by directly quantifying the spectral leakage produced at the amplifier output. Load pull techniques are can be used to meas...

There is a strong interest in the Submillimeter community to increase the IF bandwidth of SIS receivers in order to facilitate extra-galactic astronomy. However, increasing the IF bandwidth generally also means increasing the IF operating frequency of the mixer, because it is very difficult to achieve a good IF impedance match to a low noise amplifier (LNA) for more than an octave bandwidth. Co...